Cooper’s hawks are medium-sized hawks found throughout North America. They are adept hunters that prey on birds and small mammals. Cooper’s hawks build nests and lay eggs during the springtime each year. The exact timing of nesting and egg laying depends on the local climate and conditions.
What are Cooper’s Hawks?
Cooper’s hawks (Accipiter cooperii) are medium-sized hawks that are native to North America. They are a member of the Accipitridae family of diurnal raptors. Some key facts about Cooper’s hawks:
– They are about 15-20 inches in length with a wingspan around 30 inches. Males are typically smaller than females.
– Adults have blue-gray upperparts, reddish barring on the chest, and red eyes. The underparts can range from reddish to white.
– Cooper’s hawks are found throughout the United States, southern Canada, and Mexico.
– They inhabit forested areas including deciduous, mixed, and coniferous woodlands. Also found in urban parks and wooded suburbs.
– A skilled predator that captures prey on the wing or with swift maneuvers through dense cover. They prey primarily on birds like doves, woodpeckers, and songbirds but also eat small mammals, reptiles, and amphibians.
– Nests are built in the crotch or fork of deciduous or coniferous trees. The nests are typically 25-50 feet above the ground.
Breeding and Nesting
Cooper’s hawks nest in the springtime so that young hatch out when prey is abundant. Courtship begins in late winter or early spring. The male performs aerial displays to impress the female. Once a pair bond has formed, they build a nest together. The nest is constructed of twigs and lined with bark strips and foliage.
Egg laying typically begins in late March or April but can range from mid-February to late May depending on location. The timing ensures young fledge in the summer when food is plentiful.
Clutch Size
The female Cooper’s hawk typically lays between 3-6 eggs. The average clutch size is around 4-5 eggs. The eggs are laid in intervals of 2-3 days between each one. The female does all of the incubating while the male provides food.
Incubation Period
The eggs are incubated for 30-36 days before hatching. The female stays on the nest constantly during incubation, only leaving for brief periods to eat prey brought by the male. She develops a brood patch with no feathers to provide warmth for the eggs. Incubation keeps the eggs between 85-92°F until hatching.
Nesting Habits and Locations
Cooper’s hawks are adaptable nesters, building in a variety of tree species and sites. Here are some details on their nesting habits and favored locations:
Tree Type
Cooper’s hawks typically nest in deciduous trees but will also use conifers. Some common nest trees include oaks, maples, cottonwoods, willows, and pines. The tree provides a sturdy crotch or fork for nest placement.
Nest Height
Nests are usually 25-50 feet above ground but can be as low as 10 feet or over 90 feet high. Higher nests may provide more protection from predators. Lower nests likely offer easier access and escape routes.
Nest Sites
Cooper’s hawks favor sites that provide protection overhead and around the nest. Nests are often located near the trunk, under large horizontal limbs, or under canopy cover. Having dense foliage above helps conceal the nest.
Habitat Types
In natural settings, Cooper’s hawks nest in mature deciduous, coniferous, or mixed forests. They also readily nest in parks, quiet suburbs, and other urban green spaces with tall trees.
Range and Distribution
Cooper’s hawks breed throughout their range in North America. Here is an overview of where they nest and lay eggs based on region:
Canada
In Canada, breeding occurs from British Columbia east to Nova Scotia. Nesting takes place throughout the boreal forests of the Taiga Shield ecozone. Cooper’s hawks inhabit forests across Canada’s various climate zones.
United States
Cooper’s hawks nest throughout the lower 48 states. They breed in forests across a variety of biomes including eastern temperate, subtropics, west coast marine, and highlands. Their breeding range spans from Maine to Florida to California.
Mexico
The breeding range extends south throughout much of Mexico. Cooper’s hawks nest in forested mountains and tropical areas from Sonora and Chihuahua down through Jalisco and Veracruz.
Latitude Range
Overall, Cooper’s hawks breed between 25°N latitude in Mexico up to 60°N latitude in Alaska and Canada. Their extensive latitudinal range allows breeding in varied climates and habitats.
Regional Nesting and Egg Laying Timeframes
While the nesting season occurs in spring across North America, the exact timing varies by region according to local conditions. Here are rough timeframes by region:
Southern Range
In the southernmost regions like Florida and Mexico, nesting can begin as early as February or March. Egg-laying typically occurs from mid-March through April.
Central Range
From the mid and south-central states like Texas, Colorado, and Kansas, egg laying normally takes place from early April to early May.
Northern Range
In the northern parts of the range like Alaska, Canada, and Maine, the majority of egg laying happens from mid-May through June. The later start ensures chicks hatch when prey is abundant.
West Coast
In coastal areas like California and the Pacific Northwest, the timeframe falls between that of the central and northern inland range. Laying often occurs April through May.
Mountain Ranges
At higher elevations in mountain ranges, nesting tends to occur a few weeks later than surrounding lower elevations. For example, in the Appalachians of Tennessee, egg-laying may take place in April or May while lower elevations see March and April.
Factors Influencing Nesting and Egg Laying Timing
Several factors influence the timing of breeding, nesting, and egg laying in Cooper’s hawks:
Weather and Temperature
Warmer temperatures allow for earlier nesting and egg laying. Cooler spring temperatures delay the breeding season until conditions improve. Abundant spring rain provides foliage for nest building.
Day Length
Increasing day length in spring stimulates breeding behavior and hormones. Shorter days earlier in the year prevent nesting.
Prey Availability
Adequate prey is needed to feed incubating/brooding females and nestlings. Nesting coincides with higher prey populations.
Age
Older, more experienced breeders may nest earlier than younger first-time breeders. Nesting skills improve with age and experience.
Elevation
Higher elevations have cooler temperatures that delay nesting. Lower elevations tend to allow earlier breeding and egg laying.
Latitude
More southern latitudes provide warmer weather and earlier springs. Northern areas have later springs that hold back nesting until temperatures rise.
Significance of Spring Nesting
The spring nesting and egg laying timing is significant for Cooper’s hawk breeding success in a few key ways:
Fledged Young in Summer
Spring nesting provides timing for eggs to hatch and nestlings to fledge as summer begins. The summer season offers plentiful food sources like fledgling birds for the young hawks.
Mate Synchronization
Courtship displays help synchronize the reproductive conditions of the male and female. This coordination leads to successful breeding.
Weather Conditions
Spring weather with longer days, more sunlight, and warmer temperatures aids in egg development and chick rearing. The higher energy demands are met by seasonal conditions.
Prey Availability
Prey is scarce during winter months. Spring increases populations of birds, mammals, and other prey as ecosystems become more productive. More food availability allows for successful breeding.
Territorial Establishment
Spring nesting allows pairs to establish breeding territories that provide food and nesting resources. Securing high-quality areas helps increase chances of reproductive success.
Comparison to Other Hawk Species
The spring nesting of Cooper’s hawks lines up closely with that of its fellow North American Accipiter hawks – the sharp-shinned hawk and the northern goshawk. Some key comparisons:
Sharp-Shinned Hawk
– Smaller relative of the Cooper’s hawk at 10-14 inches long.
– Very similar breeding ecology and behaviors.
– Nesting begins late March to early May depending on latitude.
– Lays 3-8 eggs (average 4-5) in April/May.
Northern Goshawk
– Larger accipiter at 20-26 inches long.
– Nesting starts mid-April to early June.
– Lays 2-4 eggs in May or June.
– Occurs further north than other two accipiters.
– More likely to be in higher elevation forests.
So while exact timing varies slightly based on size and range, the Accipiter hawks all begin breeding and egg laying in the spring months between March and June throughout their North American ranges.
Comparison to Other Bird Species
Beyond other hawks, the spring nesting of Cooper’s hawks parallels that of numerous songbirds that also breed during spring and summer:
Mourning Doves
– Small game bird preyed upon by Cooper’s hawks.
– Nest from March to September with peak in May-June.
– Lay 2 eggs that incubate for 14 days.
American Robins
– Common songbird prey for Cooper’s hawks.
– Nest from April to July with peak in May/June.
– Lay 3-5 eggs that incubate 11-14 days.
Chickadees
– Small songbirds taken by hawks.
– Cavity nesters nesting April to July, peaking in May.
– Lay 5-8 eggs over 1-2 week periods that incubate for 12-13 days.
The spring nesting and egg laying of these avian prey species provides abundant food for hawk nestlings once they hatch in early summer just as the songbirds are fledging their own young.
Egg Laying Dates Over Time
Some research using long-term nesting records has revealed shifts in laying dates for Cooper’s hawks over recent decades. These shifts provide insights into how breeding times can change in response to climate and other environmental factors:
New York State
A 50-year dataset of egg dates for upstate New York Cooper’s hawks showed:
– Average first egg date advanced by over 5 days from 1959 to 2008.
– Shift correlated with warmer spring temperatures and earlier snowmelt over the same period.
Wisconsin
A study using nesting data from 1940-2005 found:
– Mean first egg date became earlier by 0.68 days per decade.
– Temperature and precipitation also changed over the study period.
California
Examining records from 1981-2000 showed:
– Median first egg date shifted earlier by 1 day per decade.
– Changes likely related to prey availability and weather factors like rainfall.
Arizona
In a desert study area, the first egg date got 1.67 days earlier on average with each passing decade from 1971 to 2005.
These cases show how Cooper’s hawk breeding times can shift in response to climate and environmental changes over decades. Their flexibility helps them adjust to changing conditions within their widespread range.
Conclusion
In conclusion, Cooper’s hawks breed during the spring months across their range in North America. Nest building and egg laying occurs generally from March through June, varying by latitude and regional climate conditions. Their spring nesting ensures young hatch at a time of abundant food resources. The exact timing of breeding and laying is influenced by factors like temperature, prey availability, and age. Comparisons to other raptors and songbirds show Cooper’s hawks synchronize nesting with other species that provide food sources. Research demonstrates how breeding times can shift over decades in response to environmental changes. The ability to adjust nesting timeframes aids Cooper’s hawks across the continent. Their continued success reflects adaptations that allow flexibility in the seasonality of their breeding biology and behavior.