2017-10-12 / Nature

Accipiters: The Backyard Songbird's Nightmare

By Charles Avenengo

A merlin falcon looks for prey at Sachuest Point. (Photo by Carmen Rugel) A merlin falcon looks for prey at Sachuest Point. (Photo by Carmen Rugel) The Aquidneck Island backyard typically includes items like lawn furniture, barbecue grills, the occasional pool and frequently bird feeders, where birds of many colors and shapes provide the homeowner with hours of enjoyment.

But this pastoral setting can be savagely upended when a blur streaks by, snatches one of the birds and leaves only feathers drifting to the ground.

The culprits responsible are often raptors of a genus called accipiters. In Rhode Island, there are three types of accipiters: the medium-sized Cooper’s hawk, the larger Northern goshawk, and the smaller, sharp-shinned hawk (called “sharpies”), the nearly identical cousin, and the most numerous of the hawks migrating along the Atlantic seaboard. Their daily numbers sometimes equal the rest of the raptors combined.

As a genus, the accipiters are recognizable by their short, rounded wings and long rudder-like tails. This enables them to maneuver among the trees in wooded areas, their preferred habitat. Their flight pattern consists of several rapid flaps followed by a glide. Worldwide, there are almost 50 species of accipiters. One characteristic of these avian hunters is that females are larger, sometimes by a third, than males.

Cooper's hawk. (File photo) Cooper's hawk. (File photo) Unlike some of the island’s other common raptors that include the widespread red-tailed hawks and the wintering northern harriers, whose preferred quarry is small mammals, accipiters prey primarily on birds. And with a ready supply of food at the bird feeders, it’s no wonder the backyards are their favorite hunting grounds. In addition to the songbirds, accipiters also feast on rabbits, squirrels and the occasional snake.

Falcons, another genus of raptors found locally, also pursue birds. But they hunt in more open spaces, using their sheer speed to overcome slower flying prey.

Bald eagle. (Rey Larsen) Bald eagle. (Rey Larsen) In urban settings like Newport, accipiters tend to ambush their targets by hiding behind obstructions. They employ some innovative techniques. A local property manager at a Bellevue Avenue estate saw a Cooper’s hawk crawling along the ground in an effort to stalk cottontail rabbits. Another account describes a sharp-shinned hawk attempting to secure its meal by extending its talon through a chain-link fence. Goshawks have been seen chasing their victims along the ground.

It is estimated that there are 15 to 20 nesting pairs of Cooper’s hawks on the island. Sharp-shinned hawks are considered rare breeders in Rhode Island and are primarily in the more wooded western and northwestern portions of the state. Goshawks are even rarer here, with only a handful of sightings recorded annually.

Currently, the resident Cooper’s hawk population is augmented by the arrival of additional southward-bound migrating Cooper’s hawks and sharp-shinned hawks.

Migrating raptors follow flyways. They use time-honored routes that involve flying along geographical features to aid in their push south. This includes flying along mountain ridges and coastlines, where they avoid going over water, which they abhor. A good time to witness this phenomenon is in the middle of the day, when the migrating hawks take advantage of air thermals to aid in their journey.

More than 200 hawk watches have been established in North and Central America, where participants record the daily and seasonal tallies of the migration from observation points. The recorded numbers can be staggering. On a good migration day with northerly winds in Rhode Island, an observer might see a few dozen raptors, including a majority of sharp-shinned hawks.

While no formal hawk watches are conducted in Rhode Island, observers had tallied just over 5,000 hawks further west along their migration route, at Lighthouse Point in New Haven, Conn., through last weekend. Approximately 1,500 were sharp-shinned hawks, and about 500 were Cooper’s hawks.

By the time the migrants arrive in Cape May, N.J., the raptors are funneled to a single point before crossing Delaware Bay. Through last weekend, approximately 18,000 raptors had been registered. This included about 6,300 accipiters. In Panama, where hawks from throughout North America funnel through the relatively narrow isthmus before fanning out in South America for the winter, the highest historical autumnal count was recorded in 2015, with an unbelievable 3.2 million hawks recorded.

So, during these final few weeks of suitable temperatures, if birds at your feeder suddenly disappear, it could mean that an accipiter has been lurking nearby.

Raptor species observed on Aquidneck Island:

Turkey vulture
Black vulture
Osprey (nests on Aquidneck Island)
Northern harrier
Sharp-shinned hawk
Cooper’s hawk (nests on Aquidneck Island)
Northern goshawk
Bald eagle
Red-shouldered hawk
Broad-winged hawk
Red-tailed hawk (nests on Aquidneck Island)
Rough-legged hawk
Merlin falcon
Kestrel falcon (very rare nester on Aquidneck Island, formerly more common)
Peregrine falcon (nests on bridges connecting to Aquidneck Island)

Naturalist Charles Avenengo has been chasing Aquidneck Island wildlife for more than 40 years.

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