Migrating Sharp-shins and Red-tails

     Flap, flap, flap, ssoooaaarr, flap, flap, flap, ssoooaaarr, is the flight pattern of sharp-shinned hawks, including during their journey south every autumn.  Sharp-shinned hawks and red-tailed hawks are both common species and annually pass through southeastern Pennsylvania, as elsewhere in North America, in large numbers to spend winter months farther south. 
     These two species of raptors dominate hawk migrations during October, the sharpies during the first half of the month and the red-tails in the latter half of that same month.  Both kinds on migration cause excitement among bird watchers, whether those people are perched on mountaintop lookouts along Pennsylvania ridges, including Bake Oven Knob, Hawk Mountain Sanctuary or Waggoner's Gap on the Blue Ridge Mountains, or are watching from anyplace else off the mountains.
     Migrating hawks over Pennsylvania have two ways of traveling south in fall; along the southwest-running ridges of the Appalachian Mountains on north or northwest winds, or over farm country and towns when wind is from the east or south, or there is no wind at all.  North and northwest winds get pushed up and over the Appalachians by wind coming from behind, pushing the migrating hawks up as well.  Gravity, however, pulls those birds of prey down.  But with the birds' tacking of wings and tails for lift and flight control, the hawks soar straight ahead for many miles with little effort.     
     Sharpies, red-tails and other kinds of hawks abandon the ridge tops and search for thermals of warmed, rising air over farmland and towns when wind is non-existent, or is light from the south or east.  Those thermals of warm air swirl upward, taking the soaring hawks up with the rising air.  And  when those spiraling hawks reach the zenith of a thermal with little effort, they peel off to the south or southwest.  But as gravity slowly pulls them down, they must seek another thermal and another to stay effortlessly aloft and drifting along for many miles in a day's time.
     Sharp-shins are exciting to see dashing swiftly and often low along the ridge tops, sometimes in almost continuous streams of one or two every few minutes during much of the day in southeastern Pennsylvania during blustery north or northwest winds as the sky clears after a few days of rain or no wind.  About the size of mourning doves, sharpies are buoyant on the wind as they flash by the lookouts, some almost at eye level.  One must watch closely for them because they are visible one second and gone the next. 
     Red-tails, too, migrate south in big numbers under storm-clearing skies and roaring north or northwest winds, which are ideal conditions for them and the sharpies to migrate.  A bit larger than American crows, the majestic red-tailed hawks sail magnificently high in the sky on blustery winds, and often one right after another or in small, ragged groups.  As with the sharp-shins, they are something to see, hence the excitement among bird watchers every October.
     Sharp-shinned hawks prey mostly on small birds in woods and older suburban areas with their tall trees and shrubbery.  These little raptors are built for what they do.  They have short, powerful wings for sweeping this way and that among tree trunks and long tails for split-second steering to catch their swiftly fleeing prey.
     Red-tailed hawks mostly catch rodents, especially gray squirrels, that they dive on from perches high in trees or from circling in the sky.  These daytime raptors are large enough to subdue gray squirrels and one squirrel might feed a red-tail for a couple of days.
     The abundant sharp-shins and red-tails are thrilling to see when they are on migration in October, particularly when they are in some numbers.  And they are most exciting to experience speeding over mountaintops during blustery north or northwest winds.