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Birds:
Fall migration weather patterns
August 4, 2005
By
E. Vernon Laux
Shore birds on the move. A flock of semipalmated sandpipers reacts to a northern harrier's approach. |
July went by so fast that that it seems impossible it is already August. My reactions vary from "it is a sign of age, the older you get the faster time goes by,” to "I’m glad it is over because Labor Day is coming and with it far fewer people/less traffic,” or "alright, that rather boring month is over (for birding), let the fall migration begin.” It doesn’t matter from what perspective we look at the immediate past but rather that as this is being written on August 1, 2005, the birding curve has swung and every day from now until the end of November, lots of interesting birds, bird behaviors, and weather are coming at us. The birding just keeps getting better from here, looking forward.
The fall migration is the time when the coastline and the Island shine. The islands are the place to be and if you are reading this on the Vineyard, then you are at the right place at the right time. Almost every day, no matter which way the wind blows, there is potential and possibilities for exciting birding opportunities.
Perhaps the wayward red-footed falcon, the first of its kind to grace the Americas, that appeared at the Katama Airpark last summer, first seen on Aug. 8, will magically reappear at the same time and place. This is not as far-fetched an idea as one might think, as there is quite a history of vagrant birds showing up repeatedly on the same date at the same place. The answer to this question will be forthcoming shortly and I, for one, am keeping my fingers crossed that it makes it back to Island shores.
Weather is key
The time has come to keep an eye on the weather and movement of frontal systems. Birds are tuned into atmospheric pressure and the weather in ways we cannot even imagine. They have to be as the very lives of these tiny, long-distance migrants depend on correctly interpreting the weather. Forecasting, predicting correctly the approach of violent storm systems, is a matter of life and death for migratory birds, which have to rely on their highly evolved senses to make critical decisions.
The approach of a tropical storm or hurricane, apt to head this way or be encountered during migration heading south over the next couple of months, is something that birds can actually feel. The low pressure in the eye of the storm and radiating outward can actually be felt by the birds and avoided. The high pressure associated with a cold front and light northwesterly winds, perfect for southbound migration, can also be detected by these winged marvels.
Either of these weather patterns, and any and all in between, have all been dealt with before by birds, long enough to shape the migration patterns that have evolved in these species over the last 10,000 years, since the last ice age. For birders, these weather systems are exciting as they invariably have birds moving with them. Change is all around in the natural world but nowhere more obvious than in bird life.
Woodlands
The breeding season is over for all but a few prolific, multi-brooded species like robins and Carolina wrens. Bird song has dropped off and things have gotten fairly quiet, especially after the sun gets up a little in the day. Birds are feeding heavily, growing new feathers and putting on fat reserves to be used either during migration or for the upcoming winter by permanent residents. Woodpeckers are rather noisy right now, uttering loud call notes. Several callers noted their respective first looks at red-bellied woodpeckers and wondered at the status of this rapidly increasing and common Island resident.
All the land birds are beginning to gather in mixed flocks, usually accompanied by local black-capped chickadees. Listen for chickadees and then find them. Often there will be impressive mixed flocks with many warblers, vireos, flycatchers and orioles mixed in. Already migrant warblers — both yellow warblers and northern waterthrushes — have arrived and are showing up in suitable habitats. Many other species will soon arrive the morning after a cold front passes.
Fields
Thirsting for some rain, the fields and farms are playing host to lots of mourning doves, song and chipping sparrows, American goldfinches, house finches, northern mockingbirds and small flocks of bluebirds. Most activity is around the edge habitat associated with the interface of woodland, beach, or housing. As plants develop more seed heads and migration increases, so does activity in overgrown fields. Neatly mowed or neat fields are relatively uninteresting for birds, as there is little food. The fields really heat up in late September and for the entire month of October, when sparrow migration is at its peak.
Tidal Flats and Beaches
This is where the bulk of the action is and the easiest way to see migrants. Sandpipers and plovers, gulls and terns, and lots of activity as well as the coolest temperatures make tidal flats the place of choice for Island birders for the next couple of weeks. Large numbers of shorebirds can be seen. The best time for finding shorebirds on the Vineyard is during and after bad weather with lots of precipitation causing birds that are over flying the Island to divert to Island shores to ride out the weather. Generally within a few hours after it clears, the birds continue on their way.
Until next week — keep your eyes to the sky.
To contribute
news about your birding activities or sightings, call The Times Birdline,
508-693-6100, extension 33; or e-mail birds@mvtimes.com.
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