By Bill O'Brian
Roseate terns have a lot going against them, but they have one major effort going for them.
On the downside, habitat for the endangered roseate tern Northeast population has been lost through decades of development and, recently, sea-level rise. And roseate terns are picky about habitat. Furthermore, they depend on common terns to help defend their nests from predators. If that's not enough, roseate terns, which are skittish and prefer not to be disturbed, assemble for pre-migration staging on Massachusetts' Cape Cod precisely when hundreds of thousands of vacationers are there, too.
On the upside, there is the Endangered Roseate Tern Breeding and Staging Habitat Management and Enhancement project funded by the U.S. Fish and Wildlife Service’s Cooperative Recovery Initiative (CRI).
The project is dedicated to enriching roseate tern breeding and staging habitat. It is doing so on a landscape scale involving national wildlife refuges, three major non-Service-owned sites, the Service's New England Field Office and state and nonprofit partners.
The roseate tern Northeast population “uses a network of islands scattered across the landscape” from Nova Scotia and Quebec through New England to Long Island, NY, says Stephanie Koch, supervisory wildlife biologist at Eastern Massachusetts National Wildlife Refuge Complex. “Work done in isolation at a site here and there would not be effective at all. The CRI has helped the partners and land managers come together with
a common objective and increased our effectiveness through shared learning and shared resources.”
Roseate terns, whose chests turn rosy- pink during breeding season, are 15 inches long. From May to July, they nest on small barrier islands from Canada to Long Island. Mid-July and all of August is their staging period.
In mid-September, they migrate to the Caribbean and northern South America before returning to the Northeast the following spring.
Roseate terns nest in common tern colonies and rely on common terns
for defense. “But they are much more selective in their habitat choices within the nesting colonies,” says Koch. “Ideal roseate tern habitat can vary quite a bit, though, depending on the site. In general, roseate terns prefer to nest in habitat with a good amount of cover, more cover than common terns. They'll nest in beach grass, goldenrod and other coastal vegetation. They'll also nest in artificial nesting structures.” Three primary nesting sites are Great Gull Island, NY, and Ram and Bird Islands in Buzzards Bay, MA. At least five refuges host nesting or staging terns: Rachel Carson, ME; Monomoy and Nantucket, MA; Trustom Pond, RI; and Stewart B. McKinney, CT. The project helps land managers to improve habitat via invasive species control, prescribed burns, predator control, terrace building and other techniques and to protect staging birds via public outreach.
August staging is “a really fascinating phenomenon because the entire endangered Northeastern population of roseate terns comes south or north, depending on where they nested, and converge on beaches on Cape Cod and the islands,” says Koch. The period is critical. Fledgling chicks are able to fly on their own but still are being fed by adults. Human disturbance can separate chicks from adults, stress terns and sap their energy before the long migration.
The project seeks to understand staging and encourage public and private landowners and conservation partners to reduce disturbance by limiting human access to sites and educating the public.
In the 1930s, the roseate tern Northeast population was about 8,500 pairs; now it's about 3,000 pairs. “We can do better than that for this species, and it has to be done here – this is where the birds nest,” says Koch. “On a personal level, I want my children to have the same privilege I have of hearing the roseate terns' beautiful call and observing their acrobatic flights.”