Arctic Tern Habitat Model
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Draft Date:
March, 2001

Species:
Arctic tern, Sterna paradisaea

Use of Study Area Resources:
Reproduction. Arctic terns have circumpolar distribution, nesting primarily on small islands off northern Europe, Alaska, Canada, and the western Atlantic coast south to Massachusetts. Alternatively, they may nest miles inland from the sea, and feed in lakes and rivers (Hawksley 1957). Arctic terns winter in the Antarctic and sub-Antarctic (Street 1997).

Habitat Requirements:
Cover. Arctic terns nest colonially, on sandy, gravelly, or sparsely vegetated shores of small islands (Hawksley 1957) or occasionally along barrier beaches. Although they often nest in colonies of their own species (Terres 1995), nesting habitat in the eastern part of their North American range may be shared with common terns, least terns and roseate terns (Hawksley 1957). They nest at edges of the more abundant common tern colonies, initiating nesting somewhat later in the year (Veit and Petersen 1993). Arctic terns seem to avoid islands with shrubs or other woody vegetation, and nest where the vegetation is short or sparse at the time the nest site is chosen (Hawksley 1957). Nests consist of a shallow scrape on the ground (Terres 1995) and are vulnerable to predation on eggs and young by foxes, skunks, dogs, cats and avian predators (Terres 1995, Hawksley 1957, Blodgett 1999). Adults generally escape ground predators but may be taken by owls or raptors; jaegers and gulls also prey on eggs and young and harass adults (Hawksley 1957).

Feeding. Arctic terns feed on flying insects, (Hawksley 1957), amphipods (Abraham and Ankney 1984), euphausids, and small fishes (Braune and Gaskin 1982), in mixed flocks with common and roseate terns (Andrews 1993). Arctic and common terns differ in the sizes of fish brought to their chicks and the specific foraging localities (Hopkins and Wiley 1972). Arctic terns are principally deep water feeders, diving on schools of small fishes in typically oceanic waters (Teres 1995) but adapt readily to changes in food supply (Hawksley 1957). Boecker (in Hopkins and Wiley 1972) reported that North Sea arctic terns fed over more inshore, shallow waters than common terns. In lieu of specific information on feeding ranges of arctic terns, we assumed they were similar to those of common terns. The latter forage up to about 22 km from nesting colonies (Pearson 1968, Duffy 1977, Erwin 1978).  However, most foraging is within 6 km of colonies (Austin 1946, Pinkowski 1980).

Habitat Mapping:
Data Sources: Data depicting arctic tern nesting sites were obtained from the Maine MDIF&W Seabird Nesting Island databases, from New Hampshire Audubon Society (Diane DeLuca), and from Massachusetts Fisheries and Wildlife (Brad Blodgett).

Nesting habitats were scored according to probability of use. Recently active arctic tern nesting  sites were scored 1.0; island sites recently used by common terns (and so offering potential for colonization by arctic terns) were scored 0.5. Other sites historically used by arctic terns (since 1985, but no longer in use) were scored 0.4.

Feeding habitats were mapped around nesting sites currently used by arctic terns. These consisted of marine or estuarine open water areas within 6 km of active nesting sites. Since highest value feeding areas could not be distinguished from other open water areas, all feeding habitats were scored 0.3. This distinctive score also distinguishes feeding and nesting areas in the single (combined) output grid.

Sources:
Abraham, D.M. and C.D. Ankney. 1984. Partitioning of foraging habitat by breeding Sabine's Gulls and Arctic Terns. Wilson Bulletin 96(2):161-172.

Austin, O.L. 1946. The status of the Cape Cod terns in 1944: a behavior study. Bird-Banding 17:10-27.

Andrews, R. 1993. Importance of the Islands in the Gulf of Maine to the Federally Endangered Roseate Tern, Sterna dougallii. MS. 5pp.

Blodgett, B. 1999. Massachusetts Tern Inventory, 1999. MS, 11pp.

Braune, B.M. and D.E. Gaskin. 1982. Feeding ecology of nonbreeding populations of larids off Deer Island, New Brunswick. Auk 99(1):67-76.

Duffy, D. 1977. Breeding populations of terns and skimmers on Long Island Sound and eastern Long island: 1972-1975. Proc. Linn. Soc. NY. 73:1-48.

Erwin, R.M. 1978. Coloniality in terns: the role of social feeding. Condor 80:211-215.

Hawksley, O. 1957. Ecology of a breeding population of Arctic Terns. Bird-Banding 28(2):57-92.

Hopkins, C.D. and W.R. Haven. 1972. Food parasitism and competition in two terns. Auk 89(3):583-594.

Pearson, T.H. 1968. The feeding biology of sea-bird species breeding on the Farne Islands, Northumberland. J. Anim. Ecol. 37:521-552.

Pinkowski, B.C. 1980. Adaptations of Common Terns nesting on an inland reservoir. Prairie Nat. 12:111-113.

Terres, J.K. 1995. The Audubon Society Encyclopedia of North American Birds. Wings Books. Avenel, NJ. p. 468.

Veit, R.R. and W.R. Petersen. 1993. Birds of Massachusetts. Massachusetts Audubon Society. 514 p.