Birds : Equinox approaches
The tropical storm/ hurricane season has so far turned out to be a dud for birds. Fortunately for Martha's Vineyard there was little excitement in harbors and no property damage after a couple of near misses. With the recent change in the wind direction the fall migration is rocking and rolling. Birders are out in force and birds of all persuasions are on the move. For birders, every morning holds potential and the thrill of the unexpected during this season.
The promise of new birds is always right in front of you, in the next bush, around the next bend in the road, or at a favorite nearby location. Many mornings feature strange or unfamiliar bird chip notes emanating from familiar trees and bushes. Or as one goes about one's business, chip notes are detected from somewhere nearby or overhead, making concentration on anything else difficult. This is a wonderful problem to have, and it only occurs for a few very special weeks in the fall.
Birds that had been waiting to depart the northern woodlands were waiting for high pressure and a northwest wind. These birds had been feeding and resting, biding their time. Their highly evolved migratory impulses, honed through countless generations, are running on high alert.
The temperature has been dropping, the days are getting shorter more and more quickly, and their food supply was starting to dwindle. Yet, they had to wait for the right weather to depart. The clearing frontal system with accompanying northwest winds that occurred on Sunday and Monday nights was what they had been waiting for.
From what are taxonomically considered to be the most primitive to the most advanced, birds are moving, and virtually any bird could actually appear during this season. Both falcons, speedy long-winged aerial hunters and accipiters, relatively short-winged, long-tailed aerial ambush specialists, are migrating, and can often be seen with little effort. The best way to see these birds is to visit the western tip of Martha's Vineyard, the Gay Head Cliffs or either north or south facing shorelines, on days with westerly winds, after 10 am in the morning.
In the past week all three regularly occurring falcons, American kestrel, merlin, and peregrine have been seen often in several locations. The falcon migration is just beginning. The falcons are not alone as birds in the genus accipiter. Sharp-shinned and Cooper's hawks are also becoming more common, with peak migratory numbers in the early part of October.
Other raptors on the move include ospreys, northern harriers, and the occasional hawk in the genus Buteo. The Buteos dislike crossing water, so they seldom venture to the Vineyard, with the exception of the locally breeding red-tailed hawks.
Most impressive and hard to miss in places where they are staging and feasting on bayberries are massive flocks of tree swallows. These birds are superb flyers and during the fall migration they gather en masse, often in uncountable numbers. If they weren't so small and didn't make such charming little call notes they might scare the heck out of people, with visions of "The Birds," Alfred Hitchcock's 1963 horror flick, coming to mind.
Tree swallows can be seen almost continually at altitude by sharp observers, whereas the massive concentrations down low seem to occur in only a few notable spots like Cape Poge and Wasque in Edgartown, anywhere along the south shore, particularly at the east or west corners of the great ponds, Squibnocket in Chilmark, and along Moshup Trail in Aquinnah. While in pursuit of scaly sea creatures, Derby shore fishermen see large numbers of tree swallows (as well as monarch butterflies).
Listening to nocturnal migrants as they stream by overhead, unseen, uttering subtle but distinct chip or contact notes, produces a feeling like no other. It is completely and totally remarkable, the phenomenon of bird migration. To realize that in a beautiful September night, thousands and thousands, even millions of small insectivorous birds of a staggering variety - thrushes, vireos, wood warblers, orioles - are engaging in a spectacular migration.
Imagine weighing far less than an ounce and being able to summer in Canada and winter in the Neotropics. Bird brains are far more complex and evolved than any terrestrial being can fathom.
So, standing out on a lawn, ears skyward, listening to the steady and frequent, but distant, sounds coming out of the night sky, one cannot fail to be awed by this fantastic event going on right over one's head. The distinctive calls that are fairly easy to recognize once one is familiar with them are not the majority of what is emanating from the night sky.
There are all the unknown calls that have to be deciphered. Birds that migrate at night, which is most of the small landbirds in this part of the world, make different sounds while flying in the dark than they do in the day. This is most inconvenient for birders attempting to figure out what is going on in the night sky.
Until next time - keep your eyes to the sky.