Migrant Raptors in August

     The migrations of southbound, diurnal raptors (hawks and eagles) begins in August each year.  And ospreys, bald eagles, broad-winged hawks, sharp-shinned hawks, red-tailed hawks and American kestrels are the most common migrants during August, the first month of southbound raptor passages.  We know that because people staff rocky look-outs on mountain tops along some of the Appalachian Mountains in Pennsylvania, West Virginia and other states the Appalachians pass through.  A few of those watches on mountains in Pennsylvania that come to mind include Hawk Mountain Sanctuary, Bake Oven, Waggoner's Gap and Second Mountain.
     People staff those lookouts from the beginning of August through December every year to learn what raptors are coming through this area during their fall migrations, how many there are, whether their populations are increasing or decreasing, and what are their flight patterns in different weather and wind direction circumstances.
     Generally, when the wind comes from the northwest or north, it pushes up and over the southwest running Appalachians, pushing the hawks and eagles up with it.  Gravity wants to pull the raptors down, so by setting their wings just right, the raptors can soar ahead for many miles with little effort.       But when wind comes from the other directions, the raptors don't get the lift they need from the mountains, so they scatter off them and across flat land.  Then those hawks and eagles can be spotted most any place.
     Ospreys and bald eagles are big and majestic on the wing, causing excitement among many people, as they pass anywhere over Pennsylvania on their way south for the winter.  And both of those species can be spotted around larger bodies of water as they watch for bigger fish to catch and eat before going farther south.  Their migrations, as species, continue during September and October. 
     Broad-winged hawks are unique among raptors in the eastern United States in that they migrate south in flocks, often large gatherings of hundreds.  Broadies are exciting to see flying and soaring out of the woods they spent the night in and seeking thermals, which are columns of sun-warmed air rising up into the sky.  When broad-wings find a thermal, they enter it and it spirals them high into the sky, again with little effort, until they are almost out of sight.  When they have gone as high as they can, the broadies peel out of the thermal, by the dozens, scores or hundreds, and head southwest in long lines or sheets of themselves.  But gravity pulls them down, bit by bit, and so they are obliged to find another thermal and another, all day, every day of their migration south to Central and northern South America where they spend the northern winter.  Broad-wings migrate out of the eastern United States during August and September, with a peak of exodus around September 20th.  By the end of September, they have all left this part of North America.  
     Broad-wings raise young in eastern North American forests and feed them frogs, mice, small birds, larger insects and so on.  Because they ingest so many small, cold-blooded critters that aren't available in winter, broadies must winter in the tropics to get food.  In fact, birds in general, migrate not to escape winter's cold, but to find reliable sources of food through that harshest of seasons.         
     The small, stream-lined sharp-shinned hawks, the large, soaring red-tailed hawks and those diminutive falcons, the American kestrels, all migrate through Pennsylvania in good numbers during August and September.  Sharp-shins also pass through here during October and red-tails during November and into December.  Sharpies prey mostly on small birds, while red-tails and kestrels mostly catch mice, and other rodents in the case of the red-tails.     
     Red-tails are also stately on the wing, and exciting when many are seen migrating south, one after another, in almost a steady stream.  This species is especially appealing on migration in the chilling, thrilling winds of October, November and into December. 
    Some kestrels pass through here and continue farther south.  But others spend the winter here, mostly catching mice and small birds in fields and along roadsides and hedgerows.
     This fall, or succeeding ones, watch for migrating diurnal raptors, starting in August.  They are handsome, and thrilling riding the winds or thermals to their wintering grounds.