Storm Flung Vagrant Birds

This column celebrates its first anniversary today. As if to commemorate the event, Helen Bates called a few days ago to give me a report of a person in Westfield seeing a sandhill crane flying over. By chance last week's column was about cranes and herons. The sandhill crane is very rare in new England, its range extending only to Michigan. If the bird was a sandhill, what could have brought it here?

The title of this column begins to answer that question. Birds are creatures of the air, and their travels are dependent on conditions of the envelope of air that enwraps the earth. In late summer and fall the weather channel shows some startling satellite imagery from orbit. Cameras track the movement of clouds and storms over land and sea with amazing clarity and beauty.

The pictures bring to mind the fragility of life caught in such violence. Birds might seem the most fragile of all, except that their powers of flight have evolved to handle most of the vagaries of wind and rain. The hurricanes that just raked the east coast did displace many birds, but they are amazingly resourceful and recover quickly.

That sandhill crane might have been a storm blown bird from the central prairies of Florida. Most birders in New England who long for a view of unusual birds from the far south are out in the field the minute a hurricane passes through. The latest storm went right up the Connecticut Valley, so we were anticipating exotic visitors when dawn came and the eye was right over us.

It was not to be, as the only report was of a common tern and two black terns from Turner's Falls. Though marvelous flyers, most terns are light-bodied and prone to be buffeted and borne off course by high winds. These birds were caught up from the coast of New Jersey or Long Island and deposited on our river. When the wind turned to the northwest, they quickly rode them back to the ocean.

To find the tropical birds we were hoping for, one had to be on Cape Cod that morning. The cyclonic winds that revolve around the center carry birds ahead of the storm to the east and south against the shore. Many end up in Cape Cod Bay, pushed right onto the bay beaches and unable to fight the wind around the curve of the outer cape.

When the storm passes and the wind switches to the northwest, they are pushed into the crook of the Cape's arm at Eastham. With clearing skies, you can stand at First Encounter Beach and watch the ocean birds fly past very closely.

After this hurricane, watchers there observed all the regular seabirds that live off our New England shore, but they also found a few sooty terns and a bridled tern. The sooty tern is a worldwide tropical species that nests on islands in the Gulf of Mexico. The very similar bridled tern nests on islands of the West Indies and Bahamas as well as in the Caribbean. Both have much darker backs than the regular coastal terns of New England.

If you take a boat trip out from Key West Florida in the early spring, you can find bridled terns coursing the open sea in their relentless quest for food, which they pluck from the surface of the ocean. Arriving at a small group of islands to the west of Key West, called the Dry Tortugas, you will find an immense nesting colony of sooty terns.

Both these terns live in tropical waters around the globe, the bridled tern staying closer to land masses. The sooty tern ranges far over the open oceans. Atlantic populations disperse eastward after the breeding season, many spending the winter off the African coast. It is thought to be one of the most numerous birds in the world.

Two sooty terns were found on the Connecticut River after Hurricane David in 1979. Every time another storm comes up the coast and weakens over New England, local birders hold their breath and hope to find one. For most of us our first encounter with these tern travelers from the tropics is still to come.