Last year, the Roseate Tern population in the United States reached its highest number since 1987, when the northeastern U.S. population was listed as Endangered under the Endangered Species Act. According to the Massachusetts Division of Fisheries and Wildlife, the 2018 U.S. estimate was 4,552 pairs. Canada had an estimated 51 pairs.
The rebound is due in large part to successful habitat restoration and predatory gull management at the birds’ three largest breeding colonies, located along the Atlantic coast in Massachusetts and New York. Living much of their lives on the open ocean, Roseate Terns spend only a few months on rocky islets, where they nest. They winter off the northeast coast of South America and in the Caribbean.
Overall, this population estimate is great news, but Roseate Tern numbers remain short of the recovery target goal of 5,000 pairs. And in recent decades, encouraging increases have been followed by declines; possible causes include climate change, sea-level rise, loss of food to commercial fishing fleets, and unknown dangers in the birds’ tropical wintering range.
A new threat is also growing: Offshore wind energy development may provide a collision or displacement hazard to the terns and other seabirds. While the Block Island Wind Farm in Rhode Island currently is the only offshore wind facility operating in the U.S., several other areas have already been leased for development in southern New England, including sites in federal waters off the coast of Massachusetts, Rhode Island, and Long Island, New York.
The majority of these prospective wind-energy projects fall within foraging areas used by Roseate Terns before, during, and after the breeding season. Confirming this hazard, new tracking studies have documented Roseate Terns crossing the areas designated for wind-energy development. American Bird Conservancy and other conservation organizations are closely monitoring this potential threat. We’re recommending that projects not be sited in high-risk areas for terns and that a mitigation fund be created to pay for the population’s continued recovery.
A version of this article was published in the September/October 2019 issue of BirdWatching.