Raptors, the Sky Masters

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But flapping one’s wings is costly in terms of energy, so most raptors have mastered easier ways to fly: soaring and gliding. The ability to soar — to gain altitude without flapping — is a hallmark of raptors, shared by only a few other birds such as ravens, gulls and albatrosses. The key is the birds’ light weight compared to the surface area of wing and tail.

Raptors soar by catching the winds pushed upward by mountains, trees or buildings, or by riding invisible columns of rising warm air called thermals. Deflected winds buffeted upward along extended ridgelines such as the Appalachian Mountains can carry migrating hawks hundreds of miles, reducing the energy they need by 50 percent to 75 percent. Thermals serve as elevators: jumping-off (or, rather, jumping-up) places for raptors to gain altitude quickly. Once aloft, a raptor can stay in the thermal, riding it in spirals, or leave the bubble of buoyancy to fly or glide. Most raptors use a combination of soaring, gliding and flapping.

Kestrels, falcons, osprey and some hawks also can hover, a trick generally confined to smaller birds. And a handful of hawks, including the red-tailed, can fly in place without flapping: a technique called kiting. It takes binoculars to detect the subtle flicks of wing and tail that suspend the seemingly motionless bird in air.

FAMILY PORTRAITS

Here are more detailed looks at some of the major groups of North American birds of prey.

Raptor Royalty: Eagles. Few of the world’s birds are as emblematic as North America’s two eagle species, the instantly recognizable bald eagle — our nation’s symbol — and the majestic golden eagle, the all-powerful “Thunderbird” revered by many Native American tribes.

Size defines an eagle: At 9 to 10 pounds and 2½ feet long, with wingspans up to 7 feet, both species clearly qualify. Golden eagles live primarily in western North America, from Alaska to Mexico, hunting mostly from the air for small mammals and birds. Bald eagles, which range across the entire continent above Mexico except for the Far North, spend most of their time perched near large bodies of water watching for unwary fish or signs of carrion.

Like most raptors, both golden and bald eagles mate for life and build their nest to last, adding new materials atop the old each year. New nests typically measure 5 to 6 feet wide and deep. But over generations, the nests can become massive: one Ohio bald eagle nest, occupied for 35 years, weighed 2 tons when its supporting tree collapsed; another in Florida measured 9½ feet across and 20 feet deep.

Beautiful Bounty: Buteos. Buteos are broad-winged, short-tailed soaring hawks. Most (such as rough-legged, ferruginous and Swainson’s) inhabit open country. Some (such as red-shouldered and broad-winged hawks) favor forests. Gray, Harris’s and zone-tailed hawks occupy only the deep Southwest and points below the border. Others occupy much larger ranges.

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