Saturday, August 25, 2007

When the Swallows Gather

I make periodic trips to Plum Island and the New England coast because I can see numbers and varieties of birds that can’t be seen in southern Vermont - shore birds and waders in Spring and Fall, gulls, diving ducks, and pelagics in the winter.

But mid-August is not a good time to go to Plum Island. The mosquitos are voracious. The green headed flies are at a vicious peak. The sun is baking hot. Parking is a premium as beach goers pursue their melanomas.

Nevertheless, I make a trip to Plum Island in mid-August anyway, because that is when nature has a show - one of her great shows. It’s a show that rivals the arctic migrations of the caribou, or the movement of the herds across the Serengeti. It is a winged show. The swallows are gathering - by the thousands and, at their peak, by the tens of thousands. They are predominantly Tree Swallows, but the purpose is not to pick out different species. The purpose is to stand in the midst of the abundant life.

Some years I have been early, or late, and have missed the show. I don’t think I was there at the peak numbers last week, but there was never a moment during the day when there were not hundreds of swallows on the wing, and any bush might be alive with swallows resting, but restless.

Entering the Parker River Refuge, there was a sign cautioning motorists about swallows in the road. Within yards, we had to pause, creeping slowly forward until two hundred swallows took flight.

Along the refuge road there were gatherings that numbered in the thousands. We stood on the road in the middle of one roost. Trees and bushes were covered with swallows, resting a moment, bursting into flight, darkening the sky, coming back to roost - restless, swirling life - a conclave and convention meeting to prepare for the great journey ahead.

Tree Swallows do not make the epic migration that many of our summer birds make. They winter predominantly along the southern Atlantic and Gulf coasts, and in the West in Baja California and the coast of Mexico. 170 years ago, Audubon saw huge flocks wintering in Louisiana, and still today flocks are often estimated in the hundreds of thousands. As sub-tropical winters have moved northward, so also have wintering swallows. I have seen Tree Swallows throughout the winter in Cape May, NJ, and it is not uncommon to find them wintering even further north. Seventy years ago, an observer studied a small flock of swallows which stayed the entire winter on Long Island, NY; most survived.

Tree Swallows can winter as far north as they do, because, unlike most other American swallows, they eat a substantial amount of vegetable matter. One study found that 20% of their food was vegetable - a variety of seeds and berries, but with a strong preference for the fruit of the bayberry.

Because Tree Swallows winter along the southern North American coasts, they return early to their northern breeding areas. Last year I saw Tree Swallows on Lake Champlain on March 28. By early-April, they are regularly reported in our neighborhoods, and by mid-April (barring a late winter storm which may cause them to withdraw) they are here to stay. By late April they are staking their claim to nest sites, often competing - successfully - with bluebirds, starlings, and House Sparrows for those boxes and holes.

Tree Swallows nest early, and raise their young. Unusual among our swallows, they undergo a complete molt before migrating. They gather in huge flocks and migrate late.

Arthur Bent summarizes this annual convocation: “Fall is a season of drama in the tree swallows’ yearly cycle. A single idea, or an urge, seems to grip every swallow in the land. The nesting season with its quarrels over, the swallows draw together with a common interest in preparation for their next step, the long migration they will take in companies of hundreds or thousands. In August and September we see them gathering in the great marshes by the sea, where they linger for many days in ever-increasing numbers, young and old.”

Last week on the barrier Plum Island, the swallows were gathering. Hundreds mingled restlessly in the bushes along the road. Some swallow hiccup sent them into the air, their mass creating a shadow across the road, before they settled again, briefly.

This annual Fall massing of swallows among the marshes of our seacoast seems to have survived, to some degree, the coastal development which has decimated the numbers of so many other species. In the 1830s, J.J. Audubon’s friend, Dr. Bachman, wrote that he “saw such an immense quantity of this species of birds that the air was positively darkened. As far as the eye could reach, there were Swallows crowded thickly together, and winging their way southward; there must have been many millions!”

These early naturalists observed North American fauna before it was drastically altered by the explosion of the human population. The line runs from a primeval past through these naturalists to the gathering of swallows today. The continuity in this line sets the swallows apart from other huge numbers of birds which we may commonly see and whose numbers may be as great, or greater, than that of the swallows.

For example - blackbirds. Huge flocks of blackbirds can be seen in Fall and Winter. They are often mixed flocks with starlings, a non-native species, and cowbirds, a Great Plains native which has colonized the opened lands of the continent. Or pigeons - the urban flocks all derive from feral birds brought over by settlers. Or Canada Geese - these adaptable birds winter by the thousands in the Connecticut River’s open water, and many travel but a few miles from their wintering fields to their breeding ponds. Most of these large geese flocks are very different from what the early naturalists observed; then the Canada Geese were almost all Arctic nesting birds which wintered in the deep south and whose New England presence was limited to a stopover on their journey.

But as nearly as we can tell, the gathering of the swallows from the vast continental interior to the marshes, grasses and dunes along the sea coast in the Fall, has been an annual event since the glaciers receded and tundra became forest. This glimpse of a primeval past draws me to the New England coast at this time of the year. Thousands of swirling and swooping swallows tell me that the natural order is highly prejudiced in favor of profligate life. It is a system that has served earth’s many life forms exceptionally well - until very recently when one of those life forms, in its profligacy, has gone dangerously amok.

The swallows, at least, seem to be maintaining their balance. I doubt that they are gathering to celebrate, but I celebrate their gathering, and thank them for it.

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