Cooper's hawks are native to the Nearctic and Neotropical regions. They can be found throughout southern Canada and the United States. They winter as far north as the northern United States and southern Ontario, and as far south as Costa Rica.

Biogeographic Regions: nearctic (Native ); neotropical (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) BREEDING: southern British Columbia across southern Canada to central Saskatchewan, southern Quebec, and the Maritime Provinces, south to Baja California, northern Mexico (Chihuahua, Nuevo Leon), and southeastern U.S., though basically absent from the western Great Plains (AOU 1983, Rosenfield and Bielefeldt 1993). NON-BREEDING: Washington, Rocky Mountain states, southern Minnesota, southern Ontario, and New England south to Middle America (commonly to Honduras, rarely but regularly to Costa Rica, casually to Colombia) (AOU 1983, Stiles and Skutch 1989, Johnsgard 1990, Rosenfield and Bielefeldt 1993).

Cooper's hawks are medium-sized birds with long, lean-bodies. Individuals in the western part of the range tend to be smaller than those in the east. Male length ranges from 35 to 46 cm and length of female ranges from 42 to 50 cm. The average mass of males ranges from 280 g in western males to 349 g for eastern males. The average mass of females ranges from 439 g for western females to 566 g for eastern females. Cooper's hawks have a wingspan of 75 to 94 cm.

Adult Cooper's hawks have a dark blackish crown that is noticeably set off from a lighter nape. They have a blue-gray back and a tail that is crossed by several dark bands and has a distinct white band at its tip. In flight, Cooper's hawks exhibits a long barred tail and rather short and rounded wings.

The eyes of this hawk, like most predatory birds, face forward, giving it good depth perception for hunting and catching prey while flying at high speeds. The hooked bill is well adapted to tearing the flesh of prey. A swift flyer, the Cooper's hawk has a rapid wingbeat and is able to negotiate heavily vegetated woodland habitats.

Cooper's hawks can be easily confused with sharp-shinned hawks, which are smaller (25 to 35 cm) and have a less distinct dark crown and a tail that is square at the tip, unlike the rounded tip of the Cooper’s hawk’s tail. Cooper’s hawks also exhibit slower, stiffer wingbeats than sharp-shinned hawks.

Range length: 35 to 50 cm.

Average length: 39 cm.

Range wingspan: 74 to 94 cm.

Sexual Dimorphism: female larger

Average mass: 526.64 g.

Length: 51 cm

Weight: 529 grams

Differs from sharp-shinned hawk (Accipiter striatus) by longer, more rounded tail that has a wider white terminal band; larger head; and (in adult) stronger contrast between the dark crown and paler nape and back. Differs from goshawk (Accipiter gentilis) in smaller size (average length 36-51 centimeters vs. 53-66 centimeters), lack of conspicuous pale eyebrow, less conspicuous white undertail coverts, broader white tip on tail, and proportionately longer tail and shorter wings (NGS 1983).

• Terrestrial

Coopers hawks are closely associated with deciduous and mixed forests and open woodland habitats such as woodlots, riparian woodlands, semiarid woodlands of the southwest, and other areas where the woodlands occur in patches.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: savanna or grassland ; chaparral ; forest

Other Habitat Features: suburban ; riparian

Comments: BREEDING: Primarily mature forest, either broadleaf or coniferous, mostly the former; also open woodland and forest edge (AOU 1983). Nests in both pine and hardwood groves, and riparian cottonwoods and sycamores in the West; Douglas-fir in northeastern Oregon. Usually builds new nest on horizontal limb near trunk or in crotch, 6-18 meters above ground; may modify old one or squirrel or crow nest. Campbell et al. (1990) reported one instance of a nest being reused for six consecutive years in British Columbia. Rosenfield and Bielefeldt (1992) found that nesting areas were irregularly reused by the same or different adults in subsequent years.

Generally is an inhabitant of deep woods, utilizing thick cover both for nesting and hunting. Openings, especially where hedgerows or windbreaks offer shelter for prey species, may also be used when foraging. Johnsgard (1990) states that Cooper's are less fussy about the forest type than sharp-shins, and are more often "associated with deciduous and mixed forests and open woodland habitats such as woodlots, riparian woodlands, semiarid woodlands of the southwest, and other areas where the woodlands tend to occur in patches and groves or as spaced trees."

In the Northwest and Northeast, conifers are used for nesting (Bent 1937, Reynolds et al. 1982), but elsewhere the preference is for hardwoods (Brown and Amadon 1968). In the Northwest a preference may exist also for the cooler microclimates offered by north and east facing slopes (Reynolds et al. 1982). In that area, the Cooper's hawk is typically found in middle-aged stands, 50 - 60 years in age, whereas the sharp-shin prefers younger stands and the goshawk older ones (Reynolds et al. 1982). That difference might express competitive displacement, because in the East, where the goshawk rarely nests, the Cooper's hawk prefers mature stands (Brown and Amadon 1968).

In some areas the species seems to require large tracts of forests and to avoid human contact, in others they may use small forest tracts, (e.g., British Columbia and Nevada), woodlots (e.g., Ohio) or urban/suburban areas where they seem tolerant of human activities (e.g., British Columbia, Utah, Wisconsin, Indiana) (Hennessy 1978, Herron et al. 1985, Campbell et al 1990, Peterjohn and Rice 1991, Rosenfield et al. 1991).

In New Jersey-New York, nested mostly in mixed deciduous-coniferous forest with eastern hemlock the dominant coniferous species at many sites. Tended to nest in areas with relatively large basal area and more canopy cover. Nests located in live overstory trees (43% conifers), typically within the canopy, and always in dense forest but commonly near wetland openings or source of water, on level ground or lower slopes, typically several hundred meters from paved roads (but sometimes within 100 meters or less). Avoided southern exposures (Reynolds et al. 1982, Bosakowski et al. 1992).

A recent study in Missouri documented numerous Cooper's Hawks nesting in young pine plantations in essentially the same habitat as sharp-shins. Also found that trees with deformed crowns were preferred (Wiggers and Kritz 1991). Rosenfield et al. (1991) report that pine plantations are important habitat for breeding Cooper's hawks throughout the Midwest, and particularly in Wisconsin. See Kennedy (1988) for details on nesting habitat in New Mexico.

NON-BREEDING: Migrates mostly along ridges and coastlines (NGS 1983). Winter habitat is much the same as in the nesting season, although open woodlands and fields may be utilized to a greater extent.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

Northernmost populations migratory (move north mostly March-April, southward late August-early November) but regularly present throughout most of breeding range in winter. Migrates singly or in twos or threes (National Geographic Society 1983). See Palmer (1988) for more information.

Cooper's hawks are predators primarily of birds and small mammals. They also occasionally feed upon reptiles and amphibians. When hunting, Cooper's hawks usually perch in a hidden location and watch for prey. They wait until their prey is unaware of their presence, then quickly swoop down and seize it. Bobwhites, starlings, blackbirds, chipmunks, and squirrels are common prey for Cooper's hawks. Their short, rounded wings make them very maneuverable flyers in dense, forested habitats. These hawks also pursue prey on the ground, half running and half flying. The prey taken by an individual Cooper’s hawk is largely influenced by the size of the bird; larger hawks eat larger prey than smaller hawks.

There is no information available regarding how Cooper's hawks obtain water.

Animal Foods: birds; mammals; amphibians; reptiles

Primary Diet: carnivore (Eats terrestrial vertebrates)

Comments: Eats medium-sized birds (e.g., starling, thrush, quail), sometimes small birds and some up to size of adult ruffed grouse, small ground-foraging mammals, occasionally reptiles (especially in southwestern U.S.) and amphibians. Their primary food is other birds; up to 90% of its diet is composed of avian prey, with mid-sized birds such as flickers and starlings being taken preferentially (Kennedy 1980). They are frequently important predators of bobwhites and were at least formerly, before the days of factory farming, raiders of domestic fowl. These food choices have led to a great deal of persecution by humans. Additional foods include small mammals, reptiles, amphibians, and insects (Bent 1937). In the southwest and west mammals and lizards can make up as much as half the food intake (Johnsgard 1990). Young birds comprise a large proportion of the food provided to nestlings. Typically hunts from inconspicuous perch, or uses a longer searching flight. Sometimes attracted to birds at feeders. Birds may not necessarily prevail in the diet (Bielefeldt et al. 1992).

Cooper's hawks impact the populations of the animals they prey on. They are also hosts for several species of parasites, including larval dipterans, mallophagial lice, tapeworms and helminths.

Adults, nestlings and eggs are vulnerable to predation by great horned owls, red-tailed hawks and northern goshawks. Eggs and nestlings are also vulnerable to predation by raccoons and American crows.

Known Predators:

• red-tailed hawks (Buteo jamaicensis)
• northern goshawks (Accipiter gentilis)
• raccoons (Procyon lotor)
• American crows (Corvus brachyrhynchos)
• great horned owls (Bubo virginianus)

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 to >300

Comments: Numerous occurrences but precise number is unknown.

10,000 - 100,000 individuals

Comments: No rangewide estimates. Number of breeding pairs in Canada in the early 1990s was estimated at 10,000-50,000 (Kirk et al. 1995). Johnsgard (1990) ventured a minimum wintering population estimate, based on the 1986 Audubon Christmas Counts, of 19,400 Cooper's hawks in the United States and Canadian provinces. The maximum bird populations he estimated were in Arizona (3,250 birds) and California (3,200 birds). The number wintering south into Central America is unknown.

Few data on population densities exist. Craighead and Craighead (1956) found 1554 hectares per pair in 1947-1948 in Michigan. In Maryland a density estimate of 200 hectares per pair was calculated by Stewart and Robbins (1958). Rosenfield et al. (1991) compiled nesting densities from various studies. These densities ranged from a low of 5000 hectares per pair in North Dakota in 1987, to a high of 331 hectares per pair in a pine plantation in southeastern Wisconsin in 1986.

Strongly territorial. Males vigorously defend an area 30 meters in diameter around the nest site although they may forage up to 3.2 kilometers away (Brown and Amadon 1968). Johnsgard (1990) reported home range sizes that ranged from 105 to 784 hectares (the latter was seasonal home range; daily home range was 231 hectares). Nests are typically spaced 2.4 - 5.6 kilometers apart (Brown and Amadon 1968, Reynolds and Wight 1978, Kennedy 1980, Campbell et al 1990) and not usually less than one kilometer apart (Palmer 1988). The smaller sharp-shinned hawk also appears to keep similar distances from Cooper's hawk nests (Brown and Amadon 1968, Reynolds and Wight 1978), indicating interspecific aggression probably related to competition for food. Winter range is larger. Michigan birds ranged over areas of 2.4 - 3.2 kilometers in diameter.

Dispersal range is limited. In Wisconsin, six males dispersed 4 - 35 kilometers (mean 12 kilometers) from natal site to nesting site; one female dispersed 14 kilometers (Rosenfield and Bielefeldt 1992). Hunt by a combination of still-hunting and searching flights along woodland edges and natural routes (Johnsgard 1990).

Birds following inland migration routes apparently migrate over longer distances than those following coastal routes, and tend to have longer wings and tails, creating lower "flight-surface loading." This is thought to be an adaptation to the longer flight distances, more open country, and stronger thermal updrafts encountered along the inland routes (Smith et al. 1990).

Mortality appears to be quite high during the birds' first winter, approaching 78% as opposed to only 34% per year for the adults 2 to 8 years old (Henny and Wight 1972). The maximum recorded lifespan is 8 years (Henny and Wight 1972). Life history traits place it intermediate for population turnover rate between the larger goshawk and smaller sharp-shinned hawk. This may partially explain the slower recovery of Cooper's from a population crash in the 1950s-1960s compared to sharp-shinned hawks (Bednarz et al. 1990).

Cooper's Hawks communicate using vocalizations and displays. They probably use vocalizations more than visual displays, because their dense forested or woodland habitat prevents visual displays from being seen very far away. One study recorded 42 different calls made by females, 22 by males, and 14 by juveniles. Males have higher pitched voices than females.

Communication Channels: visual ; acoustic

Cooper's Hawks are known to live as long as 12 years in the wild. However, one study showed that the average age at death was as low as 16.3 months for wild Cooper's hawks.

Range lifespan

Status: wild: 12 (high) years.

Average lifespan

Status: wild: 1.3 years.

Average lifespan

Status: wild: 244 months.

Cooper’s hawks are monogamous, and many pairs mate for life. Pairs breed once per year and raise one brood per breeding season. The male chooses the nest site, but the female does the majority of the nest-building. Courtship activities include stylized flights with the wings held in a deep arc. Cooper’s hawks are territorial, and defend a territory around the nest.

Courtship activities include flight displays. For example, the male of a pair will fly around the female exposing his expanded under tail coverts to her. The male raises his wings high above the back and flies in a wide arc with slow, rhythmic flapping. Typically these display flights occur on bright, sunny days in midmorning, and begin with both birds soaring high on thermals. The male and female may both participate in courtship flights. The male begins by diving toward the female, followed by a very slow-speed chase. Both birds move with a slow and exaggerated wingbeats alternated with glides in which the wings are held at a dihedral angle and the white under tail coverts are conspicuously spread.

Mating System: monogamous

Cooper's hawks begin breeding as early as March. Most individuals do not breed until they are at least two years old. Pairs build nests made of sticks and twigs and lined with bark, conifer needles and down. Males select most of the nest materials and do most of the nest building, although females contribute pieces of material occasionally. The female lays 3 to 6 (usually 4 to 5) bluish to greenish-white eggs that are usually spotted and soon become stained in the nest. The eggs hatch after 32 to 36 days, during which time they are incubated primarily by the female. During this time, the male provides most of the food for the female. After the eggs hatch, both parents tend the young who leave the nest after 27 to 34 days. Parents continue to provide food until the young become independent at about 8 weeks.

Breeding interval: Cooper's hawks breed once yearly

Breeding season: Cooper's hawks begin breeding as early as March.

Range eggs per season: 3 to 6.

Range time to hatching: 32 to 36 days.

Range fledging age: 27 to 34 days.

Average time to independence: 2 months.

Range age at sexual or reproductive maturity (female): 1 (low) years.

Average age at sexual or reproductive maturity (female): 2 years.

Range age at sexual or reproductive maturity (male): 2 (low) years.

Average age at sexual or reproductive maturity (male): 2 years.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)

Average eggs per season: 4.

Both male and female Cooper’s hawks care for their chicks. During incubation, the female spends most of the time protecting the eggs and nest, and the male provides nearly all of her food. After hatching, both parents tend the young. The male continues to do most of the hunting during the hatchling stage. Both parents continue to provide food to the chicks until they become independent at about 8 weeks.

Parental Investment: altricial ; pre-fertilization (Provisioning); pre-hatching/birth (Provisioning: Male, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)

The breeding season usually begins in early April and extends through May and June (Bent 1937, Brown and Amadon 1968). The annual molt begins in late June but can occur as late as October (Bent 1937). Southward migration commences in the northern states in late August, with September being the peak month; it is essentially over by November. Northward migration occurs from late February to early April (Brown and Amadon 1968).

The male does most of the nest building and occasionally some of the incubation; most of the incubation is done by the female, which seldom leaves the nest before the young have fledged (Brown and Amadon 1968). During the pre-fledging period the male provides both the female and the young with food, while both parents feed the young for up to four weeks after they leave the nest (Brown and Amadon 1968).

Only one brood is raised each year. The normal clutch is four-five eggs, with clutches of three and six being rarely observed (Bent 1937). A national average has been calculated at 3.5 eggs (Bednarz et al. 1990). Replacement clutches are laid if the first set is lost, and laying can be delayed under conditions of low food availability (Bent 1937, Snyder and Wiley 1976).

Hatching success data are limited, but in areas unaffected by DDT contamination the average hatching rate ranges from about 70% to 83% (Craighead and Craighead 1956, Johnsgard 1990), with some further reduction in the brood occurring after hatching. Normal fledging success rates range from 2.1 to 3.5 for pairs with successful nests (Craighead and Craighead 1956, Schriver 1969, Henny and Wight 1972, Reynolds and Wight 1978, Herron et al. 1985); roughly 80% of nests produce at least one fledgling (Henny and Wight 1972). In areas affected by DDT poisoning these figures were reported to be dramatically reduced.

The young fledge one month after hatching, the males leaving the nest three-four days earlier than the larger females. They remain dependent on their parents until they are eight weeks of age and have learned to forage on their own (Brown and Amadon 1968). Only about 19% of the birds breed in their first year. Most nest by the second year and continue breeding throughout the rest of their lives.

Cooper’s hawk populations declined as a result of the use of pesticides such as DDT, but have begun to recover since DDT was banned in 1972. One threat facing Cooper’s hawks today is degradation and loss of habitat. Management activities such as logging may make former habitat unsuitable for breeding.

Cooper's hawks are protected under the U.S. Migratory Bird Act and CITES Appendix II. They are listed under CITES Appendix III in Costa Rica. In Michigan, they are listed as a species of special concern.

US Migratory Bird Act: protected

US Federal List: no special status

CITES: appendix ii

State of Michigan List: special concern

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N4N,N5B : N4N: Apparently Secure - Nonbreeding, N5B: Secure - Breeding

United States

Rounded National Status Rank: N5B,N5N : N5B: Secure - Breeding, N5N: Secure - Nonbreeding

Rounded Global Status Rank: G5 - Secure

Reasons: Large breeding range throughout the forested portions of the contiguous U.S., southern Canada, and northern Mexico; populations have stabilized or are increasing in some parts of range, but the species has not fully recovered from the drastic decline of the period 1940-1970+ throughout much of the eastern part of the range; reasons for this lack of recovery are unknown; potentially threatened by the use of organochlorine biocides in Central America and locally by habitat loss.

Global Short Term Trend: Relatively stable (=10% change)

Comments: Although some local, short-term studies indicate declines, Mosher (1989) believed that migration counts indicated that Accipiter populations were stable or increasing in the eastern U.S. Mosher (1989) also pointed to the facts that the Cooper's hawk was consistently found as a breeding species in intensive studies of woodland hawks in the Northeast, and that productivity and nest success in these studies indicated healthy populations, to support his claim that this species' rarity and vulnerability have been exaggerated. Rosenfield et al. (1991) emphasized that currently available information was inadequate to establish the status of the Cooper's hawk in most of the Midwest. In Wisconsin, however, they believed that they had adequate data to establish that the species should not be classified as "threatened." Nevertheless, even if Cooper's hawk populations have stabilized in the Northeast and parts of the Midwest, this species is clearly much rarer today across much of the eastern half of its range than it was a century ago. In the West, the species is generally considered stable, though California's population apparently declined in recent decades (Remsen 1978, California'sWildlife 1990). Ehrlich et al. (1992) stated that numbers in southeastern New Mexico and Arizona were declining in 1988. Most recent information indicates a stable or increasing population in Canada (Kirk et al. 1995). Data currently available provide only minimal evidence of trends. The paucity of clear data on trends supports the conclusion that state protection status for the Cooper's hawk is largely based on conservative speculation at present (Mosher 1989, Rosenfield et al. 1991). The population as a whole appears to be fairly stable. However, the species is declining in some areas (e.g., California), and at the same time increasing in some of the states where the population declined precipitously during the era of widespread organochlorine pesticide use.

Global Long Term Trend: Decline of 30-50%

Comments: Population declined noticeably from the 1940s until at least the 1970s. Some areas have partly recovered, but population size is still much lower over most of eastern range than prior to the decline. The population declined at an estimated 13.5 percent per year from 1941 to 1945, and at a rate as high as 25 percent per year after 1948 when DDT came into widespread use (Henny and Wight 1972). Since 1968 the reproduction rate and population size improved in at least some areas of the Cooper's hawk's range. For example, Ohio reported rapid recovery of this species in the 1980s (Peterjohn and Rice 1991). Bednarz et al. (1990) noted a period of decline between 1950 and 1964, followed by a gradual increase continuing through 1986. Population levels had not returned to pre-DDT era by 1986. A significant increase was recorded in migration counts in northeastern North America, 1972-1987 (Titus and Fuller 1990).

Degree of Threat: B : Moderately threatened throughout its range, communities provide natural resources that when exploited alter the composition and structure of the community over the long-term, but are apparently recoverable

Comments: Major threats are pesticide use (especially chlorinated hydrocarbons used in Central America) and loss of habitat. Sometimes shot by hunters and farmers, or nests are robbed by falconers. PESTICIDES: The principal cause for the population crash since the 1950s has been nesting failure due to DDT poisoning. A severe decline in the eastern portion of the range was first noted in counts of migrating populations during the 1960s (Peterson 1964, Spofford 1969, Nagy 1977). More direct evidence for the role of pesticide poisoning includes observations of drastically reduced fledging success rates (Schriver 1969), reductions in egg-shell thickness (Anderson and Hickey 1972), and a strong correlation between egg-shell thinning and residues of DDT and its metabolites found in egg tissues (Snyder et al. 1973). Fledging success rates dropped from 3.53 young per successful nest prior to 1946 to 2.67 during 1946-1967 (Pattee et al. 1985). Despite the ban on DDT that has been in effect in the U.S. since the 1970s, numbers have failed to rebound to former levels in the eastern U.S. (Robbins et al. 1986). This failure to regain their former abundance may be due to the continued use of the pesticide in Central America, where at least part of the species spends the winter. An adult was found dying of acute DDT poisoning as late as 1980 (Prouty et al. 1982). Many prey species consumed are neotropical migrants, and probably continue to be contaminated by DDT during their winters south of the United States. Illegal use of DDT in this country has also been proposed as a possible cause. It is, however, still unclear to what extent DDT or other organochloride pesticides are contributing to the slow rebound of this species. In a study of contaminants in eggs from Connecticut, Maryland, Michigan, Pennsylvania, and Wisconsin, only one egg from Connecticut contained levels of DDE, a break-down product of DDT, above the level hypothesized to cause reproductive failure. The data suggested that egg shell thinning was not a significant problem in these states in 1980, although at least two individual birds had thin-shelled eggs containing high residues. Other contaminants, including other pesticides, PCB, lead and mercury, also showed up at levels below hypothesized impact levels (Pattee et al. 1985). In addition to the hazards of long-lived, bioconcentrating organochlorine pesticides such as DDT, the more widely used and acutely toxic organophosphate pesticides may pose a threat. Two reports of poisoning were made in the 1980s (Rosenfield et al. 1991). So little effort has been put into monitoring this type of poisoning in dead raptors, that it is impossible to assess the magnitude of this threat. HABITAT LOSS: Deforestation has also been cited as a current threat and may become increasingly important. Required habitat (dense forest isolated from human activities or narrow riverine forest corridors) is under pressure for forest product harvest and development (Snyder 1978, Herron 1985, Weir 1987). Habitat loss was cited as the primary threat to raptor populations in a recent survey of U.S. state agencies by the National Wildlife Federation (Rosenfield et al. 1991). Rosenfield et al. (1991), however, concluded that breeding habitat does not appear to be limiting for this species in Wisconsin. They found that hawks often utilized pine plantations for nesting, and in fact may achieve their highest nesting densities in such habitat. Similarly, Wiggers and Kritz (1991) found hawks nesting in rather small stands (an average of 4.1 hectares) of young pines. If this habitat use is common in Wisconsin, it is probably also the case for neighboring Minnesota and Michigan, and suggests that habitat may not be limiting in the Great Lakes region. Also, reports that this species has been moving in to urban/suburban areas also raise questions about the importance of habitat loss (A. Stewart, pers. comm.). Other threats include continued persecution by hunters or irate farmers, and the collection of live birds by falconers. Although bounty hunting was once a major mortality factor for this species, that threat has been curtailed by the legal protection now given all birds of prey. Apart from humans, the greatest enemies are probably other raptors. Great horned owls (Bubo virginianus) are known predators (Terres 1980). Goshawks (Accipiter gentilis) are competitors (Reynolds et al. 1982). Nestlings and eggs are also preyed upon by raccoons (Procyon lotor), crows (CORVUS spp.), and possibly snakes (Schriver 1969, Campbell et al 1990).

Restoration Potential: Given the continued low population levels since the banning of DDT in the United States, the major solution to recovery may require an international end to the use of DDT and related organochlorine pesticides, particularly in Central and South America. If that can be accomplished, this species should be able to return to its former numbers, at least in areas that are still forested. However, it may be that other presently unknown factors are also involved in keeping numbers low.

Preserve Selection and Design Considerations: Although habitat requirements of this species are apparently highly variable and not well-defined, the following conservative guidelines are offered. Blocks of woodlands of a minimum of several hundred hectares (based on measured home range size of 100+ to 700+ hectares) are needed by this species for successful reproduction and foraging; forest tracts of six to eight hectares should be left unthinned around the nests to provide sufficient cover at the nest site (Reynolds et al. 1982, Rosenfield et al. 1991). In addition to protecting known nesting territories, attention also needs to be given to providing additional space into which the population can expand. The degree to which a site can be protected from human intrusion and raccoon predation should also be considered.

Management Requirements: Generally thought to need large tracts of relatively mature forests, particularly during the nesting season. This suggests management options that minimize forest fragmentation. The value or impact of forest edge habitat to this species, however, needs to be defined before management prescriptions can be made. Cooper's hawks reportedly forage in both wooded and open areas (Kingsley and Nicholls 1991). Where riverine forest corridors are used, management to maintain these corridors free of roadways, mining and other long-term disruption is needed (Herron et al. 1985). Additional protection from human disturbance would presumably raise the fledging success rate, since this species usually avoids populated areas when nesting (Snyder 1978). In areas with high raccoon populations, reduction of raccoon access to nests may be needed. Raccoon guards placed on nest trees and precautions taken during nesting studies can greatly decrease raccoon predation (Shriver 1969, Fyfe and Olendorff 1976).

In general, tree cutting in the vicinity of nests should be avoided and known nest sites should be protected from human disturbance during nesting season. A buffer zone of eight-ten hectares with no tree harvest has been recommended (Crocker-Bedford 1990). When managing for the benefit of Cooper's hawks, the practice of thinning stands for commercial or non-commercial purposes should be avoided in order to maintain the preferred density of cover (Reynolds et al. 1982). In the southwestern U.S., Reynolds et al. (1982) recommended the following actions to produce and maintain desired forest conditions: thinning trees in the understory, creating small openings in the forest, and prescribed burning; also deemed important were the provision of abundant snags and large downed logs, woody debris, interspersion of different tree sizes across the landscape, and ample older-aged forest. See Crocker-Bedford and Chaney (1988) for recommendations on management of nesting habitat in northern Arizona, Thomas et al. (1993) for a brief summary of protection and management needs in the Pacific Northwest, and Lefranc and Glinski (1988) for research needs and management recommendations for the southwestern U.S.

Management Research Needs: Mosher et al. (1990) criticizes general bird survey methods, short term trend analysis, and local research projects as inadequate for assessing population status and trends for woodland raptors. He suggests that standardized survey methods and range-wide efforts to define the normal range of reproductive performance, population density, and the factors that affect these parameters are needed. He lists the following research needs: effect of forest maturation on raptor species abundance and composition; impacts of forest management and agricultural practices on raptors; tree age and species composition trends in eastern forests and how and where these trends will likely impact woodland raptors; mechanisms controlling year-to-year fluctuations in reproductive parameters; relationship of reproductive parameters to prey density; and relationship of annual reproductive rate to fall migration counts, if possible. California and Northeastern states should be high priorities for research because of suspected declines or poor population recovery.

Studies determining fledging success are needed along with bioassays for organochlorine residues in eggs and adults. Monitoring levels of organochlorines in adults can be accomplished by assaying blood plasma, which has been shown to correlate quite well with levels in eggs, and hence with egg-shell thinning (Henny and Meeker 1981). Examination of dead hawks for organophosphate pesticide poisoning is needed in light of a few recent reports of Cooper's hawk poisonings (Rosenfield et al. 1991).

Global Protection: Many to very many (13 to >40) occurrences appropriately protected and managed

Comments: Many pairs nest in national parks, wilderness areas, and natural areas in the U.S. and Canada. Several hundred pairs inhabit the 5 million acres of designated wilderness in Idaho alone. Twenty occurrences in Indiana are under protective ownership. However, presence in a national or state forest may offer little protection, depending on which forest management practices are in use. Few states or provinces provide protection under endangered species laws.

Needs: Enforce protection laws. Protect large tracts (> 500 hectares) of dense forests. An international ban on the use of DDT and other bioconcentrating pesticides may be necessary to prevent these chemicals from being transported via the neotropical migratory birds that compose this hawk's diet. Educate the public concerning the value of predatory species in natural ecosystems.

Cooper's hawks occasionally prey on domestic chickens in poultry farms.

Cooper's Hawks prey on wild birds and rodents, which helps keep these populations in check.

Positive Impacts: controls pest population

Stewardship Overview: Populations declined drastically in the eastern half of the continent between the 1940s and the early 1970s. After the ban of DDT in the U.S., populations began to rebound in some areas, but apparently still remain much below pre-DDT era levels throughout much of the region. The population recovered susbstantially in some areas (e.g., Ohio, Wisconsin). The lack of rebound in many areas has led to speculation that DDT is still picked up by migratory birds that winter in Central and South America and compose the major part of the diet. Little data to substantiate this claim exist. Few analyses of reproductive success or of DDT residues in eggs have been conducted, but results do not point to an obvious contaminant problem.

While many suggest that the main solution to recovery appears to be an international ban on the use of DDT and related pesticides, controlling habitat destruction is cited in other references. Research into the reproductive success rates, pesticide residues, prey population levels, habitat characteristics, and competitor populations are needed before a real understanding of how to protect this species is possible. In the meantime, standardized effective survey methods, such as censuses employing taped conspecific calls should be used systematically throughout the species' range to establish population levels and fluctuations. Whenever possible, known nesting sites should be protected from human disturbance and the public should be educated concerning the value predatory species have in maintaining a balance in natural ecosystems.

Comments: Constitutes a superspecies with Accipiter gundlachi and A. bicolor (AOU 1998). See Whaley and White (1994) for information on geographic variation.