US-Sweden Cooperative Science: Origin of Polygyny in a Polyterritorial System

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This award will support collaborative research in avian behavioral ecology between Dr. William Searcy, University of Pittsburgh and Dr. Arne Lundberg, Department of Zoology, Uppsala University, Sweden. The objective of the proposed research is the collection and analysis of critical field data on the well-studied polyterritorial and polygynous pied flycatcher. The investigators propose to examine the adaptive basis of polygyny in this species, in which polygyny is closely associated with the defense of multiple territories by single males (polyterritoriality). Female pied flycatchers pay a fitness cost if they choose an already-mated male, and they are not compensated for this cost by receiving a better territory or mate. One current hypothesis on why females nevertheless do mate polygynously is that the polyterritorial system allows males to deceive females about their mating status. A second hypothesis is that females choose mated males despite being aware of the male's true mating status, because of the high cost of continuing to search for an unmated male. The investigators plan to test the first hypothesis by determining whether there are reliable differences in behavior between mated and unmated males during periods when unmated females are observing them. If such differences exist, females ought to be able to determine male mating status. The second hypothesis will be tested by determining whether females that ultimately settle with mated males have previously encountered unmated males. Both tests will be performed by following the mate search of individually marked females forced to search for new mates by the removal of their previous mate and nestbox. The project will benefit from the combined experimental expertise of Dr. Searcy and Dr. Lundberg's record of productive field work with this species. The results of this research will make an important contribution to the field of behavioral ecology.