Cooper’s hawks (Accipiter cooperii) are medium-sized hawks from the genus Accipiter and live across the USA, Canada, and Mexico. These compact hawks are exceptionally fast and agile and have a diverse diet consisting of various mammals, birds, and reptiles. This is a guide to Cooper’s hawk nesting.
Cooper’s hawks build nests in a variety of environments, but they generally prefer coniferous and deciduous woodlands. Nests are built in the fork of a large, mature tree at a height of 8m to 15m or so. The nest itself is typically quite large, measuring up to 45cm (17.7in) deep and 76cm (37.7in) across.
While Cooper’s hawks usually nest in woodland environments, they’re quite flexible, and some strange nests have been observed, such as a nest built in grapevine and one made almost entirely from Spanish moss.
Both the male and female build the nest, but the male tends to do most of the construction work (approximately 70% in one study). Most Cooper’s hawks build new nests yearly, but some are reused each breeding season.
Read on to learn more about the fascinating nesting habits of these well-known American hawks!
Close up of a Cooper's Hawk nest, with chick resting on a branch
Cooper’s hawks mainly nest in coniferous and deciduous woodland, and their preference varies from region to region.
For example, one study revealed that some 70% of nests in Tuscon were built in Eucalyptus trees, and 58% of nests in Massachusetts, 51% in Missouri, and 81% in Illinois were built in pine trees.
In the east, nests were primarily constructed in deciduous trees, including in New York, Maryland, and Florida, where hawks built most nests in oak trees.
Dense woodland and mature trees are preferred, but some nests are built in isolated single trees, e.g., in the middle of a park or golf course.
Cooper’s hawks also prefer dense canopy coverage, with some exceptions, such as when they nest in bare trees in semi-arid environments. Some strange nests have been observed, including one built mostly of Spanish moss and one built in a grapevine.
When Cooper’s hawks nest on a slope, they tend to avoid south-facing slopes, possibly as they become too hot or dry.
Cooper’s hawks also nest in rural, semi-urban, and urban environments, where they’ve become increasingly common in recent years. For example, in the 90s, Cooper’s hawks occupied just 30% of the urban areas surrounding Chicago, but this has increased to over 70% in recent years.
Cooper's Hawk chicks inside the nest in the woodlands
Cooper’s hawk nests form large platforms that measure a maximum of 45cm (17.7in) deep and 76cm (37.7in) across. The nest is constructed from twigs and branches and has a cup-shaped depression.
Some nests are lined with green foliage or bark, which is usually transported to the nest and placed by the female toward the end of the construction process.
The resulting structure is extensive, especially when built in a large deciduous tree. Nests in conifer trees are smaller, probably because there’s less room to build a larger nest.
Close up of an adult Cooper's Hawk, perched on a tree branch
Cooper’s hawk nests are large given the size of the bird, measuring around 61 to 76cm (24 to 30in) across and 15 to 45cm (5.9 to 17.7in) deep. Nests in coniferous trees are generally smaller, measuring approximately 15 to 20cm (5.9 to 7.9in).
Nests are also bigger in the north and east of their bird’s range, probably because eastern Cooper’s hawks are larger than western Cooper’s hawks and therefore require larger nests. However, nest size is flexible and depends on available species of trees.
Cooper’s hawks usually build their nests in late winter or early spring, from late February to March. Depending on the region, female Cooper’s hawks typically lay eggs from March until May.
There are some reports of Cooper’s hawks building nests in the fall or the non-breeding season. Most of the time, however, nest building starts two weeks before copulation.
Nesting Cooper's Hawk feeding chicks in the nest
Cooper’s hawks select a valid nesting site before the spring breeding season. Then, the male will begin stockpiling material near the nest and take care of most of the construction process.
The female often ‘inspects’ the nest throughout the build process, which takes around two weeks. In addition, the female occasionally assists construction, particularly towards the end of the construction process when it’s time to line the cup with bark.
Nests are built from twigs and branches, with the occasional smattering of loose foliage thrown in for good measure.
Baby Cooper’s hawks grow rapidly and fledge when they’re 27 to 32 days old. The young hawks remain close to the nest for two to three weeks and return to roost and feed.
The young hawks become entirely independent from their parents after around two months. This is relatively quick for a hawk - some young hawks remain dependent on their parents for much longer.
Recently fledged young Cooper's Hawk
Cooper’s hawks have a single brood of 2 to 4 chicks, assuming that all the eggs hatch. Around 74% of the eggs hatch, and 50% to 70% of nests succeed. If a nest fails, all eggs are lost.
One study found that 86% of nests produced at least one fledgling, but most successful nests produce 1 to 3 fledglings, with very few producing 4 or 5.
Cooper’s hawk eggs measure around 2 inches long and 1.5 inches wide and are a pale blue or blue-white color, with small semi-transparent pale brown speckles. Some eggs are a dirty white and lack any other markings.
Close up of a Cooper's Hawk
Cooper’s hawks generally return to the same breeding grounds yearly after migration but usually build a new nest.
However, a few studies have found Cooper’s hawks reusing nests, including one nest that a pair of hawks reused for four consecutive years.
here’s little evidence to suggest when and why a pair of Cooper’s hawks choose to reuse a nest rather than build a new one. Perhaps the strongest, most stable nests in favored environments are reused.
Cooper’s hawks lay their eggs between mid-March to late May, rarely later.
In Florida, Arizona, California, New York, and Ohio, most Cooper’s hawks lay their eggs in late April. In Ontario, Wisconsin, and Oregon, egg-laying usually occurs in early May. Younger immature females generally lay later than females.
Close up of a juvenile Cooper's Hawk
While Cooper’s hawks prefer dense, wild woodland typically isolated from humans, their presence in semi-urban and urban areas is increasing.
Cooper’s hawks are not uncommon in backyards across the US and are not always savored by homeowners due to their tendency to hunt and kill small birds.
A few days after their chicks hatch, adult Cooper’s hawks don’t necessarily attend the nest 24/7. Instead, both parents may hunt simultaneously, leaving the chicks inside the nest for short periods.
The male hunts continuously throughout this period, and the female will only join if his food deliveries are insufficient.
Studies show that human disruption of the nest sometimes results in temporary abandonment, which causes a tiny percentage of nest failures (1.2% in the study).
Cooper’s hawks don’t nest in cavities and won’t use nesting boxes. Instead, they may use nesting platforms provided for other birds of prey.
Cooper’s hawks roost high up in deciduous and coniferous trees. There’s no evidence to suggest that they roost communally.
Cooper’s hawks prefer deciduous and coniferous trees, such as pines, oaks, firs, beeches, and spruces.
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