Sharp-shinned hawks, stalkers of the bird world, use all their tricks to gobble smaller prey whole

It is not unusual to see raptors in the city. Red-tailed hawks, peregrine falcons and Cooper’s hawks dominate the scene. But once in a while you might encounter a more elusive species – the sharp-shinned hawk (Accipiter striatus). It is not unheard of to see one at this time of year in the city, most likely near a bird feeder. These blue-jay-sized hawks do not eat seeds, but they are attracted to the birds that visit backyard feeders.

Sharp-shinned hawks – also called sharpies, sharpshins, blue darters or chicken hawks – generally prefer dense forests. The female is about a third larger than the male and therefore can catch larger prey. During the breeding season in the summer, these birds are present throughout the state but are seldom spotted because they nest high in conifers and perch in inconspicuous locations. They do not soar over trees like some other birds.

The spring might be one of the best times to see these small hawks in our area. Ninety percent of a sharp-shinned hawk’s diet is small birds, from the size of a sparrow to the size of a robin. Females might even prey upon a pigeon or dove. Adult hawks need to eat four or five birds each day. For this reason, they follow the warbler migration north in the spring. Mount Auburn Cemetery is a favored resting spot for migrating warblers. Look for them to arrive with winds out of the southwest beginning in April but peaking the first week of May – as a result also one of the best times of the year to spot sharp-shinned hawks. According to Brian Rusnica, president of Eastern Mass Hawk Watch, on May 2, 2021, observers spotted 461 sharp-shinned hawks migrating north over Plum Island.

Sharp-shinned hawks use stealth to hunt. The males, who weigh about 3 ounces (the weight of a deck of cards) are smaller than the females, who weigh about 6 ounces (the weight of a cell phone). A sharpie might sit motionless on a branch waiting to ambush a songbird that happens unsuspectingly by. Or it might surprise its prey by threading its way over or around thickets or other obstacles to ambush it. John James Audubon described the behavior this way in Birds of America:

Many have been the times … when I have seen it plunge headlong among the briary patches of one of our old fields, in defiance of all thorny obstacles, and, passing through, emerge on the other side, bearing off with exultation in its sharp claws a Sparrow or Finch, which it had surprised when at rest.

These hawks squeeze and impale prey with their talons during flight. They carry the prey to a stump or branch where they pluck it before they eat it because, unlike owls, they do not swallow feathers. They eat the rest of the carcass, though, bones and all.

Large numbers of sharp-shinned hawks migrate south from Canadian forests every fall to the Southeastern United States or Central America. They rely on mountain updrafts or thermals to gain elevation and then glide down, conserving as much energy as possible for their long-distance journey. Sharp-shinned hawk numbers are greatest during fall migration because many recently born juveniles boost the population, smaller in the spring because many of these juveniles do not survive. Although sharpies do not migrate in flocks – they are solitary migrants – when weather conditions are good, you can see them in great numbers.

Hawks are one of the most intelligent of birds. In studies of innovative bird-feeding behaviors, crows and falcons topped the list, followed closely by hawks, woodpeckers and herons. The more innovative a species of bird, the larger the forebrain. When scientists have tried to relocate birds to new regions, the most innovative birds were the most successful at surviving or thriving in the new environments. This hawk intelligence may stand them in good stead as climate change alters the hawk’s environment. There is already some evidence that these birds do not migrate as far south as they used to.

Arthur Cleveland Bent in Life Histories of North American Birds of Prey (1937) relays a tale of their intelligence: 

Several times in August and September a pair of sharpshins grew into the habit of using a large meadow as a feeding ground … where woodchucks were often killed by the State patrolmen and left as they lay … [T]he sharpshins became in the habit of appearing at the report of a rifle, playing above the lofty elm trees, nonchalantly watchful of the doings below. What instinct is this that told them man was not there to molest them but the woodchucks, and that later these same spoils would offer up to them a booty?

These hawks were once hunted relentlessly, so making this distinction was perhaps no small feat. Bent tells of a week in September 1920 in Cape May, New Jersey, when hunters shot 1,400 sharpies.

In April or May, the hawk’s breeding season begins. On a major branch about 30 feet above the ground, the hawks build a 2-foot-diameter nest of sticks lined with flakes of bark. The female lays four or five eggs, which hatch in about a month. The male brings food to the female and may sit on the eggs while she eats. Once the chicks hatch, the male continues to bring food, which the female feeds to the chicks. After three or more weeks, the chicks move out onto branches. They begin flying in another week or two. The parents continue to feed the fledglings for several weeks, dropping dead prey nearby. Eventually, the parents, in flight, pass prey from their talons to the youngsters, who grab it as they fly by.

Birds are adapted for flight. Sharp-shinned hawks have a distinctive flap-and-glide flight pattern: flap, flap, flap, glide. Like all birds, they have thin, lightweight bones, a toothless beak (instead of teeth and a jawbone) and fewer bones than mammals. In addition, their forelimbs have evolved into wings, which are helpful for flight but useless for many other tasks. Therefore, birds use their beaks for tasks such as preening their feathers. To reach the feathers in the back of their bodies, sharp-shinned hawks have a flexible neck with 14 neck vertebrae (humans have only seven).

Prey animals have eyes that are far apart on the head, so they can see all around them. Predator species have eyes are closer together in the front of the head (like humans). This allows them to focus on a target. Sharp-shinned hawks have fabulous eyesight and can spot movement from great distances, which is probably why we use the expression to watch something “like a hawk.” They can see eight times better than humans, and they can see four colors (including ultraviolet), instead of the three colors humans can see. Therefore, they pick up details that are impossible for us to see.

Have you taken photos of our urban wild things? Send your images to Cambridge Day, and we may use them as part of a future feature. Include the photographer’s name, date and the general location where the photo was taken as well as any other relevant information.

Jeanine Farley is an educational writer who has lived in the Boston area for more than 30 years. She enjoys taking photos of our urban wild things.

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