Blackpoll Warblers, migrating long distances across the open waters of the Atlantic in fall, are especially vulnerable to the effects of tropical storms. In 2012, most of them had gone south before Sandy arrived, but some other birds were not so fortunate. Photo by Kenn Kaufman.
Sandy was a thousand miles wide and had winds of close to 90 miles per hour as she approached the coast of New Jersey. Most migratory birds weigh only a few ounces, or even less than an ounce for some smaller birds like warblers. Considering the collision of tiny birds and big winds, it stands to reason that bird migration would have been disrupted by the powerful storm. But the effects on birds varied quite a bit, depending on the species involved; here are a few noteworthy examples.
Effects on land birds migrating offshore
Every fall, many millions of birds take off from the east coast of North America, flying south or southeast over the water toward winter homes in the tropics. Some, such as blackpoll warblers and some sandpipers and plovers, may fly nonstop to northern South America. Others, such as Cape May warblers and Bicknell’s thrushes, fly directly to islands in the Caribbean. Once they are out over the open waters of the Atlantic, these migrants are vulnerable to the effects of storms. Hurricanes that make landfall along the Atlantic shoreline often leave coastal areas swarming with exhausted small birds that have been pushed back northward by the winds. Presumably these are the lucky ones, and many more will have perished offshore.
As a very general rule, among North American birds, the long-distance migrants tend to move in the early part of the fall, while short-distance migrants (including most of those wintering in the southern U.S.) tend to move later. The timing of Sandy, relatively late in the fall, means that it probably was less damaging to the long-distance, over-water migrants than if it had occurred earlier. By October 24, when Sandy pounded across Jamaica and headed for Cuba, the majority of these migrants would have completed their travels. Undoubtedly many birds were killed on land, but relatively few would have been caught over the open water.
Within North America, short-distance migrants moving down the coast undoubtedly would have been displaced. To the south of where Sandy made landfall, where winds were from the west, many migrants probably were pushed far offshore. Typical late October migrants such as kinglets, sparrows, and yellow-rumped warblers may have suffered substantial losses.
Effects on seabirds pushed inland
Whenever a hurricane or tropical storm comes inland, birders in the region will race to lakes and rivers to see if any oceanic birds have been deposited there. Seabirds caught up in the spiraling winds often will find their way to the calm eye of the storm and will travel within it, even if it moves over land. When the storm dissipates, they may be hundreds of miles inland.
Sandy brought a scattering of true seabirds far inland. Leach’s storm-petrels appeared on lakes in upstate New York, Pennsylvania, Maryland, and elsewhere. Northern gannets were seen along the Hudson River. A Herald petrel, a deep-water bird that’s usually far offshore, was found in Pennsylvania.
However, the biggest numbers of displaced birds involved species that would be actively migrating in late October. The pomarine jaeger, a predatory seabird that nests in the Arctic and winters at sea, ordinarily would be migrating south offshore at this season. After Sandy’s passage, dozens of pomarine jaegers, possibly even hundreds, were seen in Pennsylvania, including flocks migrating south along the Susquehanna River in the center of the state. To call these numbers “unprecedented” would be an understatement. Red phalarope, another typical offshore migrant in late fall, also appeared on lakes and rivers in the interior.
A displacement of a different kind involved flocks of brant. The Atlantic population of this small goose leaves its high Arctic breeding grounds and spends several weeks in fall in southern James Bay, Canada. Normally, the brant then mostly make a nonstop flight from James Bay southeast to the Atlantic Coast around New York and New Jersey, beginning to arrive in late October. The strong winds of Sandy interrupted the flight this year, shifting large numbers of brant westward and putting them down in places where they are usually rare. Hundreds of brant were seen along the Lake Erie shoreline in Ohio, hundreds along Lake Huron in eastern Michigan, hundreds in southern Ontario, thousands over Cayuga Lake in upstate New York. Locations all around the Great Lakes recorded their highest numbers ever during a brief period centered on October 30th. But within a matter of days, essentially all of these birds were gone, as the tough, hardy brant regrouped and continued their migration to the coast.