Nov/Dec 2018For Wildlife Watchers: Cooper’s HawkBy Rob Simbeck
The Cooper’s hawk, named for William Cooper, a naturalist and one of the founders of the New York Academy of Sciences, is widely distributed, from southern Canada to Mexico.
We had gone twenty years without an aerial assault. Yes, everything wanted to eat our chickens, but the attacks were always land-based — foxes, raccoons, possums, stray dogs, even skunks. Once we had critter-proofed our henhouse; they were only vulnerable while roaming the yard, and they had long since learned to scramble and hide in the bushes when there was a hawk nearby.
Not this time. I was in the bedroom when Debby, standing at the kitchen window, yelled, “Hawk on a chicken!” By the time I got there, she was outside, where a Cooper’s hawk had made quick work of Millie, one of our laying hens.
I had once seen a Cooper’s hawk snatch a chickadee out of the air as it flew toward a backyard feeder, but this was on another level, a truly impressive display of the ability to go big, with a victim that outweighed it. Debby sniffled, wiped a tear and cussed the hawk, but when you raise chickens, you lose one now and then, and we knew the hawk had to eat, too.
The American farmer was not always so philosophical about hawks. They were shot on sight in many places, and through the middle of the 20th century, their numbers plummeted. The Cooper’s hawk earned the name “chicken hawk,” although the red-tailed is known for taking chickens as well. In both cases, chickens made up a miniscule portion of their diet, but the reputation lingered. With the introduction of DDT in the 1940s, raptors were in even more trouble, as the chemical accumulated on its way up the food chain and weakened the eggs of hawks and eagles.
A ban on DDT, federal protection for raptors, and changes that returned many small farms to forest land helped strengthen their numbers.
Accipiter cooperii "Cooper’s seizer"
Description: Crow-sized male, blue-gray back, white breast and belly with red streaking. Female larger. Immatures have brown upperparts and white underparts with brown streaking.
Range and Habitat: Southern Canada to Mexico. Winters to Panama. Woodlands.
Reproduction: Elaborate courtship display. Male is primary nest-builder. Female lays three to five eggs.
Viewing Tips: Wooded areas; migrations at Caesar’s Head State Park or Sassafras Mountain.
“Some eastern populations had declined significantly in the mid-1900s,” says Tim Lee, an interpretive ranger for the Mountain Bridge Wilderness Area, “but recent breeding data indicates that breeding populations are recovering.” In fact, estimates suggest there may be 750,000 in the U.S. now.
The Cooper’s hawk, named for William Cooper, a naturalist and one of the founders of the New York Academy of Sciences, is widely distributed, from southern Canada to Mexico. Those in the northern part of its range migrate as far south as Panama, part of eagerly watched migrations across Pennsylvania’s Hawk Mountain, and South Carolina’s Caesars Head State Park, from September through November, along a mountainous route that provides great habitat for roosting and eating as well as thermals and slope updrafts for energy-saving flight.
“The short, rounded wings of the Cooper’s hawk and other accipiters,” says Lee, “increase the surface area, enabling them to capture the updrafts, gain more altitude, and sustain flight for longer without flapping their wings.”
As with many raptors, the female is larger than the male, which is roughly crow-sized. Its size ranges from 15 to 18 inches long, with a wingspan of 28 to 34 inches, and weighs from 10 to 15 ounces. Often mistaken for the smaller, similar-looking sharp-shinned hawk, it is blue-gray on the back, white with red streaking on the breast and belly, with a long tail with gray and black bands and a white band at the tip. It has a large head with red eyes and a black cap (the immature has yellow eyes and a brown cap), with a dark beak, small, strong, and hooked for tearing flesh. Its legs and feet are yellow.
The eyes face forward, meaning they have good depth perception, a must when you’re grabbing as you swoop at high speed. They may watch from a perch, or on the wing, and once they’ve spotted prey, burst from cover and make a grab, with surprise the key ingredient. With mammals, they will often finish the catch and kill on the ground.
Those short, rounded wings and long tail are great for maneuvering through thick understory. Great, but not perfect. A 2002 study of the skeletons of more than three hundred Cooper’s hawks showed that about a quarter had healed-over chest fractures, indicating high-speed crashes weren’t all that uncommon.
Still, they are formidable predators. Their resurgence has impacted the population of the American kestrel, a small raptor that is another favorite meal. They normally kill by constriction, squeezing prey to death. With something as large as a chicken, they might include a well-placed blow from that beak. They primarily eat small to medium-sized birds, including robins, starlings, woodpeckers, doves, jays and quail, but will eat birds as large as pheasants and mammals as large as rabbits. They will rob nests and sometimes eat frogs and lizards.
These are woodland birds, at home in mature forests, wood edges and along tree-lined rivers and streams in open country, but more and more they are found in wooded suburbs or even cities as development eats up woodlands. There they can find doves and pigeons, with backyard feeders serving as a source of protein.
“Once when I was teaching a birding program to a group of schoolchildren,” says Lee, “a Cooper’s hawk turned a bird feeder into a ‘bird feeder.’ We were observing the songbird at the feeder and talking about its size, color, the shape of the bill and other characteristics when it disappeared, leaving only a few floating feathers as evidence that it had been there. Most of the group brought their binoculars down just in time to see the tail of the hawk as it disappeared with its prey into the shrubs. It was a great opportunity to talk with the students about birds of prey.”
Cooper’s hawks are monogamous and theirs is one of the more lyrically beautiful courtship displays. Male and female will fly together, generally on a sunny morning, with the male diving toward her, then flying around her in a wide arc, wings high and flapping slowly, as he displays the underside of his tail feathers. The male may spend two weeks building a nest of sticks, with little help from her. He places it more than halfway up a large tree, usually against the trunk on a horizontal branch. The nest is two or two-and-a-half feet in diameter and a foot high, with a depression eight inches across and four inches wide. They have been known to reuse nests.
She lays three to five pale blue eggs, two by one-and-a-half inches, and incubates them for about a month. The young hatch covered in white down, weighing about an ounce. The male forages for food and brings it to her, sometimes stashing it nearby, and incubates while she eats. They fledge in about a month, returning to the nest to be fed until becoming independent at about two months, with the smaller males maturing a bit earlier. A pair will have one brood per year, but they will produce a second if the first is disrupted. The young have a whistling begging call, while adults have a raspy, crowlike kek-kek-kek call.
The eggs and young are preyed on by crows and other hawks, and sometimes by raccoons and great horned owls, one of the few birds that is a threat to the adult Cooper’s hawk. Red-tailed hawks and goshawks may also attack adults.
Habitat loss is the biggest threat, though, along with the towers, windmills and windows they sometimes collide with. “A common cause of death and injury of Cooper’s hawks,” adds Lee, “is collision with automobiles.”
We are fortunate as wildlife watchers that we’ve overcome the threats that ravaged their numbers half a century ago, and are able to witness more frequently the magnificent strength and agility of these birds, even if, as Debby and I learned, it costs us the occasional chicken.