NETN Species Spotlight - Sharp-shinned Hawk

2018 is Year of the Bird

2018 marks the centennial of the Migratory Bird Treaty Act, considered by many to be the most powerful and important bird-protection law ever passed. In honor of this milestone, National Geographic, the National Audubon Society, the Cornell Lab of Ornithology, and BirdLife International are joining forces with more than 100 other organizations, including the National Park Service, and millions of people around the world to celebrate 2018 as the “Year of the Bird.” As part of this celebration, NETN’s Species Spotlight series will focus on a different bird species each month throughout the year.

A juvenile Sharpie perches on a branch waiting to make it’s move on a feeder full of Chickadees.

Ed Sharron

What is it?

About the size of a Blue-Jay, the Sharp-shinned Hawk is an aerial acrobat. Performing tight-turns and dives, passing through openings that look too small for them to fit, flying with grace and speed that can only leave work-a-day fliers like geese and grebes green with envy, “Sharpie’s” are the smallest of three North American agile hawks known as the accipiters (ah-sip-it-ers).
Widespread, though seldom seen, they make their living in forested areas throughout much of North, Central, and South America. Besides the occasional glimpse you may get of them prowling near your bird feeder, it’s during migration you have the best chance of spotting Sharp-shinned’s in any numbers. Sometimes dozens or even hundreds of these hawks pass over favored migratory routes along coastlines, lake shores, and mountain ridges. During most other times of the year, this relatively secretive bird spends its time in the woods generally staying out-of-sight of human eyes.
Female Sharpie’s are larger than males, true for most birds of prey around the world, though it is particularly pronounced with Sharp -shinneds. Males average only 57% of the mass of females - the biggest disparity between sexes of any North American raptor. One theory for this size difference is that it’s an adaptation that minimizes food competition between sexes, with female birds hunting prey too large for male hawks to tackle. Nestlings feed first on smaller prey caught mainly by the male, switching as they grow to larger female prey.

Fast and Featherous

Like all members of their family they are built for speed and maneuverability, characterized by short wings and a long tail they use like a rudder. This is in contrast to falcons, which have fairly long and pointed wings, and “buteos” (e.g. red-tailed and rough-legged hawks) that have short tails and long, wide wings built for soaring. Like many birds-of-prey, the feather layout, or plumage, of Sharpie’s changes as they age. A juvenile hawk has a mostly dark-brown back, brown vertical streaks down the front of its breast, and yellow eyes. Adults have a greyish-blue back, thick horizontal stripes on its breast, and red eyes. Adding to ID anxiety for beginning birders, Sharpies also have a similar appearance to a slightly larger cousin of theirs: the Coopers Hawk. At a distance, it can be especially hard to distinguish the two birds. A helpful couple of phrases to remember to help with this are: Cooper-Crow-Curved, and Sharpie-Small-Square. The Coopers Hawk is about the size of a Crow, and its tail is curved, or rounded, at the end; whereas the Sharpie is smaller than a Coop, and it’s tail tends to be squared-off at the end.

Bird Feeder Indeed

When you fill your yard bird feeders with lots of seed, you’re likely to attract lots of birds. Attract lots of birds, and you just might attract a roving bird-hawk. In the truest sense of the phrase “bird feeder”,our sunflower-filled receptacles not only feed Chickadees, Blue Jays, Doves and the like each winter, they also feed the bird-eating hawks that take advantage of the large numbers of birds that congregate there each day.

"Sharp" declines

Sharp-shinned Hawk numbers declined significantly in the mid-1900’s, likely from DDT and other pesticides infesting the food chain. They then recovered through the early 1980’s but counts of migrants in the east have since shown significant declines. This may be due at least in part to more birds foregoing migration and spending winters in place.

Accipiters often sit quietly in a tree, and then drop in low for a surprise attack, sometimes chasing their prey through obstacle-laden thickets where they are spectacularly adept at maneuvering. Putting human emotions aside, attracting a feeder hawk is not a bad thing – you may as well view it as a sign your winter bird feeding program is functioning at its highest level. Most hawks that spend the winters in the Northeast need to specialize in catching smaller birds to survive. And not all people get a Sharpie or Coop to visit their feeders, in fact most don’t. If a wintering hawk does set its sights on a bird at your feeder, it will either catch its meal and move on, or miss (which happens quite often) and move on. Either way, your birds will resume with their normal feeding activity in just a couple of minutes - just as if nothing happened.
While it seems to be built into most people’s DNA to sympathize with the smaller birds in this equation, studies have shown that bird-feeder hawks prefer to prey on sick and/or injured birds when possible. The large gatherings of birds at our feeders are otherwise uncommon in the natural world, and can allow for the spread of sickness and disease throughout a flock. By culling the sick birds from the group, feeder hawks help to keep the flock healthy in the long-run.
Songbirds make up the bulk of the Sharp-shinned Hawk’s diet. Birds the size of American Robins or smaller are most often taken - though there have been reports of birds as large as quail, doves, woodpeckers, and even a falcon on at least one occasion. You can thank Sharpie’s for eating some small rodents like mice and voles as well, and they will occasionally snatch up a moth or grasshopper.
The Sharp-shinned’s preference for feeding on songbirds has made the bird unpopular in the public eye over history. This lead many states to withhold legal protection of it until well into the 20th century. Knowing their important role in the ecology of bird populations, instead of begrudging a Sharpie at your feeder, try to recognize the role they play in keeping your birds healthy, and then marvel at the skill and dexterity they exhibit when chasing birds on-the-wing.

For more information

-See a cousin of the Sharpie: a European Sparrowhawk, use its supreme manueverability in this fantastic BBC video.
- For info on NETN’s long-term Breeding Landbird monitoring program see http://go.nps.gov/landbirds.

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