Wednesday, August 10, 2005

Hundreds of Ospreys, Thousands of Ospreys: Shifting Baselines

The comeback that ospreys have made in Connecticut, referred to the other day in a story in the New London Day, is indeed impressive – an estimated 250 nests where not long ago there were just a handful. After I posted an item about it on Monday, I got an e-mail from Tom Baptist, executive director of Audubon Connecticut and the co-author (with Joe Zeranski) of Connecticut Birds. Tom filled in a lot of the details about the fall and rise of ospreys, and also made an implicit point about shifting baselines – that is, 250 osprey nests are a lot compared to when things were bad, but compared to when things were good, 250 nests are not a lot at all. Here’s what Tom wrote:

In our region, ospreys have been an icon for the ecological ravages of chlorinated hydro-carbon pesticides and habitat alteration. In the 1800s, ornithologists called this species “abundant,” and, at that time, the nesting population in and around Long Island Sound was estimated to exceed 1,000 pairs. Several authors noted declines in the number of ospreys in this region during the first half of the 1900s, possibly related to the destruction of coastal marshes and water pollution. But, by all measures, the osprey population remained robust until after World War II and the initiation of the widespread use of DDT and similar pesticides. For example, a 1938 survey in the tidal portion of the Connecticut River counted more than 200 osprey nests!

In clear correlation to the human use of pesticides in the 1950s and 60s, scientists documented a 31% annual decline in the Long Island Sound osprey nesting population at that time, and by 1963 only 24 pairs were found in all of Long Island Sound. In 1970, eight pairs nested in Connecticut, and that number was reduced to one active nest in 1974. DDT was banned for use in 1972, and a concerted effort to erect nesting platforms (coupled with the importation of eggs from Chesapeake Bay populations to Long Island Sound) generated an annual population increase of 8 to 10% after 1980. At present, the Long Island Sound nesting population of ospreys is 50% to 60% of the pre-DDT numbers.

The incredible decline and subsequent recovery of nesting ospreys in Long Island Sound sets the stage for an interesting anecdote involving Audubon Greenwich’s effort to assist the recovery of ospreys in Greenwich. In the fall of 2004, Audubon representatives approached Greenwich officials about the possible placement of an additional pole and nest platform on the island in the center of Eagle Pond at the fabled Greenwich Point Park. The request was denied on the basis that the platform would degrade the “quality” of the view of the pond and its tall statue of an eagle, with its glorious wings spread wide, rising from the island in its middle. Well, local ospreys had their own opinion about the Town’s rejection of Audubon’s request, constructed this spring a large stick nest upon the wings of the eagle statue, and successfully fledged two young this summer from the new nest. A check of the nest yesterday [i.e. Monday, 8/8] revealed that one full-grown juvenile remained there with its parents beckoning nearby, and the nest nearly obscures the entire eagle statue.

Since the mid 1980s, and with the support of conservation and recreation officials of the Town of Greenwich, Audubon paid for the construction and installation of eight osprey poles and nest platforms in Greenwich. Two others have been installed by individuals. This summer, eight pairs successfully nested in Greenwich, including the pair that built a home and raised a family atop the eagle statue at Eagle Pond. This was a record number of successful nests for Greenwich.

There are at least three relevant points to this anecdote. First, as ospreys have shown, birds are susceptible to human-induced changes in the environment and thus are extraordinarily useful barometers of the health of the ecosystem. Second, despite the concern of many people and the considerable human effort that assisted the recovery of ospreys, some people now perceive ospreys as less important than the “quality” of a view across Eagle Pond at the exclusive Greenwich Point Park. Third, the recovery of ospreys is proof that informed and intelligent human intervention can produce positive results, to the benefit of wildlife and people.


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