Ask an Island Expert: What bird makes those big nests on top of poles around the Island?

A male osprey delivers a fish at its nest at Long Point.

Those are osprey, or Pandion haliaetus, if you’re a biologist. A summertime resident on the Island, the osprey is a common nesting species and a much-loved part of our bird life. Under wholly natural conditions, ospreys nest mainly in large, dead trees. Such trees don’t last long in the windy Vineyard environment, and these days, Island ospreys build their massive nests primarily on poles (over a hundred exist on the Island) erected specifically to attract the birds. Pairs of osprey stay mated for years, using and adding onto the same nest. The return of these migratory hawks in mid-March from their wintering grounds (largely in South America) could be called the unofficial start of the Vineyard spring; year-rounders vie for the honor of making the first confirmed sighting. Like many other birds of prey, ospreys were driven nearly to extinction in the 1950s and 1960s by the widespread use of pesticides like DDT, which concentrates in the tissues of predators and fatally thins the shells of their eggs. Since DDT was banned in 1972, hawk populations of all kinds have steadily rebounded. The Vineyard program of erecting osprey nest poles, coincidentally, started around the same time, and nowadays, roughly 75 pairs of the birds occupy the Island each summer. An old common name for this excellent bird is “fish hawk,” and that sums up the most important thing to know about the osprey: they feed almost 100 percent on fish, which they capture by means of spectacular, foot-first plunges into the water. What could be more appropriate for a Vineyard seasonal resident? Enjoy these spectacular birds, which represent the spirit of the Vineyard and reflect a triumph of conservation.