Cover sketch: Saw-whet owl, by Bob Hines of the U.S. Fish and Wildlife Service, Washington, D.C.

Habitat, cavity needs, and food sources are outlined for 85 species of birds that nest in holes in dead or dying trees. Removing these trees extensively would severely impact breeding habitats for many of these birds that assist in controlling harmful forest insects. Birds are shown in color; distributions are mapped.

This handbook is the result of a collaborative effort between the Forest Service, U.S. Department of Agriculture, and the Fish and Wildlife Service, U.S. Department of the Interior. Authors Scott and Stone are wildlife research biologists with the Fish and Wildlife Service’s Denver Wildlife Research Center. Scott is based in Fort Collins, Colorado. Authors Evans and Patton are principal wildlife biologists with the Forest Service’s North Central Forest Experiment Station and Rocky Mountain Forest and Range Experiment Station, respectively. Evans is based in Columbia, Missouri, in collaboration with the University of Missouri, while Patton is in Tempe, Arizona, working with Arizona State University.

Special thanks to Arthur Singer, who generously allowed us to use his illustrations from “A Guide to Field Identification: Birds of North America,” by Robbins, Bruun, and Zim, which are reproduced here with permission from the Western Publishing Company. The distribution maps are also reproduced with the permission of Western Publishing Company. © Copyright 1966 by Western Publishing Company, Inc.

We want to thank Kimberly Hardin, Beverly Roedner, Mary Gilbert, Steve Blair, and Michael, Leslie, and Mary Stone for helping us gather literature. A special shoutout to Jill Whelan for her help with literature searches, checking references and scientific names, and putting this publication together. We also acknowledge and greatly appreciate Robert Hamre's support and guidance in preparing this manuscript.

Many species of cavity-nesting birds have declined due to the loss of habitat. In the eastern United States, where ancient forests are gone, purple martins rely almost entirely on man-made nesting structures (Allen and Nice 1952). The hole-nesting population of peregrine falcons vanished with the cutting down of the giant trees they depended on (Hickey and Anderson 1969). The ivory-billed and red-cockaded woodpeckers are currently on the endangered list, mainly because of habitat destruction (Givens 1971, Bent 1939). The wood duck has been very scarce in many parts of its range, at least partly for the same reason, and likely owes its current status to the provision of nest boxes and protection from overhunting.

About 85 species of North American birds (table 1) create nesting holes, use natural cavities from decay, or occupy holes made by other species in dead or decaying trees. These trees, often referred to as snags, have generally been viewed as undesirable by forest and recreation managers because they aren’t visually appealing, clash with other forest management practices, may attract forest insect pests, or could pose fire or safety risks. In the past, dead trees were frequently removed from the forest during timber harvesting. As a result, in some areas, there were very few nesting sites left for cavity-nesting birds. Current well-meaning environmental pressures to focus on harvesting large dead or dying trees, if implemented, would further harm important species like woodpeckers, swallows, wrens, nuthatches, and owls, to name a few.

The majority of cavity-nesting birds eat insects. Since they represent a significant part of the bird population in forests, they play a crucial role in managing forest insect pests (Thomas et al. 1975). Woodpeckers are particularly important predators of several kinds of tree-destroying bark beetles (Massey and Wygant 1973). Bruns (1960) summarized the role of birds in the 2 forests:

Many birds that build nests in cavities are typically resident (non-migrating) species (von Haartman 1968) and are therefore more open to local habitat management practices than migratory species. The availability of nest holes can be a limiting factor for breeding populations of at least some species (von Haartman 1956, Laskey 1940, Troetschler 1976, Kessell 1957). Nest boxes have been well-received by many natural cavity nesters, leading to increased breeding density as a result of providing these structures (Hamerstrom et al. 1973, Strange et al. 1971, Grenquist 1965), which suggests that managing natural snags could be beneficial.

Because nesting needs differ among bird species, forest types, and geographic areas, more research is needed to identify the species, quality, and density of existing and potential cavity trees required to support adequate populations of cavity-nesters. In a study conducted in Montana, for instance, larch and paper birch snags were most commonly used by cavity-nesters (McClelland and Frissell 1975). The most utilized trees were large, broken-topped larches (either dead or alive), greater than 25 inches in diameter at breast height (dbh), and over 50 feet tall. No specific snag density was recommended for managers. In the Pacific Northwest, Thomas et al. (1976) suggested around seven snags per acre to maintain 100 percent of the potential maximum breeding populations of cavity-nesters in ponderosa pine forests, and six per acre in lodgepole pine and subalpine fir. In Arizona ponderosa pine forests, an average of 2.6 snags per acre (mostly ponderosa) were utilized by cavity-nesting birds (Scott, in press[1]). The most frequently used snags were trees that had been dead for six or more years, had more than 18 inches dbh, and had over 40 percent bark cover. While snag height was less critical than diameter, snags taller than 46 feet had more holes than shorter ones. Balda (1975) recommended 2.7 snags per acre to maintain natural bird species diversity and maximum densities in the ponderosa pine forests of Arizona.

Important characteristics related to tree growth that affect nesting cavities include (1) tree size, lifespan, and distribution; (2) regrowth through sprouts, and (3) decay in standing trees (Hansen 1966). While trees measuring less than 14 to 16 inches in diameter at breast height (dbh) when mature are too small to create cavities suitable for wood ducks, they can be significant for smaller species. Trees like aspen, balsam fir, bitternut hickory, ironwood, and others are included in this size range. Short-lived species, such as aspen and balsam fir, typically develop cavities sooner than longer-lived trees. Because sprouting is a major pathway for fungal infections, the vigor of sprouting and the age at which sprouts are formed are crucial factors to consider when managing for hardwood trees that produce cavities. Cavity formation in oaks originating from the base is a slow process, but black oak is a good cavity producer as the trees near maturity; while the heartwood decays quickly, the sapwood remains resistant (Bellrose et al. 1964). Basswood is also a strong cavity producer due to its ability to sprout. Baumgartner (1939), Gysel (1961), Kilham (1971), Erskine, and McLaren (1972), along with others, have provided insights on tree cavity formation for wildlife species. Additional research on how decay from branch scars, cutting, and animal damage affects different tree species is needed to promote effective management of snags.

Removal of snags is also known to reduce some bird populations. For instance, taking out some live trees and snags in an Arizona ponderosa pine forest caused cavity-nesting bird populations to drop by 50 percent (Scott[2]). Violet-green swallows, pygmy nuthatches, and northern three-toed woodpeckers were mostly responsible for this decline. A previously high population of swallows decreased by 90 percent, and a previously low woodpecker population was wiped out. In a nearby area where live trees were cut but snags were left intact, cavity-nesters increased, just as they did in a plot where both live trees and snags remained untouched.

Foresters and recreation managers are now more aware of the aesthetic and economic importance of nongame wildlife, including cavity-nesting birds. In the summer of 1977, the U.S. Forest Service established a national snag policy requiring all Regions and Forests to create guidelines to “provide habitat needed to maintain viable, self-sustaining populations of cavity-nesting and snag-dependent wildlife species.” These guidelines are also intended to include “retention of selected trees, snags, and other flora, to meet future habitat requirements” (USDA Forest Service 1977). 4 Some Forest Service Regions had already implemented policies for snag management. For example, in 1976, the Arizona-New Mexico Region (USDA Forest Service 1976) recommended that three quality snags be retained per acre within 500 feet of forest openings and water, with two per acre in the rest of the forest. The policy also mandates that measures be taken for the continued recruitment of future snags; spike-topped trees with cavities and obvious cull trees should be left for future cavity nesters. Some foresters are now using tags to protect the more suitable snags from fuelwood cutters in high-use areas.

In this book, we've summarized both published data and personal observations on cavity-nesting birds of North America to give land managers a current and convenient source of information about the specific needs of these birds. Bird names follow the American Ornithologists’ Union Checklist of North American Birds (fifth edition, with supplements). Bird illustrations and distribution maps are reproduced with permission from Western Publishing Co. from A Guide to Field Identification of Birds of North America by Robbins et al. (1966). The small range maps show where birds are likely to be found during different seasons. The summer or breeding range is marked in red, winter range in blue; purple indicates areas where the species may be present all year. Red cross-hatching marks areas where migrating birds are likely to be seen only in spring and fall. Length measurements (L) refer to birds in their natural position, while W indicates wingspan.

Percentages of the diet under “Food” in species accounts refer to volume, unless stated otherwise. Since most species' nestlings need insect protein, “Major Foods” mainly relates to adult diets. The appendices include common names of plants and animals mentioned in the text, along with scientific names whenever they were identified.

Habitat: Black-bellied whistling ducks (also known as tree ducks) are commonly found in southern Texas and occasionally in other areas. They prefer open woodlands, groves, or the edges of thickets where ebony, mesquite, retama, huisache, and various types of cacti thrive in freshwater environments (Oberholser 1974, Meanley and Meanley 1958). Their range has expanded due to flooding and the creation of reservoirs.

Nest: Natural spaces in trees like live oaks, ebony, willow, mesquite, and hackberry are preferred, but ground nests and nest boxes are sometimes used. The nest can be located over land or water, but grassy vegetation under “land-bound” nests may be favored over brush (Bolen et al. 1964). A perch near the entrance of the cavity might also influence the choice of nest tree. Both open and closed cavities are utilized. Nest cavities are typically 8.7 feet above ground or water and 23 inches deep, with openings measuring 7.0 × 12.5 inches (Bellrose 1976). Nest boxes should be 11 × 11 × 22 inches high at the front and tapered to 20 inches at the back, with entrances 5 inches in diameter (Bolen 1967). Nest boxes should only be set up if they are predator-proof.

Food: Black-bellied whistling ducks mainly graze (Rylander and Bolen 1974), but they can also dabble and dive for aquatic food. In one study, 92 percent of their diet consisted of plant materials, with sorghum and Bermudagrass being the most common, along with smartweeds, millets, water stargrass, and corn (Bolen and Forsyth 1967). In certain areas, corn and oats play a more significant role in their diet.

Habitat: Wood ducks are found in bottomland hardwood forests where the trees are big enough to create nesting spots and where the water areas supply food and shelter (McGilvrey 1968). These needs can be satisfied in several key types of forests, all of which need to be flooded during the early nesting season: (1) southern flood plain, (2) red maple, (3) central flood plain, (4) temporarily flooded oak-hickory, and (5) northern bottomland hardwoods.

Nest: The ideal natural cavities are located 20 to 50 feet above the ground, with entrance holes measuring 4 inches wide, cavity depths of 2 feet, and cavity bottoms sized at 10 × 10 inches (McGilvrey 1968). It's not advisable to manage for cavities that are more than half a mile away from water, and dead trees, except for cypress, typically don't have usable cavities. Good populations of suitable wood-duck cavities have been noted in various types of timber (Bellrose 1976). Wood ducks readily use nest boxes, and their usage might boost breeding populations, even when natural cavities are plentiful, as long as predators are kept out. The measurements and placement of wood duck boxes are well documented (U.S. Fish and Wildlife Service 1976, Bellrose 1976, McGilvrey 1968).

Food: Wood ducks eat a lot of acorns, typically found in flooded areas. They also enjoy other nuts and juicy fruits, along with leftover corn and wheat (Bellrose 1976). Breeding birds make use of smartweed, buttonbush, bulrush, pondweed, cypress, ash, sweet gum, burweed, and arrow arum seeds. They also consume skunk cabbage, coontail, and duckweed. Duckweed provides a habitat for invertebrates that are part of their diet (Grice and Rogers 1965).

Habitat: The breeding range of the common goldeneye generally coincides with the boreal coniferous forest in North America (Johnsgard 1975, Bellrose 1976). In a Minnesota study, 87 percent of breeding goldeneyes were found on large, sandy-bottomed fish lakes (Johnson 1967), while in New Brunswick, this species preferred areas with marshy shores and nearby old hardwood stands (Carter 1958). In Maine, nests are found in mature hardwoods near lakes with rocky shores, solid bottoms, and clear water. Shallow waters less than 10 feet deep with an irregular shoreline provide shelter for broods and the protective vegetation needed for duckling food (Gibbs 1961).

Nest: Common goldeneyes preferred and had more success in open-top or “bucket” cavities compared to enclosed cavities in New Brunswick (Prince 1968). Most nests were found in silver maples in wetter areas or American elms in drier locations, as well as aspen in northern coniferous forests. The average nest tree was 23 inches in diameter, with cavity dimensions of 8 inches in diameter and 18 inches deep; most entrances were located 6 to 40 feet above the ground (Prince 1968). Wooden nest boxes that measured 12 × 12 × 24 inches with elliptical entrances of 3½ × 4½ inches were widely used in Minnesota (Johnson 1967).

Food: Out of 395 stomachs examined by Cottam (1939), crustaceans (32 percent), insects (28 percent), and mollusks (10 percent) were the main animal foods (totaling 73.9 percent). Crabs, crayfish, amphipods, caddisfly larvae, water boatmen, dragonfly naiads, damselflies, and mayflies were also found. Pondweed, wild celery, and the seeds of pondweed and bulrushes were significant plant materials.

Habitat: Barrow’s goldeneyes reach their highest breeding populations in western North America in moderately alkaline lakes that are small to medium-sized, typically found in parkland areas. They need open water throughout their range, but goldeneyes often prefer areas with dense growth of submerged plants like sago pondweed and widgeon grass. The availability of aquatic invertebrates might be more crucial than nesting sites in determining where they are found (Johnsgard 1975).

Nest: This species doesn’t exclusively nest in trees and has been found using holes in banks or lava beds, rock crevices, ground under shrubs and on islands, haylofts, crows’ nests, and the outer walls of peat shelters for sheep in Iceland (Harris et al. 1954). However, the typical nesting site is in dead stubs or trees like aspen, Douglas-fir, and ponderosa pine within 100 feet of water (Palmer 1976). Abandoned cavities from pileated woodpeckers or common flickers that have been enlarged by natural decay are easily used (Palmer 1976). Cavity entrances range from 3.0 to 3.9 inches in diameter, cavity depths are between 9.8 and 52.9 inches, and cavity diameters range from 6.5 to 9.0 inches (Johnsgard 1975). Nest boxes have been utilized around high lakes in the Cascade Mountains (Bellrose 1976).

Food: The diet of 71 adult Barrow’s goldeneyes was made up of 36 percent insects, 19 percent mollusks, 18 percent crustaceans, 4 percent other animals, and 22 percent plants (Cottom 1939). Naiads of dragonflies and damselflies, caddisfly and midge larvae, blue mussels, amphipods, isopods, and crayfish were key animal foods, while pondweeds and wild celery were the main plant foods.

Habitat: Buffleheads prefer small ponds and lakes in open woodlands (Godfrey 1966). In British Columbia, they mostly nest in the interior Douglas-fir zone, while poplar communities are typically used in Alberta, and ponderosa pine areas are favored in California. There are some scattered breeding records in Oregon, Wyoming, and Idaho, mainly in subalpine lodgepole pine, and in Alaska (Erskine 1971), they nest in Engelmann spruce and cottonwood stands.

Nest: Out of 204 nests observed from California to Alaska, 107 were in aspen trees, 44 in Douglas-fir, 14 in balsam poplar and black cottonwood, 12 in ponderosa pine, 11 in poplar, and 16 in a few other coniferous and deciduous trees (Palmer 1976). Buffleheads prefer natural flicker holes in aspen. They favor dead trees located near (within 220 yards) or in water, and “bucket” or open top cavities are seldom used (Erskine 1971). Forestry practices that leave tree stumps near water while removing most ground litter and debris that could obstruct ducklings from reaching the water are recommended. Nest boxes used by captive buffleheads had entrances 2⅞ inches wide with cavities 7 inches in diameter and 16 inches deep (Johnsgard 1975).

Food: Buffleheads primarily eat animal-based foods. Insects account for 70 percent of their diet during summer in freshwater environments. They also consume midge, mayfly, and caddisfly larvae, along with naiads of dragonflies and damselflies. Water boatmen are the most commonly found and significant food source. Although plant material was present in many stomachs, it mostly consisted of fiber and was likely ingested while they were catching aquatic insects. Pondweed and bulrush seeds were common plant foods. Dragonfly and damselfly larvae are crucial for ducklings' diets in all regions (Erskine 1971).

Habitat: Hooded mergansers prefer wooded, clear water streams, but they also inhabit the wooded shorelines of lakes. The draining of swamps and river bottoms, the removal of snags, and other human activities have harmed this species just like they have harmed wood ducks. Hooded mergansers are more easily disturbed by people and are much more sensitive to declines in water quality compared to wood ducks. Breeding densities often appear to be more related to the abundance and availability of food than to nesting cavities (Johnsgard 1975).

Nest: Cavities at any height can be used in any type of tree; the size and shape of the cavity don't seem to matter (Bent 1923). The natural cavities chosen are similar to those used by wood ducks but with smaller ideal dimensions. There have been reports of frequent use of nest boxes in Missouri, Mississippi, and Oregon (Bellrose 1976). In Oregon, boxes were placed 30 to 50 feet apart in groups of 8 (Morse et al. 1969). Some of the southernmost nesting records for this species come from wood duck nest boxes (Bellrose 1976).

Food: The eating habits of hooded mergansers aren’t well understood, but they seem to be more varied than those of common mergansers. Of 138 stomachs collected from different places in the United States, rough fish accounted for 24.5 percent, game fish and unidentified fish pieces made up 19.4 percent, crayfish 22.3 percent, other crustaceans 10.3 percent, and aquatic and other insects 13.4 percent (Palmer 1976). They sometimes eat large amounts of acorns. They also consume frogs, tadpoles, and mollusks like snails.

Habitat: Common mergansers prefer cool, clear waters in northern boreal or western forests, although they have sometimes nested as far south as North Carolina and Mexico. They often use ponds found in the upper parts of rivers in northern forested areas (Johnsgard 1975). Like hooded mergansers, they need clear water for foraging.

Nest: While hollow trees are the typical nesting sites, it's pretty common to find nests on the ground under dense cover or in rock crevices. They've also been spotted in a variety of other places like chimneys, hawk nests, bridge supports, and old buildings. The type of tree used for nesting and how high up the cavity is doesn’t seem to matter much (Foreman 1976). Nest sites are usually near water (Bellrose 1976) and tend to be reused, likely by the same female (Palmer 1976). Artificial nest boxes have been embraced, especially in Europe. The preferred sizes are 9.1 to 11 inches wide and 33.5 to 39.4 inches high, with entrances measuring 4.7 × 4.7 inches and positioned 19.7 to 23.6 inches above the base of the nest box (Johnsgard 1975).

Food: Efforts to reduce the numbers of this fish-eating merganser have boosted trout and salmon production in several regions, at least for a while. Generally, common mergansers are opportunistic feeders, heavily consuming salmon in some places and suckers, chubs, and eels in others. In warmer areas, their food typically consists of rough fish and forage fish like carp, suckers, gizzard shad, perch, and catfish. In certain locations, aquatic plants, salamanders, insects, or mollusks can also play a significant role in this species' diet (Palmer 1976).

Habitat: Turkey vultures glide over most forest types in the United States and southern Canada, except for the pine and spruce-fir areas in the far northeastern United States. To find food, this common scavenger takes advantage of forest gaps created by roads, powerline corridors, clearcuts, and abandoned fields.

Nest: Preferred nesting sites are often in short supply because of the bird’s large size and the lack of large dead trees. The smell of decaying animals around the nest requires a well-protected location to reduce losses from predators. The nest is usually built at or near ground level (Bent 1937). While nesting sites are often found in hollow trees or logs lying on the ground, these vultures will also nest on cliffs, in caves, and in thick bushes (Gingrich 1914, Townsend 1914). These birds typically return to the same nesting site year after year unless it has been significantly disturbed (Jackson 1903, Kempton 1927).

Food: Turkey vultures are scavengers and eat dead animals, often searching along roads where animals have been hit by cars. They consume snakes, toads, rats, mice, and other available animal remains. It's not uncommon for a dozen or more vultures to gather and feed on a large carcass.

Habitat: The black vulture is located in the southern Great Plains, the southeastern pine forests, oak-hickory forests, and mixed oak-pine forests. It prefers a more southern range than the turkey vulture.

Nest: Similar to turkey vultures, black vultures build their nests in many different conditions. They use the nesting sites as they find them without adding any materials (Hoxie 1886, Bent 1937). Hollow stumps or standing trees are preferred nesting spots when they're available; otherwise, they lay their eggs on the ground, often in thick areas of palmetto, yucca, or tall sawgrass (Bent 1937). Nests have also been found in abandoned buildings.

Food: This scavenger is often seen in towns and cities, feeding on animal waste, leftovers, or trash. Forests are mainly used for roosting and nesting, while feeding typically occurs in more open areas and along highways, where animal carcasses are more common.

Habitat: The peregrine falcon can be found in tundra areas, northern boreal forests, lodgepole pine, and subalpine fir, as well as spruce-fir, southern hardwood-conifer regions, cold desert shrublands, and prairies—primarily in open landscapes and near streams. It's also present around both salt and freshwater marshes (Fyfe 1969, Hickey and Anderson 1969, Nelson 1969). This species is currently listed as “Endangered” in the United States.

Nest: Although the peregrine falcon is now known as a cliff-nester, records show that it used to nest in tree cavities (Goss 1878, Ridgway 1889, Ganier 1932, Bellrose 1938, Spofford 1942, 1943, 1945, 1947, Peterson 1948). The peregrine still utilizes cavities in broken-off trunks in Europe (Hickey 1942), but the hole-nesting population in America seems to have vanished with the cutting down of the large trees they relied on (Hickey and Anderson 1969).

Food: The peregrine falcon mainly hunts birds, from mallards to warblers, usually stunning or killing them while in the air. Mammals and large insects make up only a small part of their diet (Bent 1938). White and Roseneau (1970) discovered fish remains in the stomachs of peregrines in Alaska and suggested that fish might be more common in some peregrine diets than what is usually reported.

Habitat: The merlin is typically found in open areas of boreal forest, including Douglas-fir, Sitka spruce, poplar, aspen, birch, willow, ponderosa pine, Douglas-fir, oak woodlands, and saltwater marshes (Craighead and Craighead 1940, Lawrence 1949, Brown and Weston 1961).

Nest: Similar to the peregrine falcon, most of the merlin's cavity nests were documented before 1910, when they were nesting in poplar, cottonwood, and American linden tree cavities (Bendire 1892, Houseman 1894, Dippie 1895). The merlin typically uses tree nests made by other large birds (like hawks, crows, and magpies) but occasionally nests on the ground under bushes or on cliffs and banks.

Food: Brown and Amadon (1968) discovered that birds accounted for 80 percent (by weight) of the food for merlins, insects for 15 percent, and mammals for 5 percent. Ferguson (1922) examined 298 stomachs and found 4 mammals, 318 birds, and 967 insects. The birds found in the stomachs included small shorebirds, small game birds, and songbirds (which are usually caught in flight). Insect prey included crickets, grasshoppers, dragonflies, beetles, and caterpillars (Bent 1938), while mammals consisted of pocket gophers, squirrels, mice, and bats (Fisher 1893).

Habitat: The American kestrel is the smallest and most common falcon in North America, found in open and semi-open areas across the continent. In the Rocky Mountain region, kestrels are most plentiful on the plains, but they also nest at elevations up to 8,000 feet in Douglas-fir, ponderosa pine, and pinyon-juniper forests (Scott and Patton 1975, Bailey and Niedrach 1965). They have been seen on the highest peaks after the nesting season (Bailey and Niedrach 1965).

Nest: Nest sites can vary widely, but kestrels tend to prefer natural cavities or old woodpecker holes. The following nest sites are listed in order of usage: common flicker holes, natural cavities, cavities in arroyo banks or cliffs, buildings, magpie nests, and man-made nesting boxes (Bailey and Niedrach 1965, Bent 1938, Roest 1957, Forbush and May 1939). Nest boxes, which should be about 10 × 10 × 15 inches, need to be placed 10 to 35 feet above the ground with a 3-inch entrance hole. Natural cavities or nest boxes should be available along the edges of forest openings (Bailey and Niedrach 1965, Hamerstrom et al. 1973, Pearson 1936).

Food: Kestrels hunt from high, open spots where they can see forest clearings, fields, or pastures. Their diet mainly includes insects (especially grasshoppers), small mammals, and sometimes a bird (Bent 1938).

Habitat: The barn owl lives in most types of forests in the United States, except for the higher elevation areas in the Rocky Mountains. They are generally seen as uncommon residents due to their silent, night-time habits, which make them hard for most casual observers to notice. Barn owls also thrive in open country and easily adapt to areas populated by humans (Marti 1974).

Nest: Before humans arrived, barn owls made their nests in natural hollows in trees, cliffs, or canyon walls, but now they also nest in barns, church steeples, birdhouses, mine shafts, and dovecotes (Bailey and Niedrach 1965, Reed 1897).

Food: Barn owls are often found in places where small mammals are abundant; mice, voles, rats, gophers, and ground squirrels make up most of their diet. They rarely hunt birds, except for those that gather in large groups like house sparrows and blackbirds (Marti 1974).

Habitat: This small owl is found in various types of forests below 8,000 feet elevation across the United States. Screech owls prefer trees that are spaced out, along with grassy open areas, for hunting. They particularly like the edges of meadows and fruit orchards in the eastern United States.

Nest: Like other owls, the male screech owl protects a nesting and feeding territory. In the East, it prefers maples, apples, and sycamores with natural cavities or pines with woodpecker holes (Bent 1938). In the plains, it favors natural cavities or flicker holes in cottonwood trees (Bailey and Niedrach 1965). Nest boxes in orchards or residential areas are often utilized. Hamerstrom (1972) suggested a nesting box that measures 8 × 8 × 8 inches with a 3-inch entrance hole.

Food: Screech owls are some of the most nocturnal owls and are rarely seen when they’re feeding. Their main food sources include mice and insects. Fisher (1893) studied 255 screech owl stomachs and discovered that 15 percent contained birds, 36 percent had mice, and 39 percent had insects. Korschgen and Stuart (1972) found mostly small mammals in 419 screech owl pellets from western Missouri. The composition of the screech owl pellets was mainly meadow mice, white-footed mice, and cotton rats.

Habitat: The small whiskered owl is typically found in the dense oak or oak-pine forests of southern Arizona, southwestern New Mexico, and extending into Mexico.

Nest: Nests have been found in both natural cavities and old woodpecker holes in oak, cottonwood, willow, walnut, sycamore, and juniper trees (Bent 1938). Karalus and Eckert (1974) indicate that white oak is one of the preferred nesting sites, and that these small owls tend to nest in cavities in the tree limbs rather than the trunk.

Food: Black crickets, hairy crickets, moths, grasshoppers, large beetle larvae, and centipedes are the main parts of the diet (Jacot 1931). Besides those mentioned by Jacot, Karalus and Eckert (1974) include praying mantises, roaches, cicadas, scorpions, and small mammals as part of the diet.

Habitat: The flammulated owl typically isn’t found in logged areas or in pure conifer stands but needs some understory or a mix of oaks in the forest (Phillips et al. 1964). It lives in forest types like ponderosa pine, spruce-fir, lodgepole pine, aspen, and pinyon-juniper (Grinnell and Miller 1944, Karalus and Eckert 1974).

Nest: Nests are typically found in old flicker or other woodpecker holes, but flammulated owls might use active nests too (Karalus and Eckert 1974). They’ve been seen nesting in pine, oak, and aspen snags (Bent 1938).

Food: The flammulated owl mainly eats insects, but it sometimes catches small mammals and birds. In the few stomachs that have been studied, the identified items included various beetles, moths, grasshoppers, crickets, caterpillars, ants, other insects, spiders, and scorpions (Bent 1938). Kenyon (1947) looked at the stomach contents of one owl and found 4 crane flies, 1 caddisfly, 7 moths, 11 harvestman spiders, and 1 long-horned grasshopper; the bird had apparently choked to death on the grasshopper.

Habitat: The hawk owl lives in many northern forests dominated by poplar, spruce, pine, birch, tamarack, and willow, especially where these forests are interrupted by small prairie burns and bogs (Henderson 1919).

Nest: Hawk owls typically nest in natural cavities or in enlarged holes made by pileated woodpeckers and flickers. Nests have been found in birch, spruce, tamarack, and poplar snags (Henderson 1919, 1925, Bent 1938), and occasionally on cliffs or in crow nests.

Food: This owl hunts a lot during the day and eats small mammals, birds, and insects (Bent 1938). Mendall (1944) looked at 21 hawk owl stomachs; all of them had meadow or red-backed mice in them; two owls had also eaten shrews.

Habitat: The pygmy owl is found in most of the western wooded areas from western Canada to Mexico. It is likely most common in open coniferous or mixed forests and has been specifically reported in ponderosa pine, mixed conifer, and fir-redwood-cedar forests.

Nest: This owl typically makes its nest in old woodpecker holes that vary in size, from those built by hairy woodpeckers to those created by flickers, located 8 to 75 feet above the ground (Bent 1938).

Food: Mice and large insects are likely the most common prey of the pygmy owl, though other small mammals, birds, amphibians, and reptiles have also been noted (Bent 1938). Brock (1958) found a vole, a deer mouse, and a Jerusalem cricket in one owl's stomach and reported seeing another pygmy owl catch a Nuttall’s woodpecker. We saw a pygmy owl in Arizona carrying a small vole. They have also been spotted catching mice in the mountains west of Denver and taking birds near feeders in Boulder, Colorado (Richard Pillmore pers. comm.[6]).

Habitat: This rare small owl lives in the saguaro cactus of Sonoran deserts and in wooded river areas close to the Mexican border.

Nest: Nests are found in old woodpecker holes in mesquite, cottonwood, and saguaro cactus. Nest heights vary from 10 to 40 feet above the ground (Bent 1938, Karalus and Eckert 1974).

Food: The ferruginous owl mainly eats small birds, but it will also occasionally eat insects, small mammals, invertebrates, reptiles, and amphibians (Karalus and Eckert 1974).

Habitat: The elf owl is found only in the southwestern United States, mainly in the saguaro cactus deserts, lowland areas with sycamore and cottonwood trees, and in conifer-hardwood forests at higher elevations.

Nest: One of the most common places for elf owls to nest is in old woodpecker holes in saguaro cacti. They've also been seen nesting in cavities in sycamore, walnut, mesquite, and pine trees (Ligon 1967, Bent 1938, Hayes and James 1963). These cavities are usually found in dead trees or in the dead branches of live trees.

Food: Elf owls mainly eat insects, especially beetles, moths, and crickets. They also consume centipedes and scorpions and have been known to occasionally catch a reptile (Ligon 1967).

Habitat: Barred owls are commonly found in southern swamps and wet river bottoms of the Midwest, and while they are less common, they are still widespread in northern forests. These owls inhabit all types of eastern forests. Although they utilize white pine, these large owls prefer oak forests and mixed hardwood-conifer areas (Nicholls and Warner 1972). Ideal oak forests have dead and dying trees for nesting cavities and lack dense understory, allowing for easy flight and hunting of prey.

Nest: Barred owls prefer natural cavities in hollow trees. If those aren’t available, they sometimes use abandoned nests from crows, raptors, or squirrels (Pearson 1936, Bent 1938). The hollow trees they choose often have hunting perches that offer good vantage points. The recommended size for a nest box is 13 × 15 × 16 inches deep, with an entrance hole that's 8 inches in diameter (Hamerstrom 1972). Nest boxes are more likely to be used if they're located near woods and streams.

Food: Barred owls are nighttime hunters. In western Missouri, over half of their food includes meadow mice, cottontail rabbits, and cotton rats (Korschgen and Stuart 1972).

Habitat: This rare owl is found in most mature conifer forests in the western United States. Forsman (1976) identified 123 pairs in Oregon, with 95 percent living in undisturbed old-growth conifer forests. Karalus and Eckert (1974) characterized the habitat as dense fir forests, heavily wooded cliffs, narrow canyons, and occasionally stream valleys that are well populated with oak, sycamore, willow, cottonwood, and alder.

Nest: Forsman (1976) found spotted owls nesting in the holes of living old-growth conifers, especially Douglas-fir. The nest trees usually had secondary crowns and broken tops due to parasite infections. Cavities were found inside the tops of hollow trunks, between 62 to 180 feet above the ground. Dunn (1901) reported spotted owls nesting in cavities in both live and dead oak and sycamore trees. Spotted owls also nest in cliff cavities and occasionally in abandoned nests of other large birds (Bent 1938).

Food: The main food sources for the spotted owl are mammals and birds, with some occasional insects and amphibians. Forsman (1976) discovered that mammals made up 90 percent of the total biomass consumed; the primary prey species were flying squirrels and wood rats. Marshall (1942) analyzed 23 pellets and the stomach contents of 5 spotted owls and found 6 bats, 4 mice, 31 crickets, 12 flying squirrels, 1 mole, 1 shrew, 4 songbirds, 2 smaller owls, and 1 amphibian.

Habitat: This northern owl is typically found in the mixed conifer-hardwood forests of Canada (Peterson 1961). One juvenile sighting in Colorado during August indicates that this owl might nest in the southern Rocky Mountains (Bailey and Niedrach 1965). Boreal owls are limited to evergreen forests and dense forests of alder, white pine, and spruce.

Nest: Old flicker and pileated woodpecker holes are preferred, usually at a height of 10 to 25 feet (Fisher 1893, Preble 1908, Tufts 1925, Lawrence 1932). Conifer snags seem to be the preferred choice for nest trees, although hardwoods have also been used (Bent 1938).

Food: The main part of the boreal owl’s diet is made up of small rodents. Mendall (1944) looked at the contents of 20 stomachs in Maine and found that 73 percent were mice (mainly meadow voles) and 20 percent were short-tailed shrews. Pigeons and grasshoppers made up the other 7 percent. In Ontario, Catling (1972) found 86.2 percent meadow voles, 5.6 percent deer mice, 4.2 percent star-nosed moles, 2.7 percent masked shrews, and 1.4 percent short-tailed shrews. Small birds, bats, insects, amphibians, and reptiles are also occasionally part of their diet (Karalus and Eckert 1974).

Habitat: Saw-whet owls are small, nighttime hunters of the deep northern forests. They nest in the Rocky Mountains up to about 11,000 feet (Bailey and Niedrach 1965). This widely distributed owl nests in most forest types across the northern half of the United States, but they only rarely nest as far south as central Missouri.

Nest: These small owls prefer to nest in old flicker or other woodpecker holes (Bent 1938). Nesting habitats may be getting better in areas where Dutch Elm disease has affected many elms, and woodpeckers have created nest holes (Hamerstrom 1972). Saw-whets will use nesting boxes if sawdust or straw is provided. Nest boxes should measure 6 × 6 × 9 inches with a 2.5-inch entrance hole (Hamerstrom 1972).

Food: Saw-whet owls mainly eat small mammals and insects. Their diet includes mice, shrews, young squirrels, chipmunks, bats, beetles, grasshoppers, and sometimes small birds (Scott and Patton 1975, Burton 1973, Hamerstrom 1972, Bent 1938).

Habitat: Chimney swifts are found across the eastern half of the United States in both wooded and open areas. They have adapted to human-made structures and are no longer dependent on hollow trees for nesting and roosting.

Nest: Initially, chimney swifts nested in hollow trees, particularly sycamores. They now inhabit chimneys, barn silos, cisterns, and wells (Pearson 1936). Their nests are constructed from twigs, which they stick to a vertical surface with saliva to create a “half-saucer” shape (Forbush and May 1939).

Food: Chimney swifts primarily eat flying insects but will occasionally grab small caterpillars that are hanging from tree branches or leaves (Forbush and May 1939).

Habitat: This small swift is most often found in river valleys surrounded by thick Douglas-fir and redwood forests in the western United States.

Nest: Nests are typically found in tall, hollow tree stumps in burned or logged areas and are constructed from twigs (Peterson 1961, Robbins et al. 1966). Nests have also been observed in unused chimneys and beneath building eaves (Bent 1940).

Food: Flying insects like mosquitoes, gnats, flies, and small beetles caught in mid-air likely constitute the whole diet (Bent 1940).

Habitat: Coppery-tailed trogons are found along riverside streams and in pine-oak forests in Arizona, southwestern New Mexico, and southern Texas.

Nest: Nests are located 12 to 40 feet above the ground in abandoned large woodpecker holes (Bent 1940). Cottonwood and sycamore snags are typically chosen for nesting. Of the 34 species in the Trogonidae family, this is the only one that breeds in the United States (Wetmore 1964).

Food: There's not much information on what these birds eat, but it seems their diet includes both animal and plant matter. Bent (1940) noted the stomach contents of two birds. One had adult and larvae moths and butterflies, while the other had 68 percent insects and 32 percent fruits. The insect diet included grasshoppers, praying mantises, stink bugs, leaf beetles, and larvae from hawk moths, sawflies, and other various insects. The plant-based food included fruits from cissus and red pepper, along with some unidentified plant fiber.

Habitat: Flickers are often spotted around large trees in open woodlands, fields, and meadows across North America. In winter, they sometimes look for shelter in coniferous forests or swamps. Once, there were three recognized species: the yellow-shafted in the East, the red-shafted in the West, and the gilded in the southwestern desert. Now, these are all considered one species.

Nest: Flickers like to nest in open fields or lightly wooded suburban areas where there are plenty of park-like spaces (Bent 1939). Conner et al. (1975) noted that flickers typically nest in edge habitats and, in large forested regions, they only nest in or around clearings. Flickers dig nest holes with a 2.75-inch entrance hole diameter in dead trees or dead limbs from various tree species, including aspen, cottonwood, oak, willow, sycamore, pine, and juniper. Nests can sometimes be as high as 100 feet but are usually between 10 and 30 feet (Scott and Patton 1975, Lawrence 1967).

Food: Sixty percent of the common flicker's diet is animal-based. Out of that, 75 percent consists of ants, more than any other North American bird consumes. Some flickers have been found with over 2,000 ants in their stomachs. The remaining insect material includes beetles, wasps, caterpillars, grubs, and crickets. The plant-based part of their diet consists of weed seeds, cultivated grains, and fruits from wild shrubs and trees (Bent 1939, Forbush and May 1939).

Habitat: Pileated woodpeckers prefer forests with dense timber and secondary growth made up of a mix of deciduous and coniferous trees for their year-round habitat. These large woodpeckers have become less common across much of their former range due to extensive agriculture and logging that have removed large areas of old growth forests. In the Ozarks, they thrive wherever there are still significant forests, especially in places where early 1900s logging practices have left behind scattered large cull trees.

Nest: Pileated woodpecker nests have been found in beech, poplar, tulip-poplar, birch, oak, hickory, maple, hemlock, pine, ash, elm, basswood, and aspen trees. The heights of the cavities range from 15 to 70 feet, with an entrance hole that can be up to 4 inches in diameter (Hoyt 1941, 1957). They prefer tall dead trees with smooth surfaces and few branches. A tree may be used for several years, but it's rare for a nest hole to be reused. This behavior creates cavities for other wildlife, including wood ducks, owls, and squirrels (Hoyt 1957). Timber stands with sawtimber of 15 to 18 inches dbh provide adequate habitat as long as there is a supply of dead and decaying trees (Conner et al. 1975).

Food: Insects make up over 70 percent of the diet of pileated woodpeckers. Ants (especially carpenter ants) and beetles are the main food sources. In the fall, dogwood berries, wild cherries, acorns, and other wild fruits are part of their diet (Bent 1939).

Habitat: Red-bellied woodpeckers are commonly found in southeastern forests. This bird has behaviors similar to those of the red-headed woodpecker, but the red-headed prefers open woodlands, farmyards, and field edges, while the red-bellied prefers larger forested areas. Bailey and Niedrach (1965) reported that the red-bellied woodpecker is expanding its range westward along the river valleys of the Great Plains.

Nest: These woodpeckers typically dig nest holes in dead branches of living trees. They have been found excavating in many different tree species, at heights ranging from 33 to 72 feet above the ground (Reller 1972). The cavities are usually located in mature forests. From September to January, males and females sleep in separate holes. Often, one of the roost holes (usually the female's) becomes the nest site (Kilham 1958).

Food: While red-bellied woodpeckers mainly eat insects, they actually consume more plant material than most woodpeckers. They eat insects like ants, adult and larval beetles, and caterpillars. Their plant diet includes grains, berries, and the fruits of holly, dogwood, and poison ivy. In the fall, they store acorns and berries in crevices (Kilham 1963, Bent 1939).

Habitat: The golden-fronted woodpecker prefers living in mesquite and river woodlands in Texas and Oklahoma. Cooke (1888) noted that this species was commonly found in the lower Rio Grande Valley, Texas, in 1884.

Nest: The nesting behavior of the golden-fronted woodpecker is similar to that of the red-bellied woodpecker (Pearson 1936). They mainly use tall pecan, oak, and mesquite trees for nesting (Bent 1939). Sometimes, they also nest in fence posts, telephone poles, and bird boxes (Reed 1965).

Food: The diet of the golden-fronted woodpecker includes both insects and plant material. Grasshoppers account for more than half of the animal matter, while other insects consist of beetles and ants (Pearson 1936, Bent 1939). The plant material they eat includes corn, acorns, wild fruits, and berries (Bent 1939).

Habitat: This woodpecker is found on desert mesas alongside creosote bushes, mesquite, and saguaro cacti from central Arizona to the borders of nearby states. It's also commonly seen in river valleys and foothill canyons among cottonwoods, willows, and sycamores.

Nest: The Gila woodpecker makes holes in saguaro cacti for its nests. It also uses cottonwoods, willows, and mesquites at higher elevations (Bent 1939, Ligon 1961).

Food: The diet of the Gila woodpecker includes ants, beetles, grasshoppers, fruits from the saguaro cactus, and mistletoe berries (Bent 1939). This woodpecker has been known to take eggs from the nests of different songbirds.

Habitat: Red-headed woodpeckers like to nest and roost in open spaces. They prefer farmyards, edges of fields, and timber areas that have been treated with herbicides or burned. Redheads are attracted to places with lots of dead trees and rich, green ground cover, but they don’t like dense forests with closed canopies. They can be found all across the East and along wooded streams from the prairie to eastern Colorado and Wyoming. There is often tough competition for nesting spots where starlings are common (Bailey and Niedrach 1965).

Nest: Red-headed woodpeckers usually carve out holes in the trunks of dead trees. These holes are made 24 to 65 feet above the ground, and the 1.8-inch wide entrance hole often faces south or west (Reller 1972). These woodpeckers might create new holes each year or use old nesting sites.

Food: Red-headed woodpeckers eat roughly half animal matter (mainly insects) and half plant matter. Occasionally, they destroy the eggs or young of other birds. While they consume a wide range of plant materials, acorns from pin oak make up a significant part of their winter diet. They store nuts whole or in pieces in cracks and crevices in bark, and in cavities that are sealed with bits of bark when full. These birds also store insects (especially grasshoppers) along with acorns in cavities and crevices (Kilham 1963, Bent 1939).

Habitat: The acorn woodpecker is a common resident of mixed oak-pine forests and nearby open grasslands from Oregon along the Pacific Coast to the southwestern United States.

Nest: Acorn woodpeckers build communal nests, where the entire group helps feed the young (Wetmore 1964). They typically dig holes in ponderosa pine, but they also use live and dead oaks of different species, sycamore, cottonwood, and willow for nesting. Their old holes are crucial for secondary cavity nesters like small owls, purple martins, violet-green swallows, nuthatches, house wrens, and kestrels (Bent 1939).

Food: As the name suggests, acorn woodpeckers mainly eat acorns that they stash in holes drilled into communal trees. They also consume sap from various oak species from midwinter to summer (MacRoberts and MacRoberts 1972). Around 25 percent of their diet consists of insects, including grasshoppers, ants, beetles, and flies (Bent 1939). They eat almonds, walnuts, and pecans when those nuts are available.

Habitat: Open or park-like ponderosa pine forests are likely the main breeding habitats for the Lewis’ woodpecker. These woodpeckers also nest in areas that have been burned, such as Douglas-fir stands, mixed conifer forests, pinyon-juniper regions, riparian areas, and oak woodlands (Bock 1970).

Nest: The Lewis' woodpecker usually digs out its own nest cavity, but it will also use natural cavities or holes made in previous years. Bock (1970) summed up the following nest data: height range from 5 to 170 feet; 47 nests in dead stubs and 17 in live trees; 29 nests in conifers, 31 in cottonwood and sycamore, 6 in oaks, 2 in power poles, 1 in juniper, and 1 in catalpa. At Boca Reservoir, California, 10 out of 11 nests were in dead ponderosa pines, and the other was in a hollow part of a living pine.

Food: Insects like flies, ladybug larvae, tent caterpillars, ants, and mayflies were the main food source for Lewis’ woodpeckers during spring and summer (Bock 1970). Fruits and berries were the most commonly consumed food in late summer and fall, while in winter, they mostly relied on acorns and almonds that they collected and stored in crevices of dead trees, utility poles, and oak bark. Hadow (1973) noted that on snowy days when insects were inactive, Lewis’ woodpeckers in southeastern Colorado spent 99 percent of their feeding time eating from their supplies of acorns and corn kernels.

Habitat: The yellow-bellied sapsucker (sometimes called the red-naped) is most common near streams in mixed hardwood-conifer forests. It can also be found in ponderosa pine, aspen, mixed conifer, lodgepole pine, and in mixed stands of fir-larch-pine.

Nest: Yellow-bellied sapsuckers usually nest in holes in dead or live trees with decayed wood. Aspen seems to be their favorite (Howell 1952, Lawrence 1967, Kilham 1971), but nests have also been found in ponderosa pine, birch, elm, butternut, cottonwood, alder, willow, beech, maple, and fir (Bent 1939). Kilham (1971) observed that nest trees were often infected by the Fomes fungus. Nest height ranges from 5 to 70 feet off the ground. The same nest tree is often reused, but a new cavity is dug out each year.

Food: The yellow-bellied sapsucker eats sap year-round, but the quantity and types of trees they use change with the seasons (Tate 1973, Lawrence 1967). These birds typically tap one or two “favorite trees” in their territory; Oliver (1970) discovered that these are usually trees that have been damaged (by logging, porcupines, etc.). About 80 percent of their insect diet consists of ants (McAtee 1911). They also eat other insects like beetles and wasps, but they don't consume woodboring larvae. The small amount of plant matter they eat includes fruits from dogwood, black alder, Virginia creeper, and blackberries (Bent 1939).

Habitat: This sapsucker likes mixed conifer-hardwood forests in the Rocky Mountain area but also lives in the subalpine spruce-fir-lodgepole zone, as well as ponderosa pine, Douglas-fir, and aspen forests.

Nest: The choice of tree species for nesting seems to vary between regions. Bent (1939), Packard (1945), Bailey and Niedrach (1965), Burleigh (1972), and Jackman (1975) reported that Williamson’s sapsuckers primarily nest in conifers. Other authors (Rasmussen 1941, Hubbard 1965, Tatschl 1967, Ligon 1961, Crockett and Hadow 1975) observed a preference for aspens. Of the 57 nests examined in Colorado by Crockett and Hadow (1975), 49 were in aspens, particularly aspens infected by the Fomes fungus; when pines were used, there were no suitable aspen sites nearby. In Arizona, we found 17 nests in aspen snags, 3 in aspens with dead tops, and 1 nest in a live aspen.

Food: Williamson’s sapsuckers eat about 87 percent animal and 13 percent plant material (Bent 1939). Most of their animal diet consists of ants, while their plant diet mainly includes cambium. Similar to the yellow-bellied sapsucker, the Williamson’s sapsucker feeds on sap, particularly in the spring, and chooses “favorite trees” that it taps regularly (Oliver 1970).

Habitat: Hairy woodpeckers live in almost all types of forests from central Canada downwards.

Nest: Live trees in open woodlands are the preferred nesting spots for hairy woodpeckers. This species creates a nest entrance that perfectly fits its head and body size (1.6 to 1.8 inches). Since this size is also appealing to starlings and flying squirrels, hairy woodpeckers frequently deal with invasions (Kilham 1968a, Lawrence 1967). Hairy woodpeckers will often excavate the entrance to camouflage or hide it, such as on the underside of a limb. Nest heights range from 15 to 45 feet, but they are usually around 35 feet high. Hairy woodpeckers often reuse the same hole year after year.

Food: Hairy woodpeckers like to feed on insects found in dead and sick trees (Bent 1939). About 80 percent of their diet consists of animal matter, with adult and larval beetles, ants, and caterpillars being the most commonly eaten. Their mostly insect diet is also supplemented with fruits, corn, acorns, hazelnuts, and various other foods (Beal 1911, Bent 1939). Males search in trees away from the nest for large insects (usually borers) found deep within the wood. Females forage near the nest, looking for small prey on the surface of trees, shrubs, or on the ground (Kilham 1968a).

Habitat: Downy woodpeckers live in most wooded areas of North America. They are missing or rare in dry deserts and not common in heavily forested regions. Their preferred habitats include open woodlands, hammocks, orchards, roadside hedges, farmyards, and urban areas (Bent 1939). Occasionally, these birds nest at elevations above 9,000 feet in the central Rockies (Bailey and Niedrach 1965). Most populations are considered nonmigratory; however, there is some movement from north to south and from high elevations to the plains during winter.

Nest: Downy woodpeckers are similar to common flickers in many of their nesting behaviors. Both tend to carve out their nests near the tops of dead trees in relatively open forest areas. They usually create new cavities each year in the same tree, but they typically don't use other birds' cavities or reuse old ones (Lawrence 1967). In the fall, these birds dig fresh holes to serve as winter roosts (Kilham 1962). Nest holes are usually located 8 to 50 feet above the ground, with an entrance hole measuring 1.2 to 1.4 inches in diameter (Bent 1939).

Food: The diet is around 75 percent animal and 25 percent plant material. The animal portion mainly consists of economically harmful insects. Kilham (1970) found that beetles, primarily wood-boring larvae, accounted for 21.5 percent of the diet. Other components included ants (21 percent), caterpillars (16.5 percent), weevils (3 percent), and fruit (6 percent). Like hairy woodpeckers, downy woodpeckers have been recognized for helping to reduce forest pests (MacLellan 1958, 1959, Olson 1953).

Habitat: Ladder-backed woodpeckers are usually seen in mesquite and deciduous woodlands near streams in the desert areas of the Southwest.

Nest: Ladder-backed woodpecker nests can be found in different types of trees, including mesquite, screw bean, palo verde, hackberry, china tree, willow, cottonwood, walnut, and oak, typically between 2 to 30 feet off the ground. They sometimes also use saguaro cactus, yucca stalks, and branches for nesting, along with telephone poles and fence posts (Bent 1939, Phillips et al. 1964).

Food: Insects, particularly larvae from wood-boring beetles, caterpillars, and ants, are important food sources. The ladder-backed woodpecker has also been noted to eat the ripe fruit of the saguaro cactus (Bent 1939).

Habitat: This western woodpecker lives in oak woodlands, riverbanks, and chaparral areas west of the Sierras in California.

Nest: Based on a literature review and personal observations, Miller and Bock (1972) summarized the following nest-tree data for 57 nests: 23 percent were in oak, 19 percent in willow, 18 percent in sycamore, 16 percent in cottonwood, and 12 percent in alder. Cavities were dug into dead limbs and trunks of trees, ranging from 3 to 45 feet above the ground.

Food: About 80 percent of Nuttall’s woodpecker's diet consists of insects, including 28 percent beetles, 15 percent true bugs, 14 percent caterpillars, and 8 percent ants (Beal 1911). Most of the insects are picked off trunk and branch surfaces or caught in mid-air (Short 1971). Wild fruits, poison oak seeds, and occasional acorns make up the plant-based part of the diet. Nuttall’s woodpeckers in California have been seen eating almonds, sometimes stealing from the caches of Lewis’ woodpeckers (Emlen 1937, Bock 1970).

Habitat: Arizona woodpeckers live in live oak and oak-pine forests and canyons at elevations between 4,000 and 7,500 feet in Arizona and New Mexico.

Nest: The Arizona woodpecker drills holes in dead branches of living trees, mainly walnuts, oaks, maples, and sycamores. One nest was found in a mescal stalk (Bent 1939).

Food: This woodpecker likely mainly eats adult and larval insects, along with some fruit and acorns, but not many details about its food sources have been shared (Bent 1939).

Habitat: Red-cockaded woodpeckers require open, mature pine forests that are at least 60 years old and have a high frequency of fires (Bent 1939, Jackson 1971, Hopkins and Lynn 1971). The pine species they use during the breeding season include longleaf (Crosby 1971), slash (Lowry 1960), loblolly (Sprunt and Chamberlain 1949), and shortleaf (Sutton 1967). Red-cockaded woodpeckers are listed as an “Endangered species” at the national level.

Nest: These woodpeckers prefer nesting in living pines that are infected with red heart rot. These trees have a soft, easily excavated interior while still maintaining a living exterior, making them less likely to catch fire compared to dead trees. Cavities can often be reused for at least 20 years and may be used for several years by the same pair (Ligon 1971). The height of the cavity is influenced by the location of the red heart infection as well as the height and density of the undergrowth (Crosby 1971). Most cavities face west, and when they are found in leaning trees, they are usually on the lower side (Beckett 1971, Baker 1971).

Food: Insects make up the majority of the diet of red-cockaded woodpeckers. Beal (1911) and Beal et al. (1916) studied 99 stomachs and found 86 percent insects and 14 percent plant matter, mostly mast. Beetle larvae (16 percent) and ants are important parts of their year-round diet. The corn earworm can be a major food source for several weeks when conditions are right (Ward 1930). The recorded plant materials they eat include wax myrtle, magnolia, poison ivy, wild grape, pokeberry, blueberry, wild cherry, black gum, and pecan (Beal 1911, Baker 1971, Ligon 1971).

Habitat: The main habitat of the white-headed woodpecker is open ponderosa pine forests stretching from Washington to central California. It can also be found in sugar pine, Jeffrey pine, and red and white fir forests (Grinnell and Miller 1944).

Nest: This woodpecker appears to favor dead pines, but nests have also been discovered in live and dead fir, oak, and aspen. White-headed woodpeckers typically dig a new nest cavity each year and often create several holes before choosing one to use for nesting (Bent 1939). The average height of a nest is 8 feet above the ground.

Food: White-headed woodpeckers mainly eat pine seeds in the winter and early spring, and insects in the summer. Tevis (1953) found that 60 percent of their annual diet consists of pine seeds, while 40 percent is made up of insects. Ants accounted for half of their insect diet; other insects they consumed included woodboring beetles, spiders, and fly larvae (Beal 1911, Grinnell and Storer 1924, Ligon 1973).

Habitat: The conifer forests in the north are preferred, but this three-toed woodpecker is not common even in its favorite habitat. The types of forests include mixed conifer, lodgepole pine, white fir, subalpine fir, tamarack swamps, boreal spruce-balsam fir, Douglas-fir, and mixed hardwood-conifer.

Nest: This species typically digs its nests in dead trees or live trees that have decayed centers, particularly in places that have been burned or logged (Bent 1939). Nests are usually found in spruce, balsam fir, pines, or Douglas-fir, but maple, birch, and cedar have also been utilized.

Food: This species has a diet similar to that of the northern three-toed woodpecker. Beal (1911) found that 75 percent of its food consists of woodboring beetle larvae, primarily long-horned beetles and metallic woodboring beetles. They also eat weevils and other beetles, spiders, and ants, along with some wild fruit, nuts, and cambium. Beal estimated that each three-toed woodpecker consumes about 13,675 woodboring beetle larvae each year.

Habitat: This extremely helpful woodpecker is typically found in the coniferous forests of the West, although it can also be spotted from time to time in the Northeast.

Nest: The northern three-toed woodpecker digs out nest cavities each year in standing dead trees or in the dead branches of live trees with decayed heartwood (Jackman and Scott 1975). Their nest cavities have been found in pine, aspen, spruce, and cedar trees (Bent 1939). In Arizona, we discovered two nests in ponderosa pine snags.

Food: The northern three-toed woodpecker is likely one of the most crucial birds in controlling forest insect pests in the western United States. Massey and Wygant (1973) found that spruce beetles made up 65 percent of their diet in Colorado. During the winter, when other foods were scarce, spruce beetles accounted for 99 percent of their food intake. West and Speiers (1959) reported that both species of three-toed woodpeckers in the northeastern United States feed on elm bark beetles, which spread Dutch elm disease. Koplin (1972) estimated that 20 percent of a native spruce beetle population and 84 percent of an epidemic population in Colorado were eaten by three species of woodpeckers, with the northern three-toed being the most significant. Other foods include ants, woodboring and lepidopteran larvae, fruits, nuts, and cambium (Beal 1911, Massey and Wygant 1973).

Habitat: Cooke (1888) and Bent (1939) described the largest woodpecker in North America as rare, shy, and only found in dense timber in unspoiled cypress swamps and lowland forests of the South. Tanner (1942) noted that the ivory-billed woodpecker thrives in heavily forested areas that are often flooded alluvial land beside rivers, consisting of oaks, cypress, and green ash. The most recent sightings (between 5 and 10 pairs) have been reported in lowland hardwoods that have been logged but still feature some large, mature trees (Dennis 1967). They are listed as an “Endangered species” nationally.

Nest: Nest cavities of this species have been observed in nearly every type of tree found within the ivory-bill's habitat (Greenway 1958). The square-shaped holes (Dennis 1967) are located high, between 16 to 65 feet up, in the trunks of both living and dead trees (Greenway 1958, Forbush and May 1939).

Food: Ivory-billed woodpeckers could be economically significant if it weren't for their small population (Greenway 1958). The woodboring larvae that make up about a third of their diet (Beal 1911) are harmful to trees (Pearson 1936) and are most plentiful in areas with many recently dead and dying trees due to flooding, fires, insect infestations, or storms. The birds remain in these areas as long as there are plenty of larvae available (Dennis 1967). They also consume the fruit from magnolia and pecan trees (Beal 1911).

Habitat: The sulphur-bellied flycatcher is commonly found in riparian areas with sycamore trees in deep canyons at elevations between 5,000 and 7,500 feet in the Huachuca Mountains of Arizona.

Nest: Typically, the nest of this species, made from leaf stems (Peterson 1961), is built in a natural cavity in a large sycamore tree at a height between 20 and 50 feet off the ground. The cavity is usually a knothole where a large branch has snapped off (Bent 1942). At least one member of each pair may return to the same nesting site every year.

Food: There's little information available about the eating habits of this flycatcher, but it's clear that insects caught in the air are the main part of its diet. It seems that small fruits and berries are also consumed (Bent 1942).

Habitat: Great crested flycatchers are commonly found in deciduous and mixed woods east of the Rockies. They used to be a deep forest bird, but with more clearing and thinning of forests, there are now fewer cavities available. They appear to be adapting well to less densely wooded areas, places treated with herbicides, and the edges of forests and fields (Hespenheide 1971, Bent 1942).

Nest: Great crested flycatchers use natural holes or digs made by other animals. Nests can be found in different types of trees, anywhere from 3 to 70 feet off the ground (mostly under 20 feet). They make a bulky nest and prefer deep cavities. Before starting to build a nest, they usually fill a deep cavity with debris up to 12 to 18 inches from the top. They are recognized for their tendency to include a snake skin in the nest or hanging it from the opening of the cavity (Bent 1942).

Food: Studies on food habits have revealed that great crested flycatchers consume 94 percent animal matter and 6 percent plant matter. They mostly feed on butterflies, beetles, grasshoppers, crickets, katydids, bees, and sawflies. The plant matter primarily consists of wild fruits. Most of their food is caught in flight, just like typical flycatchers (Bent 1942).

Habitat: The Wied’s crested flycatcher prefers to live in desert saguaros, deciduous woodlands, and riparian vegetation in the Southwest.

Nest: Nests made from sticks, weeds, and trash are built in abandoned woodpecker holes in saguaro cacti at heights ranging from 5 to 20 feet above the ground. Sometimes, sycamores, cottonwoods, and fence posts are used (Bent 1942).

Food: This species' diet is similar to that of other crested flycatchers, mainly made up of beetles, flying insects, and possibly some berries and fruits (Bent 1942).

Habitat: The ash-throated flycatcher lives in thick mesquite bushes, oak forests, saguaro cacti, riverbank vegetation, and pinyon-juniper woodlands. Its range extends from Washington to the southwestern United States and Texas.

Nest: The ash-throated flycatcher isn’t very picky about which trees it uses as long as there’s a cavity. It has been known to use woodpecker holes, exposed pipes, and nest boxes. Common nest trees include mesquite, ash, oak, sycamore, juniper, and cottonwood (Bent 1942).

Food: This species primarily eats animal matter. Beetles, bees, wasps, bugs, flies, caterpillars, moths, grasshoppers, spiders, and other insects make up about 92 percent of its diet. Mistletoe, berries, and other soft fruits make up the rest (Bent 1942).

Habitat: Olivaceous flycatchers are found in thick oak bushes, pinyon-juniper forests, and along canyon streams in Arizona and southwestern New Mexico.

Nest: Nests are found in natural openings or old woodpecker holes. Oak trees are the favored choice, but nests have also been seen in ash and sycamore trees (Bent 1942).

Food: Limited evidence on the eating habits of this species suggests that its main food items are small insects, including grasshoppers, termites, mayflies, treehoppers, various bugs, moths, bees, wasps, and spiders (Bent 1942).

Habitat: The western flycatcher prefers moist deciduous or coniferous forests and areas near flowing water with tall trees (Grinnell and Miller 1944).

Nest: Western flycatchers sometimes build their nests in cavities, but they use a variety of nesting sites. Davis et al. (1963) found four nests in natural cavities in willows and oaks, and six behind strips of bark in sycamores and willows. Nests are often reported in natural rock crevices, on tree branches and forks, and on ledges of buildings (Bent 1942, Davis et al. 1963, Beaver 1967).

Food: Nearly all of what the western flycatcher eats consists of insects caught in mid-air. A study of 23 stomachs revealed that 31 percent contained flies, 25 percent had beetles, 23 percent included lepidopterans (which consists of pupae and adults of spruce budworms), and 17 percent contained hymenopterans (Beaver 1967).

Habitat: Ponderosa pine provides the preferred habitat for violet-green swallows (Bailey and Niedrach 1965), but they can also be found in aspen-willow and spruce-aspen forests. They like open or fragmented woods or the edges of thick forests.

Nest: Violet-green swallows build their nests in holes, cavities, and crevices in various places. When these birds are plentiful, the need for nesting spots can often exceed the available options, so they may use almost any accessible cavity. Observations have noted that these swallows utilize old nests made by cliff swallows and even burrows of bank swallows (Bent 1942). Winternitz (1973) reported that violet-greens used old woodpecker holes in living aspen trees for nesting, but in Arizona, we mostly found them nesting in old woodpecker holes in ponderosa pine snags. We discovered one in the dead top of an aspen, five in dead tops of ponderosa pine, and 26 in ponderosa pine snags. Nest heights varied from 16 to 80 feet, with an average height of 43 feet.

Food: This species' diet consists entirely of insects caught in flight. It includes leafhoppers, leaf bugs, flies, flying ants, and some wasps, bees, and beetles (Bent 1942). In Colorado, Baldwin (pers. comm.[7]) discovered that insects made up 99 percent of the stomach contents of six violet-green swallows. Flies were the most commonly found insect. Scolytid beetles, seed and leaf bugs, various insects, and a few spiders were also identified.

Habitat: Tree swallows breed across North America from the northern part of the United States up to the edge of tree growth. They migrate through the Central and Southern states and mainly winter in Central America.

Nest: Tree swallows like to nest in natural cavities and old woodpecker holes—typically close to water. The shortage of natural cavities, competition for available ones, and the presence of nest boxes have led to a change in nesting habits towards using nest boxes in the eastern United States (Bent 1942, Low 1933, Whittle 1926). They often use bluebird boxes and purple martin houses. Although tree swallows are not colonial, they will nest within 7 feet of each other if there are enough meadows, marshes, or water areas for feeding (Whittle 1926). In the West, woodpecker holes in aspen, spruce, and pine are the most common nesting sites (Bailey and Niedrach 1965).

Food: This species is the first of the swallows to arrive in the north in spring and the last to leave in the fall. Since tree swallows can survive on seeds and berries, they aren't as reliant on insects as other swallows. They particularly like waxmyrtle and bayberry when these are available. The proportions of plant food in their diet are 1 percent in spring, 21 percent in summer, 29 percent in fall, and 30 percent in winter (Martin et al. 1951, Forbush and May 1939).

Habitat: The natural nesting population of purple martins prefers open woodlands or cleared forests where there are suitable dead trees. Purple martins have been seen in oak, sycamore, ponderosa pine, Monterey pine, spruce, and fir forests throughout California (Grinnell and Miller 1944). In the Southwest, the purple martin breeds in the ponderosa pine areas and the saguaro cactus desert.

Nest: The western purple martin hasn’t adapted to nesting in boxes as well as the eastern version (Bunch 1964), and a lot of the western population relies on holes created by woodpeckers, typically in tall pines in fairly open forest areas (Bent 1942). Martins also nest in old woodpecker holes in saguaro cactus. We’ve recorded 21 nests near Cibecue, Arizona, all in ponderosa pine snags. The nests were located 25 to 35 feet above the ground. Nest compartments in martin houses should be 6 × 6 × 6 inches, with an entrance hole that’s 2½ inches in diameter, positioned 1 inch above the floor. The boxes should be set up 15 to 20 feet off the ground.

Food: The purple martin feeds while flying, mainly on insects, but occasionally eats some spiders (Beal 1918). Johnston (1967) looked at the stomach contents of 34 martins collected in April, May, June, and August in Kansas. The main food items included beetles, true bugs, flies, bees, and wasps. Although the purple martin is recognized for eating a lot of mosquitoes (Bent 1942), this was not documented in the two studies on their eating habits mentioned.

Habitat: Black-capped chickadees nest across southern Canada and the northern half of the U.S. In Missouri, black-capped chickadees typically nest north of the Missouri River, while Carolina chickadees are found south of the River. Their breeding range goes further south at higher elevations in the Rocky and Appalachian Mountains compared to lower areas. In Colorado, black-caps are most common in ponderosa pine and aspen forests (Bailey and Niedrach 1965).

Nest: Chickadees nest in cavities but will roost anywhere convenient, typically not in cavities (Odum 1942). The best nesting sites are stubs with partially rotted cores and solid shells. They usually dig their own cavities but will also use natural cavities or nest boxes. Black-capped chickadees may occasionally nest in a cavity they used the previous year after making some changes. Their preferred nesting sites in eastern forests are tree species that occur in the early growth stages but are short-lived and remain as decaying stubs in the intermediate stages (Odum 1941, Brewer 1961).

Food: The diet of the black-capped chickadee consists of 70 percent animal matter and 30 percent plant matter. The majority of the plant matter comes from mast, mainly from coniferous trees, along with fruits like bayberry, blackberry, blueberry, and poison ivy. The animal food they consume (mostly insects) includes caterpillars, eggs, moths, spiders, and beetles. In winter, their diet mainly includes larvae, eggs, katydids, and spiders (Bent 1946, Martin et al. 1951).

Habitat: The Carolina chickadee, found in the southeastern forests, is a slightly smaller version of the black-capped chickadee. In Missouri, the Carolina chickadee nests south of the Missouri River across the Ozarks.

Nest: The nesting habits of black-capped and Carolina chickadees are pretty similar. They sometimes nest in natural cavities or abandoned holes left by woodpeckers, but usually, they dig their own nesting cavity in the rotting wood of dead tree trunks or branches from deciduous trees (Bent 1946). Black-capped and Carolina chickadees line their nests with fine grasses and feathers.

Food: The eating habits of the Carolina chickadee are very similar to those of the black-capped chickadee. Their diet includes insects as well as different types of fleshy fruits and seeds (Bent 1946).

Habitat: This species lives in pine and spruce forests at elevations between 7,000 to 10,000 feet within the United States, specifically in the Chiricahua Mountains of Arizona and the Animas Mountains of New Mexico (Phillips et al. 1964).

Nest: Mexican chickadees dig out nest cavities in dead trees or branches. One nest was discovered in a willow stub about 5 feet off the ground (Bent 1946).

Food: There was no information on diet available in the literature.

Habitat: This common little chickadee can be found in most coniferous forests of the West at elevations between 6,000 and 11,000 feet (Bent 1946).

Nest: Mountain chickadees typically nest in natural cavities or old woodpecker holes, and likely don't dig their own if there are suitable options available (Bent 1946). Winternitz (1973) noted five nests in live aspen and one in a dead aspen, located 6 to 15 feet off the ground. In Arizona, we’ve found five nests in live aspen, three in aspen snags, two in ponderosa pine snags, and one in a white fir snag.

Food: Insects likely make up a significant part of the diet (Bent 1946). Telford and Herman (1963) collected 10 birds in the Inyo National Forest, where there was an outbreak of lodgepole needle miners, and found 639 needle miner caterpillars in the stomachs of chickadees. Baldwin (pers. comm.[8]) examined the contents of 17 stomachs from the Wet Mountains, Colorado, and found that 75 percent of the summer diet consisted of insects. A large number of spruce aphids were present, along with flies, beetles, hymenopterans, and other insects. Plant material included seeds, spruce buds, and fruits. In southwestern Montana, during the summer, mountain chickadees fed on lepidopteran larvae, particularly cone worms and spruce budworms (DeWeese et al.[9][in prep.]), and insects accounted for about 98 percent of their diet.

Habitat: Broken forests or edges of aspen, willow, and spruce are the ideal habitat for the gray-headed chickadee. Its range is restricted to western Canada and Alaska.

Nest: Old woodpecker holes or natural cavities are chosen as nesting sites. Bent (1946) noted one nest located about 6 feet above the ground in a spruce snag.

Food: There isn't any information available in the literature about the eating habits of the gray-headed chickadee, but its diet is likely similar to that of other chickadees.

Habitat: The boreal chickadee is quite common in northern forests of spruce, fir, aspen, and birch (McLaren 1975).

Nest: Natural holes, old woodpecker digs, or spaces created by chickadees themselves are used for nesting (Bent 1946). McLaren (1975) found 22 nest holes, all in trees or snags with soft heartwood, and believed that the softness of the core, rather than a preference for a specific tree species, is the main factor in choosing a nest site.

Food: In the summer, the boreal chickadee eats caterpillars, moths, beetles, other insects, and insect eggs; it also feeds on birch cones, seeds, and cedar berries in the fall and winter (Bent 1946).

Habitat: Coniferous forests in the humid coastal region from Alaska to central California are the preferred habitat, but this bird can also be found in nearby deciduous woodlands and along streams (Peterson 1961, Grinnell and Miller 1944).

Nest: This species makes its nests in old woodpecker holes or in cavities that the bird carves out itself. Nests have been discovered in dead pine, oak, and Douglas-fir trees (Bent 1946).

Food: The diet consists of about 65 percent animal and 35 percent plant matter. Of the animal content, 25 percent is hemipterans, 18 percent caterpillars, 13 percent wasps, 7 percent spiders, and 2 percent beetles. Seeds and fruits make up the plant material (Beal 1907).

Habitat: The tufted titmouse is the largest North American titmouse and is frequently found in eastern deciduous woodlands. These energetic and chatty birds usually live in groups of 2 to 6 in dense forests, often close to water (Gillespie 1930). The black-crested titmouse, which is located in southern Texas and northeastern Mexico, is now regarded as the same species as the tufted titmouse (33rd supplement, A.O.U. Checklist).

Nest: Finding nests of the tufted titmouse is quite challenging and they're rarely mentioned in the literature. Reports suggest that these birds nest in old woodpecker holes or natural cavities typically under 20 feet off the ground. While titmice are very noticeable in late fall and winter, they often vanish in late spring to nest and molt (Gillespie 1930, Laskey 1957).

Food: The diets of tufted titmice change with the seasons. In spring and summer, they mainly eat animal matter (89 percent and 82 percent respectively) and spend most of their feeding time in the treetops. Caterpillars often make up over 50 percent of their animal diet. Common winter foods include beechnuts, acorns, dogwood berries, Virginia creeper berries, alder seeds, honeysuckle, and seeds from tulip-tree pods. In winter, they spend a larger percentage of their feeding time on or near the ground (Gillespie 1930, Martin et al. 1951).

Habitat: Oak and pinyon-juniper woodlands at elevations between 5,000 and 7,000 feet, stretching from Oregon down and across to Texas and New Mexico, are the preferred habitat of the plain titmouse.

Nest: Plain titmice typically nest in natural cavities or old woodpecker holes. Most reported nests have been found in oak trees, 2 to 23 feet above ground (Bent 1946). They utilize nest boxes when they are available (Wetmore 1964).

Food: Beal (Bent 1946) studied the contents of 76 stomachs and discovered that 43 percent of the material was animal-based (12 percent true bugs, 11 percent caterpillars, 7 percent beetles, 6 percent ants and wasps, 5 percent daddy longlegs and grasshoppers, 1 percent spiders, and 1 percent unreported) and 57 percent was plant-based (32 percent cherries, larger fruit pulp, and leaf galls, and 25 percent seeds from poison oak and weeds).

Habitat: Bridled titmice prefer chaparral and pinyon-juniper in the Southwest at elevations between 5,000 and 7,000 feet. This titmouse also inhabits areas along streams where cottonwoods are found (Phillips et al. 1964).

Nest: Nearly all nest sites have been documented in natural cavities of dead and living oak trees ranging from 4 to 28 feet above the ground (Bent 1946).

Food: There was no information found, but the diet is likely similar to that of other members of this genus. They all live in similar environments and spend a lot of time searching in the bark's crevices, on the trunks, and on branches, likely looking for adult insects, larvae, and eggs (Bent 1946).

Habitat: White-breasted nuthatches don’t migrate in most types of forests in the United States. They prefer deciduous woodlands. In the Rocky Mountains, they are most commonly found below an elevation of 9,500 feet (Bailey and Niedrach 1965).

Nest: White-breasted nuthatches mostly nest in natural cavities in living trees found in mature forests. If natural cavities aren’t available, they might use an old woodpecker hole (Kilham 1968b). In the West, nests have been discovered in dead aspens and in dead parts (from lightning strikes) of live ponderosa pines (Bailey and Niedrach 1965, Scott and Patton 1975). The nests are lined with hair and feathers and are often reused for more than one year.

Food: A variety of insects, including gypsy moth larvae, forest tent caterpillars, beetles, spiders, caterpillars, and ants make up the main diet of white-breasted nuthatches during spring and summer. In winter, their diet mostly consists of mast, which includes beechnuts, acorns, hickory nuts, corn, and sunflower seeds (Bent 1948). The insect foods also include several other forest pests like nut weevils, locust seed weevils, and roundheaded woodborers (Scott and Patton 1975). Nuthatches may also be drawn to feeders that offer suet and sunflower seeds.

Habitat: Red-breasted nuthatches nest in the high elevations of the Rocky Mountains and in the Canadian boreal forests. They occasionally migrate to the eastern forests during winter. In Colorado, they prefer habitats that consist of coniferous trees and aspens, ranging from the Canadian Life Zone to the timberline.

Nest: Red-breasted nuthatches will dig out their own cavity if they can’t find a natural one or a woodpecker hole that suits them (de Kiriline 1952). Nests are typically located 6 to 40 feet above the ground in decaying stubs or branches of dead trees. They’ve been found in birch, poplar, cottonwood, oak, and pine. Unlike white-breasted nuthatches, their nests usually aren’t lined.

Food: Not much is known about what red-breasted nuthatches eat. They primarily feed on seeds from pine, spruce, and other coniferous trees. Their diet also includes beetles, wasps, spiders, and ribbed pine borers. Occasionally, they eat flying insects (Bent 1948). In winter, these birds will visit feeders that provide suet.

Habitat: Brown-headed nuthatches prefer clearings and areas that have burned (because there are more old stumps available for nesting) in southern pine woods. They can also be found in mixed pine and hardwood forests in the extreme southeastern United States (Bent 1948).

Nest: Brown-headed nuthatches dig or partially dig nest cavities 4.5 to 8 inches deep in dead trees and stumps (often charred from fire) or in posts and poles. Bent (1948) provided little evidence that brown-headed nuthatches will use old woodpecker holes, but they might enlarge and use natural cavities. The nests are found 3 to 46 feet off the ground (only rarely above 13 feet). Since the nest entrances resemble a crack in a tree rather than having a rounded shape like a woodpecker hole, the nests are hard to spot (Pearson 1936).

Food: Brown-headed nuthatches primarily eat insects and are seen as important protectors of trees. They look for insects and their eggs in the cracks of bark on the trunks, branches, twigs, and needles of pine trees. They also consume pine seeds (Bent 1948).

Habitat: Pygmy nuthatches are commonly found in ponderosa pine forests across the West. They’re also present in Jeffrey pine, Bishop pine, and Monterey pine areas in California (Grinnell and Miller 1944), as well as in pinyon-juniper woodlands in Arizona (Phillips et al. 1964).

Nest: Almost all observed nests of the pygmy nuthatch have been found at heights ranging from 8 to 60 feet above the ground in holes dug by the bird itself in both dead and live pine trees (Bent 1948). We discovered 27 nests in ponderosa pine snags and two in dead aspens in the White Mountains of Arizona.

Food: Around 80 percent of their diet consists of animal matter, mainly wasps and spittlebugs, along with some ants, beetles, and caterpillars; the rest is almost entirely conifer seeds (Bent 1948).

Habitat: This unnoticeable small bird is quite common in the coniferous forests of the Transition and Canadian Life Zones. In Colorado, it breeds between 7,000 feet and the timberline (Bailey and Neidrach 1965). Creepers spend the winter in forests across the southern states.

Nest: Sometimes creepers make their nests in natural cavities and old woodpecker holes, but usually, they nest between the loose bark and the trunk of a large dead tree (Bent 1948). We found three nests behind the loosened bark of dead ponderosa pines and one in a white fir snag in the White Mountains of Arizona.

Food: Not much is known, but their diet mainly consists of insects, including weevils, leafhoppers, flat bugs, jumping plant lice, scale insects, katydid eggs, ants, and other small hymenoptera, sawflies, moths, caterpillars, leaf skeletonizer cocoons, codling moth pupae, spiders, and pseudoscorpions (Bent 1948). The little bit of plant material they consume is mostly nuts.

Habitat: House wrens are frequently found nesting in bushes and brush across the northern two-thirds of the United States, but they migrate to the southern states for the winter. They can be seen from the plains to the treeline in the Rocky Mountains. You often find them near the borders of woods, swamps, fields, and in orchards.

Nest: House wrens are aggressive when it comes to nesting and will chase other birds away from cavities. Nests have been found in various places, including 2-inch pipes used to support fence posts, nesting boxes, natural cavities, and holes made by downy woodpeckers (Sutton 1930). Nests are generally less than 10 feet off the ground. The entrance hole in nesting boxes should be 1 inch in diameter.

Food: House wrens can eat a lot of insects and arthropods, which make up 98 percent of their diet. Their diet includes beetles, caterpillars, bugs, grasshoppers, and ants (Bent 1948).

Habitat: Brown-throated wrens live in oak forests, primarily in desert areas, but can be found at elevations of up to 8,000 feet in southern Arizona.

Nest: This wren uses natural nooks or old woodpecker holes in tree trunks or branches. Similar to the house wren, it occasionally takes over spaces around buildings and in nest boxes (Pough 1957).

Food: We couldn’t find any published information on food habits, but the diet is likely insects, similar to that of other wrens.

Habitat: Winter wrens live in coniferous forests of spruce, fir, and pine, as well as in the underbrush of woodlands in the eastern and western United States and Canada.

Nest: Winter wren nests, made from twigs and leaves, are built near the ground in exposed roots, fallen logs, or in rocks and crevices (Bent 1948, Wetmore 1964).

Food: Information on food items wasn't located in the literature, but the diet likely consists of adult and larval stages of insects (Bent 1948).

Habitat: Bewick’s wrens are common and widespread in the West, but less common and localized in the Appalachians and Ozarks. They are typically found in farmyards, brushlands, fencerows, and suburban areas. Bewick’s wrens are quite common in pinyon-juniper forests and in mesquite-willow-cottonwood areas along southwestern streams.

Nest: Nests of the Bewick’s wren can be found in many different places. Most nests are shaped like cups and can be either open on top or closed. They’re typically situated in cavities near the ground (Miller 1941). Nest sites include natural cavities, woodpecker holes, knotholes in fallen trees, fence posts, tin cans, bird boxes, and abandoned cars (Bent 1948).

Food: Bewick’s wrens, like other wrens, consume a significant amount of insects that harm plants. Ninety-seven percent of their diet consists of insects, mainly hemiptera and coleoptera. In the South, they are known for eating boll weevils (Bent 1948).

Habitat: Carolina wrens are commonly found in forest areas with dense underbrush across the eastern United States. The number of individuals in northern populations varies significantly based on the severity of winter weather.

Nest: Carolina wrens are quite versatile in their choice of nesting sites. These wrens prefer nesting areas that are relatively well enclosed, but they don’t solely rely on cavities. They are well adapted to the conditions created by humans, but they also nest in forests where they like tangles and bushy undergrowth. Nests have been found in natural cavities, mailboxes, newspaper tubes, old hornet nests, and birdhouses (Laskey 1948, Nice and Thomas 1948).

Food: The Carolina wren's diet consists mostly of animal food, primarily insects, which make up 93 percent of what they eat. Within this, beetles, caterpillars, and moths are the largest contributors. The remaining 7 percent is plant material, mainly seeds collected in the winter. Because Carolina wrens typically forage on or near the ground, deep snow can be harmful to their survival. They will go to feeding stations if they're set up near brush piles (Bent 1948).

Habitat: In their natural environment, eastern bluebirds prefer to use cavities in savannah-like habitats east of the Great Plains (Rustad 1972). They are an edge species, so they don’t thrive in dense forests or crowded residential areas (Thomas 1946). Similar to purple martins, bluebirds have made use of nest boxes placed in farming areas, near open fields, and in orchards.

Nest: Eastern bluebirds often lose their nesting sites (snags) because they're seen as unattractive or they interfere with farming. When available, eastern bluebirds nest in old woodpecker holes, decay hollows in trees, and crevices in rocks (Pearson 1936). They will easily utilize hollows in wooden fence posts or properly sized and positioned nest boxes (5 × 5 × 8 inches high with a 1.5-inch hole located 6 inches from the bottom). Boxes should be placed 5 to 10 feet above the ground at the edge of a clearing in the forest or field.

Food: Eastern bluebirds eat 70 percent animal matter and 30 percent plant matter. Their plant intake goes up to over 50 percent in December and January, but drops to zero in May. The animal matter consists of grasshoppers, crickets, and katydids, different types of beetles, moths and caterpillars, some wasps and true bugs, along with various other invertebrates and small vertebrates. The plant matter mainly consists of wild fruits (Bent 1949).

Habitat: The western bluebird is most common in open ponderosa pine forests of the Transition Zone, but it can also be found in oak woodlands, pinyon-juniper, mixed conifer, and subalpine forests.

Nest: Nests are typically found in old woodpecker holes, but this bird also uses natural cavities. Nests have been reported in oak, sycamore, and pine trees. In Monterey County, California, nests were located between 5 and 40 feet above ground in pine stumps or trees (Bent 1949). This bluebird, similar to the eastern type, also easily nests near humans in birdhouses. Nest boxes should measure 5 × 5 × 8 inches with a 1.5-inch entrance hole placed 6 inches from the floor. Boxes should be situated 5 to 10 feet above ground near forest openings or meadows.

Food: Beal (Bent 1949) looked at the contents of 217 stomachs and discovered that 72 percent was animal material (21 percent grasshoppers, 20 percent caterpillars, 9 percent beneficial beetles, 16 percent other beetles, 5 percent ants, and 1 percent other hymenoptera) and 28 percent was plant material, mainly wild fruits like elderberries, mistletoe berries, blackberries or raspberries, prunes, cherries, and a few weed seeds.

Habitat: The mountain bluebird nests in almost all types of forests in the Rocky Mountain region and has been observed at elevations ranging from 800 to 11,000 feet in Idaho (Burleigh 1972). However, this species typically lives between 7,000 and 11,000 feet in open forests or near the edges of forests.

Nest: The mountain bluebird typically nests in natural cavities or in old woodpecker holes, but it also uses man-made structures. Nests have been found in fir and pinyon snags as well as aspen trees (Burleigh 1972, Bent 1949). We observed six nests in the White Mountains of Arizona, ranging from 12 to 35 feet above the ground in ponderosa pine snags. Five of these were in abandoned woodpecker holes, and one was in a natural cavity. Nest boxes should be similar to those used for other bluebirds.

Food: This is likely the most insect-eating bluebird. Studies show that almost 92 percent of its diet consists of animal matter, including various beetles, weevils, ants, bees, wasps, cicadas, stinkbugs, black bugs, assassin bugs, jassids, flies, caterpillars, grasshoppers, locusts, and crickets (Bent 1949). The plant-based items include currants, grapes, elderberries, sumac seeds, mistletoe berries, hackberry seeds, Virginia creeper seeds, and cedar berries.

Habitat: Starlings breed in a variety of habitats that provide enough food for their young (Troetschler 1976), but they are probably most common in suburban and rural areas where there are plenty of suitable nesting sites. Kalmbach (1928) pointed out that starlings tend to prefer densely populated agricultural regions and noted that “They are partial to human association....” After they were introduced to the United States, starlings initially settled in lowland areas and continue to thrive there (Small 1974, Royall 1966, Bent 1950). In a study in southeast Ontario, starlings favored old field habitats over five other types when there were enough nesting sites available (Gibo et al. 1976).

Nest: Trees, telephone poles, fence posts, drainpipes, mailboxes, buildings, haystacks, and cliffs have all been used for nesting, as well as burrows and open nests from other species (Kessel 1957, Bent 1950). Natural nesting spots seem to be favored over nest boxes (Planck 1967). When it comes to competition for nesting cavities, starlings usually have the advantage over native species, but most native species seem to breed in areas where starlings aren't very common.

Food: An analysis of the contents of 2,750 starling stomachs collected in the northeastern states revealed that 57 percent consisted of animal materials, including insects, millipedes, spiders, mollusks, and a few crustaceans. Insects like weevils, ground beetles, and plant-feeding scarab beetles, like May beetles, were particularly significant. Among the 43 percent of vegetable material, wild fruit was the most important, but cultivated cherries, vegetables, grains, and various seeds were also consumed (Kalmbach 1928). In different regions, starlings also eat grapes, blueberries, figs, and other fruits, as well as truck crops, sprouting crops, and prepared livestock feed.

Habitat: The crested myna is originally from the plains and lowlands of cultivated southern China and was brought to Vancouver, B.C., Canada in the 1890s. While mynas have been spotted in Washington and Oregon, the majority of the population is found in Greater Vancouver and Vancouver Island. Mynas seem to thrive in urban areas and nearby open fields (Mackay and Hughes 1963).

Nest: In cities, mynas will nest in just about any enclosed space, including birdhouses meant for other birds. In forested regions, they seem to prefer holes created by flickers and other woodpeckers (Bent 1950).

Food: Scheffer and Cottam (1935) looked at the stomach contents of 117 adult mynas and found that 39 percent was animal matter and 61 percent was plant matter. The animal matter included flies, moths, caterpillars, wasps, bees, ants, bugs, beetles, grasshoppers, spiders, and earthworms. The plant matter consisted of wild types of elderberries, cherries, blueberries, crowberries, snowberries, salmonberries, loganberries, and serviceberries. They also ate fruits from cultivated cherries, strawberries, raspberries, and blackberries, and caused some damage to apples, pears, cabbages, and lettuce.

Habitat: The prothonotary warbler is found south of Canada in the eastern deciduous forests of the United States. Other names for this warbler, like golden swamp warbler and willow warbler, highlight its preference for swamps and periodically flooded areas. The prothonotary often lives near running water alongside streamside willows (Pearson 1936).

Nest: Nests are usually found in stumps and snags either standing in or near water (Simpson 1969) and often leaning over the water (Pearson 1936). Downy woodpecker and chickadee holes typically range from 2 to 12 feet above the ground, with an average height of 5 feet (Pearson 1936). However, the warbler is said to be quite flexible regarding the types of nesting cavities it uses. Prothonotaries sometimes even nest in birdhouses and close to buildings (Forbush and May 1939).

Food: Prothonotary warblers mainly eat insects. Their diet includes ants, spiders, beetles, mayflies, and their larvae. They also consume the larvae of aquatic insects. This warbler forages on the trunks and branches of trees, shrubs, and fallen logs. They will also sit on tall grasses and water plants to eat small mollusks (Bent 1953).

Habitat: This warbler lives in mesquite woodlands and along rivers with willows and cottonwoods, ranging from Nevada to the southwestern United States.

Nest: Lucy’s warblers typically build their nests in tree cavities or under loose bark in willows, cottonwoods, and mesquite. They also use ironwood, palo verde, and catclaw as nesting trees (Robbins et al. 1966, Bent 1953, Peterson 1961).

Food: Insects are the main food sources in the diet of Lucy’s warbler (Bent 1953).

Habitat: House sparrows are well-known companions of humans, thriving in cities and urban areas. They also inhabit suburban and rural landscapes (Summers-Smith 1963). Their ideal habitat is often found around buildings where leftover grain from poultry and livestock feeding is available. This species is rare or missing in densely forested and desert areas that are uninhabited by humans (Kalmbach 1940).

Nest: House sparrows build their nests in eaves, crevices, and holes in buildings; in vines and creeping plants on walls; in tree branches; in nest boxes and natural cavities in trees; and in various other places, likely in that order of importance. Open tree nests tend to be constructed more frequently in warmer areas, but females seem to prefer nests in holes (Cink 1976). Nesting spots of cliff and bank swallows and house finches might be taken over. Nests are typically at least 6 to 8 feet off the ground and can be as high as 50 feet, with groups or colonies being quite common. Nests are domed whether they're in cavities or out in the open. House sparrows readily use birdhouses meant for purple martins, bluebirds, and other species.

Food: Kalmbach’s (1940) study of the stomach contents of 4,848 suburban and rural birds showed that adult and juvenile (non-nestling) house sparrows consume 3.4 percent animal material throughout the year, mainly dung beetles, May beetles, and other Scarabaeidae. Grain from poultry yards and similar sources made up the largest portion of their plant-based diet (31.5 to 84.2 percent), followed by seeds from grasses and weeds (17 percent), and oats not included in feed (14.4 percent). Important plants in the grasses and weeds category included ragweed, crabgrass, smartweed, and pigweed.

Habitat: The European tree sparrow was brought to St. Louis, Missouri, in 1870. As house sparrows became more common, European tree sparrows moved away from heavily populated areas in St. Louis and set up populations on the outskirts of the city, in suburban areas, farmyards, and woodlots. The species now occupies about 8,500 square miles in extreme east-central Missouri and west-central Illinois. They seem to be gradually extending their range northward in western Illinois (Barlow 1973).

Nest: European tree sparrows nest in natural cavities, crevices, and woodpecker holes. They seem to be at a disadvantage when it comes to competing for available nesting spots. One reason for the tree sparrow's expanding range to the north might be the significant number of dead and dying American elms (victims of Dutch elm disease) that have created more nesting opportunities (Barlow 1973).

Food: Tree sparrows mainly eat from the ground, feeding on weed seeds, corn, insects, and spiders.

★ U.S. GOVERNMENT PRINTING OFFICE: 1977 O-246-764