Cooper’s Hawk

The Cooper’s Hawk is a secretive, inconspicuous species, particularly during the breeding season and even in areas where it is a common nester. Female Cooper’s Hawks are about one-third larger than males and this species shows among the greatest reversed size dimorphism of any of the world’s hawks. It breeds from southern Canada, is a year round resident of the majority of the lower 48 US and winters in southern US, Mexico and small areas of Central America.

Adult Male (spring/summer)

Dark gray cap, lighter gray auricular and pale gray nape. Red eye. Back, rump, uppertail coverts and wings steely blue-gray. Tail is long, narrow, rounded and steely blue-gray with dark bands. Breast and flanks have fine reddish barring and undertail coverts are white.

Adult Female (spring/summer)

Similar to male but larger.

Juvenile

Immature individuals are brown backed with thin dark brown streaking on their breasts. They have dark brown bands on their tail and a yellowish iris.

General:

Medium-size accipiter with relatively large head and long tail. Holds wings straight when soaring. Length: 37-39cm. Wing: 69-90. Weight: 220-410grams.

Behaviour:

Cooper’s Hawks use surprise and short bursts of speed to catch a variety of prey, mainly medium-sized birds and mammals such as doves, jays, robins chipmunks and other rodents. They hunt from perches by staying hidden in large trees and using their short wings to sneak through thick wooded areas. They can also be seen soaring during migration like most other hawks.

Habitat:

Cooper’s Hawks are forest and woodland birds but can also be found in most habitats throughout their range, including urban and suburban settings.

Information:

The Coopers Hawk may have been the most ubiquitous hawk in the forests of the New World for early settlers thus becoming known as the “Chicken Hawk”. The bird’s official name honours zoologist William Cooper, who lived from 1798 to 1864 and first described this exclusively New World species.
The Coopers Hawk does not tolerate smaller, competitive Sharp-shinned Hawk within same woodland. Nest building is done by the male while the female watches, occasionally chattering her approval or adding to the nest. The male also supplies nearly all food to females and young. Placed on horizontal branches against the trunk of a conifer, or in a crotch of a dense deciduous tree, the nest is a little over 2ft wide and quite flat topped 10-60ft high. The bowl, which holds 3-6 bluish eggs, is lined with flakes of bark.

Similar species:

Sharp-shinned Hawk

Conservation Status:

Listed as Least Concern. Populations appear to be stable.

Capture Rates

The Cooper’s Hawk is a short distance migrant, moving south in the winter. It is an infrequent capture in our songbird nets and can easily escape due to its size. Most birds banded are hatch year birds in August through October corresponding to juvenile dispersal and the start of migration.

Molt Summary:

Complex Basic Strategy (CBS): One inserted molt in the first cycle and no inserted molts in the definitive cycles.

Preformative molt (PF): Previously referred to as “first prebasic molt” but now considered a unique inserted molt within the first cycle.

CBS. PF absent-limited, PB2 (Second Prebasic Molt) incomplete-complete (Apr-Aug in non-breeding SYs), DPB (Definitive Prebasic Molt) incomplete-complete (May-Oct in breeding AHYs).

DPBs can be incomplete, scattered wing covs and rump feathers, 1-6 ss and (rarely) 1-2 rects retained. females average more feathers replaced than males.

Measurements:

F: Wing chord: >239mm; Tail >200mm
M: Wing chord: <239mm; Tail <200mm

Upperparts mostly to entirely brown, the feathers with distinct rufous to buffy fringing, sometimes with scattered bluish feathers (Feb-Oct).

Underparts and underwing coverts with brownish or rufous streaks. Rectrices narrow and rounded, r2-r5 with 4-6 distinct and narrow brown bands. Lesser coverts and rump feathers with distinct white spots.

Iris variable ranging from dull yellow/orangish yellow to bluish.

This second year (SY) female in April is showing a yellow iris diagnostic of HY/SY birds.

The wing of the bird above is showing feathers with distinct rufous to buffy fringing, with scattered bluish feathers.

The tail of the same bird showing the number of dusky bars in the tail which is greater and more distinct in HY/SY than AHY/ASY birds.