Roseate tern (Sterna dougalii) - Threatened
Roseate Tern on Petit Manan Island, Maine Coastal Islands National Wildlife Refuge, Me. Photo Credit: Kirk Rogers, USFWS digital library.
Habitat: Offshore islands free of dense woody vegetation
Occurs in Maine: Currently nests on Stratton, Outer Green, Jenny, Pond, Eastern Egg, Seal, Metinic, and Petit Manan Islands.
Threats: Disturbance from humans and associated activities, predation, habitat modification, overfishing, and sea level rise.
Species Description and Life History
The roseate tern was federally listed as endangered in 1987 in its breeding range from eastern Canada to North Carolina and threatened elsewhere in the Western Hemisphere.
Roseate tern. Credit: USFWS
|The roseate tern is a graceful bird, 14 to 17 inches long with a wingspan of about 30 inches. It resembles the common and arctic tern, with which it nests in mixed species colonies in Maine. Its beak is predominantly black
(in contrast with common tern with orange beak with black tip and arctic tern with all orange beak). Its back and upper wings are pearly gray and underparts are white with a pink tinge, hence its common name. The tip of the white tail extends well beyond its wing tips when perched.
During the nesting season, Maine roseate terns feed primarily in near-shore habitats (shall sand shoals, tide rips) on sand lance, and larval forms of herring, hake, and other small fish. Roseate tern foraging areas are not well known, but can be 10 to 15 miles or greater from nesting islands.
About 200 to 250 pairs of roseate terns nest on Maine coastal islands. Roseate terns return to Maine nesting islands in mid-May. After courtship a clutch of One to five eggs are laid in mid-May to mid-June. The nest is a simple scrape on the ground in dense vegetation or under rocks or driftwood. Both parents incubate the eggs, which hatch in about 23 days. The chicks fledge 22 to 30 days after hatching.
Primary threats affecting tern populations in Maine are gull predation, habitat loss, human disturbance, food shortages, oil spills, offshore wind development, and long-term effects of sea level rise.
The North American subspecies of the roseate tern is divided into two breeding populations, one in the northeastern U.S. and Nova Scotia (listed as endangered), and one in the southeastern United States and Caribbean (listed as threatened). Roseate terns from throughout the northeastern breeding population often congregate in large flocks at staging areas in Maine in August and September prior to their fall migration. Staging areas include the beaches at the mouth of the Kennebec, Stratton Island, and tidal creek outlets throughout southern Maine. These are important habitats for the birds to gain energy reserves prior to migrating far offshore to wintering habitats in South America.
Distribution in Maine:
Roseate terns currently nest on Stratton, Outer Green, Jenny, Pond, Eastern Egg, Seal, Metinic, and Petit Manan Islands. These islands are all managed for seabirds by State, Federal, and private groups. Historically, roseate terns nested on additional islands in Maine. They could reoccupy some of these islands in the future. Current and historic roseate tern islands are designated Essential Wildlife Habitat by the Maine Department of Inland Fisheries and Wildlife. Maps can be viewed at the “Beginning with Habitat” mapping service.
Examples of actions that may affect this species
The following is provided as technical assistance only and is not intended as a comprehensive list of all activities that may affect this species.
On a tern nesting island:
- coastal wind turbines
- aquaculture facilities located within one half mile of nesting islands
- construction of any new permanent or temporary structure on islands
- new or modified island management practices including but not limited to seabird management, operation of lighthouses and associated structures, installation of radio equipment, beacons, and navigation markers
- vegetation planting or removal, new or increased discharges of herbicides, pesticides, or environmental contaminants
- boat launching and landing facilities
- any new or expanded human activity during the nesting season of May 15 through August 31, especially but not limited to activities involving human activity on nesting islands
Within 1.0 mile of a tern nesting island:
- dredging activity
- aquaculture facilities
- wind turbines
- permanent or temporary increases in noise or disturbance between March 15 through August 15, including but not limited to major construction work and operation of low-flying aircraft (less than 2,000 feet above ground level)
- fireworks displays
Best Management Practices
The following Best Management Practices are examples of typical Conservation Measures frequently recommended by the Maine Field Office in the course of consultation or technical assistance (example from New Jersey).
- protect seabird nesting island and adjacent waters from further development, especially human dwellings, fishing piers, docks, wind turbines, and aquaculture facilities.
- maintain at least a one-quarter mile buffer around nesting sites to minimize human
- disturbance to nesting roseate terns. Avoid noise and disturbance during the nesting season (May 15 through August 15)
- keep boat activity more than 660 feet from seabird nesting islands. If the birds flush, you are too close. Keep pets and people (other than seabird managers) off islands during the nesting season.
- control predators, including but not limited to gulls, mink, and raccoons
- manage native vegetation at nest sites and control exotic vegetation
- use artificial nest sites to provide additional cover at some nesting islands
- establish and maintain an emergency response plan for oil and chemical spills.