JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Ecological Society of America is collaborating with JSTOR to digitize, preserve and extend access to Ecology.Abstract. Several multistratum capture-recapture models were used to test various hypotheses about possible geographic and temporal variation in survival, movement, and recapture/resighting probabilities of 2399 adult Roseate Terns (Sterna dougallii) colorbanded from 1988 to 1992 at the sites of the four largest breeding colonies of this species in the northeastern USA. Linear-logistic ultrastructural models also were developed to investigate possible correlates of geographic variation in movement probabilities. Based on goodness-of-fit tests and comparisons of Akaike's Information Criterion (AIC) values, the fully parameterized model (Model A) with time-and location-specific survival, movement, and capture probabilities, was selected as the most appropriate model for this metapopulation structure. With almost all movement accounted for, on average >90% of the surviving adults from each colony site returned to the same site the following year. Variations in movement probabilities were more closely associated with the identity of the destination colony site than with either the identity of the colony site of origin or the distance between colony sites. The average annual survival estimates (0.74-0.84) of terns from all four sites indicate a high rate of annual mortality relative to that of other species of marine birds.

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Marine birds are useful as bioindicators of environmental pollution in estuarine and marine environments because they are often at the top of the food chain, ubiquitous, and many are abundant and common, making collecting possible. Seabirds have the advantage of being large, wide-ranging, conspicuous, abundant, long-lived, easily observed, and important to people. Many species are at the top of the food chain where they bioaccumulate contaminants with age. One disadvantage is that many species are migratory, making it difficult to determine where exposure occurred. This can be eliminated by using sedentary species or young birds that obtain all their food from parents. Further, noninvasive collection of feathers can be used to assess heavy metal levels, both from current collections and from historical collections in museums dating back centuries. Marine birds can be used as bioindicators in many ways, including tissue levels of contaminants, epidemiological field studies of effects, and experimental and laboratory studies of dose and effects. Examples from our research indicate some of the ways marine birds can be useful as indicators and sentinels of contamination, particularly by using young birds and feathers.

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