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Volume 39 Issue 22 • Nov 23, '09-Jan, '10
now in our 39th season

Nantucket: for the Birds

by Kenneth Turner Blackshaw

Nantucket is like a stage where a continually changing cast of avian characters make love, go to dinner, and sometimes go to war.  As Roger Tory Peterson said, “Birds have wings and they use them.”  And when they do, they often find this special fifteen-by-four-mile drift of sand in the Atlantic.  That is why Nantucket Island is such an important birding location for birds and people who love to watch them.

Nantucket is an island in the midst of a complex evolutionary change. Bird species go back millions of years.  As the last glaciers receded 10,000 years ago, our island was hundreds of feet above sea level and not an island at all.  Now there is no place on the island much more than a few miles from the gigantic ocean that stretches to Portugal.

As the sea levels have risen, Nantucket has continually shrunk from being a hundred miles inland, to a peninsula, and finally to an island.  It is host to an endangered habitat: the sandplain grassland.  At best this is a transitional environment, subject to being swept away by the ocean or taken over by advancing scrub and trees.  Ninety percent of the world’s sandplain grassland habitat is on Nantucket, Martha’s Vineyard, and Tuckernuck.  Species dependent on this habitat are at great risk.  Two larger birds whose presence is easily observed, or missed, include the Short-Eared Owl and the Northern Harrier.  But there are many other species that are subtler in habit that are also affected by the loss of this habitat—birds like the Upland Sandpiper and Grasshopper Sparrow come to mind.

Still, there are many species of birds that reside here year ‘round, pass through, or come just for the season.  An avid birder would have no trouble recording 200 species of birds every year on Nantucket. At every season there is a reason to be out looking.

In the dead of winter one can find at least ten species of gulls.  Observers from inland are excited to see scores of Iceland and Lesser Black-Backed Gulls off the island’s east end.  At the west end there is an incredible flight of Long-Tailed Ducks back and forth each day, as perhaps a million of them commute from the western part of Nantucket Sound to shoals 30 to 40 miles south of the island and back again.  The fact that our climate is tempered by ocean waters that seldom freeze makes Nantucket a place where birds appear that can’t be found elsewhere during the New England winter.

In the spring Nantucket is often the recipient of birds seldom seen in New England.  We call these birds “overshoots.”  These are birds, perhaps on their first flight north, that are picked up by strong, usually southwesterly, wind currents and deposited hundreds or even thousands of miles from others like them.  Birds like Blue Grosbeaks and Summer Tanagers are not unusual on the island at this season.  Swallow-Tailed Kites whose summer range cuts off along the Carolina coast, have been seen here several times.  Even more spectacular are the records of Fork-Tailed Flycatchers, birds from the northern coast of South America.

It is the lucky overshoots that find our island.  Many others probably perish in the cold Atlantic waters, too far away from land when the euphoria of flight leaves them looking for a dry spot.

But even “normal” birding can be exciting here.  Fall migrations of landbirds bring thousands of young warblers this way.  Again, Nantucket may be the last landfall they make because unless they break the pattern of riding the northwesterly winds, their next opportunity to land may be Bermuda. Every year, ships in the Atlantic host some of these weary wanderers, making their first, and last, trip south.  It is estimated that fully 95% of the fall songbird migrants that arrive here are birds that only hatched a few weeks before.

Many of the birds that turn up are warblers, vireos, and flycatchers, not easily observed on their nesting grounds.  Here on Nantucket they are feeding ravenously to stoke up energy for the next leg of their migration that may take them to South America.  They find themselves in habitats that allow them to be quite observable.

Over the last half of the 20th century, ornithologist Edith Folger Andrews banded over 50,000 birds as part of her studies of our island.  In the early 50s I was lucky to be one of her apprentice assistants, helping to band birds.  Many of these birds can be found in Roger Tory Peterson’s Field Guide to the Birds on a plate that is captioned “Confusing Fall Warblers.”  I was confused most of the time, but I was lucky to have a good teacher.

Another group of avian life consists of the birds that come to our island in late spring and summer to nest on our beaches.  These are mainly gulls, terns, and shorebirds.  Over the past 100 years we have seen species become common and then decline, like the Laughing Gull that went from 30,000 in the mid-1930s down to no nests at all after 1972.  The Arctic Tern is another species that no longer nests with us.  Other species like the Herring Gull and Great Black-Backed Gull do very well, often at the expense of their neighbors.  Species of special concern like the Piping Plover and Least Tern lose chicks and eggs every year to their voracious neighbors.  American Oystercatchers, vocal and colorful summer beach residents, have only been nesting here for the past 25 years.

Over the years many climatic trends have affected Nantucket. The most recent is Global Warming.  There’s no doubt that things are slowly warming up and the birds are definitely noticing and responding.  There are several conspicuous bird species around us that were missing 50 years ago.  One seen most every day is the Northern Cardinal.  Another that is not so visible but certainly as hear-able is the Carolina Wren.  These are two species that don’t migrate, spending their lives close to where they hatch and only increasing their range by population pressure.  The wrens, particularly, are at the edge of their survival range on Nantucket.  Severe winters like the one we had in 2003 and 2004 kill most of them.  Their strident whistled “teakettle” song seemed strangely absent the following year, but in a few years there were as many as ever.

Other species that migrate have pushed their nesting range north to reach Nantucket.  Two very noticeable ones are the Great and Snowy Egrets.  These lovely, graceful white herons are now seen along Nantucket’s shores from early April and sometimes into December.

Global warming is also causing the world’s icecaps and glaciers to melt and scientists tell us higher sea-levels will result.  This takes us back to the initial picture I painted showing Nantucket’s progress from well-inland to shoreline with the decline of the last ice age.  These are changes that take thousands of years and are part of the system of climatic cycles our planet will always experience.

In the meantime, birds must find their place in the web of all living things, humans included, and continue to do the things that promote their survival. The adaptations that cause species change can only move at a snail’s pace compared to man’s ability to swiftly and dramatically change and destroy habitat.

On Nantucket, man’s opportunity to do this is tempered by society’s feeling that responsible land management involves preservation of great chunks of our ever-shrinking island.  We are fortunate have a social environment where much of the land has been preserved that might otherwise have been lost to development.  We have the Nantucket Land Bank, the Nantucket Conservation Foundation, and the Nantucket Land Council, in addition to the Maria Mitchell Association, the Linda Loring Nature Foundation, and the Trustees of Reservations.

So Nantucket is a very special place among coastal communities in that our avian friends can still find habitat in which to live. We are standing on a very special piece of geography where the continent and ocean come together providing both migration route and living habitat for hundreds of species. Tourists may come here for beaches, relaxation, and cooler weather. The birds they find around them are a bonus.

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