STATE THREATENED Arctic Tern (Sterna paradisaea) Stephen Kress Description and other seabirds. Nesting islands are usually The arctic tern is the champion “globe trotter,” treeless and covered by short herbaceous vegetation. annually migrating over 15-20,000 miles round-trip Arctic terns prefer to nest on bare rocks and from its nesting areas in North America to wintering beaches, presumably because their short legs pre- areas in the Antarctic. The arctic tern is a graceful, clude movement through tall, dense vegetation. Of medium-sized seabird (length 15 inches, wingspan the 3,000 islands off the coast of Maine, at least 150 31 inches) with long, pointed wings and a long, have been used by nesting terns in the last century. forked tail. In the breeding season it has a light gray Arctic terns currently nest on only 10 islands in body and belly and a white rump and tail. Its black Maine. cap and nape are separated from its gray throat by a white facial stripe. The arctic tern is distinguished Life History and Ecology from other tern species by its deep red beak. Com- Arctic terns return to their breeding grounds mon terns have red beaks tipped in black, and when sexually mature at 3-5 years of age. However, roseate terns generally have all-black or salmon- some birds may breed as early as two years old. After colored beaks. they breed for the first time, they exhibit high fidelity to a nesting island, and often return to the Range and Habitat same breeding colony yearly. They arrive at breed- Arctic terns have the longest annual bird migra- ing islands in Maine in mid-May. tion known. After leaving North America, they fly After elaborate courtship flights, ground dis- across the North Atlantic, travel south along the plays, and ritual feeding, terns establish pair bonds coasts of Europe and Africa, and winter in the and select a nest site. Two eggs are laid between Antarctic – a distance May 20 and June 10 in a simple scrape that is often of over 10,000 miles! lined with pebbles, shells, or vegetation. The incuba- Their return route may tion period lasts 20-24 days, and both parents share be along the coast of responsibility for incubation. Chicks leave the nest South America. within days, but continue to be fed and brooded by Maine’s arctic the parents. Fledging occurs in 21-28 days. Within tern population is at 2-3 days after fledging, they begin to accompany the southern edge of parents on short flights to nearby feeding areas, and the species’ range in generally depart the colony within two weeks. Fall eastern North America. migration begins in mid to late August. Here the terns nest Arctic terns feed on small fish and crustaceans, primarily on a few which they capture by plunging into the water and outer coastal islands, catching with their bills. Primary foods eaten in Maine include white hake, Atlantic herring, and Range in Maine always in close associa- Known locations tion with other terns sand lance. The terns may forage up to 10 miles Maines Endangered and Threatened Wildlife ©2003 Maine Department of Inland Fisheries & Wildlife • away from their nesting island, in deep water, rocky tion declines, and arctic tern numbers have stabi- shores, upwelling areas, and over schools of preda- lized at about 2,500 pairs. This is still far below tory fish. Some individuals specialize in taking historic levels. More than 90 percent of Maine’s shrimp and small amphipods (shrimp-like animals). breeding population nests at only three sites – Terns can be long-lived. The longevity record for Machias Seal Island, Matinicus Rock, and Petit an arctic tern is 34 years! Manan Island. Because of food limitations and gull predation, arctic terns have not recolonized many of Threats their former nesting areas. Arctic tern nesting islands The primary causes of declining tern numbers in are designated as Significant Wildlife Habitats under the Gulf of Maine are gull predation, human distur- Maine’s Natural Resource Protection Act or as bance, and food shortages. Gulls arrive on nesting Protection Fish and Wildlife areas under the Land islands earlier than terns, occupy the best nesting Use Regulation Commission. areas, and drive terns away. Gulls also eat tern eggs, chicks, and sometimes adults. Habitat on a few Recommendations: islands has been lost because of the construction of ✔ Protect seabird nesting islands and adjacent permanent or seasonal dwellings. Human distur- waters from further development, especially human bance on islands can cause nest and chick abandon- dwellings, fishing piers, docks, and aquaculture ment and increase gull predation. Terns feed on the facilities. Review Essential Habitat maps and immature forms of many commercially valuable guidelines prior to development near roseate tern fish. Fisherman may compete with terns for species islands. Consult with a biologist from MDIFW and like herring and hake. Nesting productivity is low in the U.S. Fish and Wildlife Service to assist with years of poor food availability or adverse weather planning. conditions (rain, fog) that prevent terns from ✔ Municipalities should strive to prevent develop- finding food. The recent collapse of some commer- ment of seabird nesting islands and adjacent waters cially valuable fish stocks may have adverse effects and identify these areas in comprehensive plans. on tern populations. Consider protecting a ¼ mile buffer around seabird nesting islands. Conservation and Management ✔ Use voluntary agreements, conservation ease- Prior to passage of laws protecting migratory ments, conservation tax abatements and incentives, birds, arctic terns were harvested to supply feathers and acquisition to protect important habitat for for the millinery trade (to make women’s hats) and threatened and endangered species. ✔ their eggs were collected for food. Passage of the Stay off seabird nesting islands during the Migratory Bird Treaty Act of 1918 provided protec- nesting season (April 1 to August 15). If visitation is tion for migratory birds, and by 1931 an estimated approved (e.g., commercial tours to a seabird 8,000 pairs of arctic terns nested on the coast of island), remain on designated paths and in blinds to Maine. However, since the 1940s, arctic tern minimize disturbance. ✔ numbers have declined because of predation and Keep boat activity more than 660 feet from competition with gulls. Most of the population is seabird nesting islands. If birds flush from the island, now concentrated on a few islands managed by you’re too close. ✔ conservation groups. The arctic tern was listed as Keep all pets off islands. Do not introduce threatened in Maine in 1997 because of past de- mammalian predators. ✔ clines and because the population is nesting on only Locate aquaculture facilities farther than ¼ mile a few islands. from seabird nesting islands. ✔ Recovery of Maine’s island nesting tern popula- Avoid overfishing and polluting nursery areas for tions (arctic, common, and roseate) requires inten- herring, hake, and other fish stocks important as sive management. Since the 1970s, terns have food for seabirds. ✔ disappeared from most of their former nesting Do not use gill nets near seabird islands or islands. Intensive management is occurring on 10 known feeding areas. ✔ tern nesting islands. Management includes removal Do not dump oil, litter, or waste overboard. or control of competing gull populations, use of Even small amounts of oil can kill birds. Seabirds decoys and sound recordings to attract terns, and are often injured by eating plastic particles from maintaining the presence of tern managers to trash that are mistaken for food. ✔ protect the birds from human disturbance during Avoid overboard discharge of fish waste or bait. the nesting season. Management has halted popula- Predatory gull populations have increased because of this readily available supply of food. • For more information: MDIFW Endangered Species Program • 207-941-4466 • www.mefishwildlife.com •.