Immature bald eagles do not acquire the typical white head and tail until they are four to five years of age.
New Jersey Endangered and Threatened Species Field Guide
Species Group: Bird
State: Special Concern
The Cooper’s hawk is one of the three species of accipiters that are found in North America. They are woodland hawks that prey chiefly on birds. They are one of the most agile forest-nesting raptors. They are able to quickly maneuver through dense cover while chasing prey. They are about the size of a crow. Cooper’s hawks have short, rounded wings and a long, narrow tail. When in flight the head extends beyond the wrist. This makes it appear as it has a large head. In flight, the silhouette of a Cooper’s hawk appears cross-shaped. The similarly plumaged Sharp-shinned hawk looks small-headed and T-shaped. Cooper’s hawks have a slightly rounded tail with a white edge. The outermost retrices or tail feathers are slightly shorter than the others. The Cooper’s hawk has stiff powerful wing beats.
The adult Cooper’s hawk has a dark cap, blue-gray back, and rusty, barred feathers on its breast and belly. The juvenile’s overall color is brown with rufous (reddish brown) feather edges. It has sparse white spotting and the belly and breast are light colored with brown vertical streaks. Juveniles molt into adult plumage during their second year. Eye color changes from yellow-green in immature birds to dark orange or red in adults. Females are significantly larger than males. The call of the Cooper’s hawk, which is often given during the breeding season, is a loud and nasal “cak-cak-cak.”
Distribution and Habitat
The Cooper’s hawk breeds in southern Canada, the contiguous United States, and northern Mexico. It winters in the U.S., Mexico, and sometimes south into Central America.
In New Jersey, the Cooper’s hawk inhabits a variety of forested habitats. They nest in deciduous, coniferous, and mixed riparian or wetland forests. Cooper’s hawk nest sites are often located within forests that provide a closed canopy and a moderate to heavy shrub cover. Forests usually contain trees that are more than 30 years old.
Nesting territories often contain forest edges and small openings along streams or roads. These areas may be used for hunting. During the 1970’s breeding was only documented in large contiguous forests. Pairs are nesting in smaller and more fragmented forested areas as the population has increased. Many of these areas are within agricultural, suburban, or urban landscapes. They may tolerate a limited amount of human disturbance and habitat fragmentation. Cooper’s hawks occur year-round in New Jersey. They use many of the same habitats in winter as during the breeding season. During the winter their habitat requirements are less strict because of the limited numbers of available prey. Cooper’s hawks forage within a variety of forest types as well as woodland edges. It is common sight in the winter to see a Cooper’s hawk in residential areas where they hunt songbirds and doves at bird feeders. Coniferous trees and forests provide protection from harsh weather is favored for roosting in the winter.
The diet of the Cooper’s hawk is largely comprised of small to medium-sized birds. Some common prey species include thrushes, jays, woodpeckers, blackbirds, doves, sparrows, and European starlings (Sturnus vulgaris). These hawks are known to pursue any bird that is within the acceptable size range. Since females are significantly larger than male, they can take larger prey. Small mammals, reptiles, and amphibians are prey, but to a lesser extent.
These hawks are specially adapted to fly in forests after prey. Their short rounded wings and long tails allow them to maneuver through dense vegetation. Their long legs and toes along them to grab prey in flight.
In New Jersey, Cooper’s hawks breed from April through July. Pairs mate for life. They usually return to the same nest site from year to year. Their breeding territory may contain several nests that have been used from different years. From late March to late April, bonded pairs perform courtship flights over their territory. Males are known to perform courtship displays where they exhibit slow wing flaps and tail pumping to strengthen pair bonds.
They build stick nests usually in the fork of a main branch in a large deciduous tree. Old hawk or crow nests are sometimes used as bases for new nests. Nests are lined with pieces of bark and twigs by the male. Nearby a stump, log, old nest or large branch is used as a “plucking post” where they consume their prey.
Females lay between 4 and 5 eggs. They incubate then for 32 to 36 days. The young hatch nearly synchronously. This means that the female started to incubate when the complete clutch of eggs has been laid. When the young hatch they are downy and need close parental care. The young fledge or fly for the first time in 3 to 4 weeks. The male does the majority of hunting from incubation to the early nestling stage.
Current Threats, Status, and Conservation
Many species of raptors were shot during migration and in the breeding season until the mid-1930s. They were shot in large numbers because of suspected poultry and game bird predation. Amazingly, the Cooper's hawk remained fairly common in New Jersey.
In the 1950s habitat loss caused population declines. The pesticideDDT also reduced reproduction and contributed to declines in the population. Declines were observed from the 1950s to 1970s. The Cooper’s hawk was listed as an endangered species in New Jersey in 1974. Populations began to recover after the ban on DDT in 1972 and many areas became reforested through natural succession. Recent surveys have shown a substantial increase in the breeding population of Cooper’s hawks in New Jersey. In 1999, the status of the Cooper's hawk was reclassified from endangered to threatened in New Jersey. In 2012, its status was reclassified to special concern. The loss of large, contiguous forests remains a threat to this species and warrants the continued protection of Cooper’s hawk nesting habitats.
Text derived from the book, Endangered and Threatened Wildlife of New Jersey. 2003. Originally written by Sherry Liguori. Originally edited by B.E. Beans & L. Niles. Edited and updated in 2012 by Michael J. Davenport.
Species: A. cooperii
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