LTREB Renewal: Long-term Investigation of Territorial Behavior and Population Dynamics in the Common Loon

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This long-term project focuses on common loons, diving birds that breed on lakes in the northern U.S. and are famous for their loud, humanlike vocalizations. Both sexes defend territories from intruders, which often take them by force. About one-third of all male takeovers are fatal for the displaced breeder; females seldom fight to the death. Current theory predicts that lethal battles should be frequent in short lived animals because they have few reproductive opportunities, but organisms such as loons should never fight to the death because they are long-lived and territories are plentiful. Over the course of ten years, the project is testing three hypotheses to account for fatal fighting: 1) fatal battles constitute a 'terminal investment' for old, declining males, 2) males that fight to the death defend chicks well, which offsets their hyper-aggressiveness, and 3) extreme familiarity with a territory causes fatal battles. To test these hypotheses, the researchers follow and observe a large number of marked individuals, measure body mass of captured loons, and analyze territorial fights, usurpations and survival patterns across time. Results from this study will help scientists understand lethal contests in animals, aggressive behavior, and the process of aging. Though loons are common within their range, they are considered of special concern by the Wisconsin Department of Natural Resources, and are declining across their range. Long-term data and results from this project will inform conservation and management programs. In addition, the project will train a large number of undergraduate students who, by initiating independent field projects, will learn about experimental design, data collection and statistical analysis. Discoveries about this popular bird will be shared with the broader public via popular articles, T.V. and radio interviews, and a project website.