Search

Many species show natal habitat preference induction (NHPI), a behavior in which young adults select habitats similar to those in which they were raised. However, we know little about how NHPI develops in natural systems. Here, we tested for NHPI in juvenile common loons (Gavia immer) that foraged on lakes in the vicinity of their natal lake after fledging. Juveniles visited lakes similar in pH to their natal lakes, and this significant effect persisted after controlling for spatial autocorrelation. On the other hand, juveniles showed no preference for foraging lakes of similar size to their natal one. When lakes were assigned to discrete classes based on size, depth, visibility, and trophic complexity, both juveniles from large lakes and small lakes preferred to visit large, trophically diverse lakes, which contained abundant food. Our results contrast with earlier findings, which show strict preference for lakes similar in size to the natal lake among young adults seeking to settle on a breeding lake. We suggest that NHPI is relaxed for juveniles, presumably because they select lakes that optimize short-term survival and growth. By characterizing NHPI during a poorly studied life stage, this study illustrates that NHPI can take different forms at different life stages.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2007.10.025 Byline: Walter H. Piper, Charles Walcott, John N. Mager, Frank J. Spilker Abstract: Theoretical models predict that lethal contests should take place only when animals have severely limited breeding opportunities. Indeed, fatal fighting appears to occur routinely in only a handful of species that fit this mould. Here we report that 16-33% of all territorial evictions in male common loons, Gavia immer, are fatal for the displaced owner; in contrast, females seldom fight to the death for territories despite frequent territorial evictions. Since loons are long-lived and have ample reproductive options, they differ starkly from other fatal-fighting species. Several factors might contribute to lethal combat in loons, including: (1) the high value of territories to males, (2) a steady loss of condition among male residents, which could lead individuals with poor reproductive prospects to invest heavily in a current reproductive attempt, and (3) an inability of males defending tiny lakes to escape aggressive usurpers, owing to extremely high wing loading. The difficulty of detecting fatal contests in the field and the tendency of scientists to underestimate the behavioural impact of rare events leave open the possibility that fatal contests are a more widespread behavioural pattern than currently thought. Author Affiliation: (a) Department of Biological Sciences, Chapman University, U.S.A. (a ) Department of Neurobiology and Behavior, Cornell University, U.S.A. (a ) Pamlico River Drive, Washington, NC, U.S.A. Article History: Received 14 March 2007; Revised 30 April 2007; Accepted 17 October 2007 Article Note: (miscellaneous) MS. number: A10720R

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2006.10.009 Byline: John N. Mager, Charles Walcott, Walter H. Piper Abstract: We investigated whether male-specific territorial 'yodels' communicate information about individual size and condition in the common loon. Individuals in better condition and of larger body mass, but not larger structural body size, produced lower-frequency yodels, and changes in dominant frequencies of yodels between years reflected changes in male body mass and condition. An acoustic playback experiment indicated that potential receivers vocalized sooner and more often in response to low-frequency yodels, a possible indication that dominant frequencies of the yodel may communicate condition-dependent fighting abilities. Physiological constraints associated with mass and/or condition may preserve honest signalling by preventing small individuals from producing low-frequency yodels. Author Affiliation: (a) Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, U.S.A. (a ) Department of Biological Sciences, Chapman University, Orange, CA, U.S.A. Article History: Received 24 March 2006; Revised 5 May 2006; Accepted 4 October 2006 Article Note: (miscellaneous) MS. number: A10401R