Moon at dusk on Sunday, Sept. 23, when the wind was calm. By midnight it was blowing 25 mph form the northwest. At dusk, millions of birds departed from southern Canada and northern New England, flying by the light of this moon. At dawn, birds were everywhere, forced by the strong wind toward the coast and farther - out over the ocean. Photo by E. Vernon Laux
Monday morning, the first full day of fall, I awoke before dawn and walked downstairs onto the back deck. I was thrilled by what I heard. Emanating from the black sky were the nocturnal flight calls of migrant birds. There was a lot of noise coming from the night sky, meaning that there was a substantial nocturnal migration of land birds.
These flight calls are very different from the calls and songs that the birds make when we usually hear them. These nocturnal contact notes, chips, zits, and slurred notes are much different and we have no point of reference as to which bird is making what noise. But that is slowly starting to change. With a lot of research and practice at listening to nocturnal flight calls, we are able to start identifying a good number with absolute confidence. But that is just a little part of the story of interest to only a few insomniac or Big Day birders. It is fascinating.
These small birds left the north woods last night just after dark. Coming from Ontario, Quebec, New Brunswick, and the Canadian Maritimes, or from upstate New York or northern New England, these winged marvels, weighing just scant grams, stun my human self when I consider the physical enormity of their journey. Stop and ponder for a moment about the lives of these small life forms flying overhead while you are asleep.
Bird populations are at their annual peak right now at the end of the summer breeding season. Most of these birds are young birds, performing their first migration south as they have only been out of the egg since hatching in June or July of this year. After they first leave their nests they continue to be fed by adults for a few days or longer and then it's bye-bye junior - you are on your own. The birds then must master flying, catch food, find water, avoid predators, and find safe places to roost at night. They have to jump right into living and surviving without the benefit of schooling or much parental guidance.
Then throw in the fact that the boreal or deciduous forest where they were hatched becomes an inhospitable wasteland for insect-eating birds for much of the year. They must move, migrate, or face certain death. What a life.
The young birds gather in loose mixed flocks with others of their kind as well as many other species. There is safety in numbers for little birds as many eyes make for a better chance of spotting potential dangers. All birds have an alarm call.
So, these young birds, three or four months old, must now make their way from the north woods to the tropics, wherever its species goes in winter. Through inherited genetic information - a coded microchip of sorts - this bird makes all the necessary physiological adjustments. It goes on an eating binge, called hyperphagia. This all-out eating enables the bird to double its body weight in less than two weeks.
The weight is stored as subcutaneous fat that the bird is then able to use as fuel during its nocturnal flights. The byproducts of metabolizing the fat during powered muscular flight are water and heat. The birds have evolved into nocturnal migrants for many reasons.
It is cooler during the night, much cooler, so that the overheated birds powering themselves by rapid flapping by using the largest muscles in their bodies, the pectorals that power flight, are able to dissipate its effects by flying in the cold night air. They escape the brutal effects of the sun. The air at night is also much calmer without the updrafts created by thermal energy during the day, making it easier for the small birds to fly without getting buffeted by updrafts and crosswinds.
Back to last Sunday night and Monday morning's migration. It was amazing and birds were everywhere. This time of the year is full of activity and action in the natural world. Bird migration reaches a crescendo on the Vineyard. Migrants, large and small, flying high and low, during the day and at night, make their way onto, over and past Vineyard shores. Their comings and goings, the volume of individuals and diversity of species, offer an endlessly fascinating mosaic of bird populations and their movements.
Predicting the days and, particularly, the nights when there will be a major movement of birds, is a work of art still in progress. For some, it's a lifelong game, a skill to be learned and a source of unending guesswork. It's a puzzle involving the date, frontal systems, wind direction and speed and The Weather Channel. Once all these factors are considered, the luck factor enters. It is good to be lucky.
Occasionally, and even with some regularity, one can hit the nail on the head and get it just right. But just when you think you finally have perfect conditions for the big flight or "wave" of birds, some other variable raises its ugly head and there are no birds, when you predicted thousands. It is a most challenging pursuit.
The fact that birds migrate is indisputable. The magic of it, its compelling primal urge, strikes many an observer or witness to the spectacle as very real. Countless books have been written and more will follow concerning migration and especially that of birds, by far the planet's most mobile creatures.
October is the absolute best time on the east coast and the Vineyard to witness large and concentrated movements of birds. Cape May, N.J., is probably the most well-known location to witness this phenomenon but many other coastal promontories, offshore islands and peninsulas offer something similar, if on a reduced scale. The western tip of Martha's Vineyard, the Gay Head Cliffs in Aquinnah, offers the best vantage point in Massachusetts to witness large flights of birds in the fall.
While birds migrate almost continually in good weather in the fall, bad weather has the effect of putting a big damper on their movements. Storms and long periods of inclement weather with lots of precipitation basically halt their southbound progress.
The weather, for the most part has been too good, as far as this writer is concerned, to concentrate the migrating birds. This is good for bird populations as more first-time migrants should reach their respective wintering grounds surviving the rigors of their perilous journey. Many years of bad weather can have devastating consequences for migrants.
This year there have been many mornings with good numbers and variety of species. More are expected and this time period is always good. Whether it will be awe-inspiring remains to be seen. But if you have an interest in the outdoors and even a casual interest in birds, make sure to keep a pair of binoculars nearby over the next couple of weeks.
Until next week - keep your eyes to the sky!
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