Behavioral Ecology Advance Access originally published online on August 4, 2008
Behavioral Ecology 2008 19(6):1235-1242; doi:10.1093/beheco/arn082
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Published by Oxford University Press 2008.
Multiple proximate and ultimate causes of natal dispersal in white-tailed deer
a Intercollege Graduate Degree Program in Ecology, Pennsylvania State University, University Park, PA 16802, USA b U.S. Geological Survey, Pennsylvania Cooperative Fish and Wildlife Research Unit, Pennsylvania State University, University Park, PA 16802, USA c Pennsylvania Game Commission, Bureau of Wildlife Management, Harrisburg, PA 17110, USA
Address correspondence to E.S. Long, who is now at Department of Biology 3307 3rd Avenue West, Suite 205, Seattle Pacific University, Seattle, WA 98119, USA. E-mail: longe{at}spu.edu.
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Abstract |
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Proximate and ultimate causes of dispersal in vertebrates vary, and relative importance of these causes is poorly understood. Among populations, inter- and intrasexual social cues for dispersal are thought to reduce inbreeding and local mate competition, respectively, and specific emigration cue may affect dispersal distance, such that inbreeding avoidance dispersal tends to be farther than dispersal to reduce local competition. To investigate potential occurrence of multiple proximate and ultimate causes of dispersal within populations, we radio-marked 363 juvenile male white-tailed deer (Odocoileus virginianus) in 2 study areas in Pennsylvania. Natal dispersal probability and distance were monitored over a 3-year period when large-scale management changes reduced density of adult females and increased density of adult males. Most dispersal (95–97%) occurred during two 12-week periods: spring, when yearling males still closely associate with related females, and prior to fall breeding season, when yearling males closely associate with other breeding-age males. Following changes to sex and age structure that reduced potential for inbreeding and increased potential for mate competition, annual dispersal probability did not change; however, probability of spring dispersal decreased, whereas probability of fall dispersal increased. Spring dispersal distances were greater than fall dispersal distances, suggesting that adaptive inbreeding avoidance dispersal requires greater distance than mate competition dispersal where opposite-sex relatives are philopatric and populations are not patchily distributed. Both inbreeding avoidance and mate competition are important ultimate causes of dispersal of white-tailed deer, but ultimate motivations for dispersal are proximately cued by different social mechanisms and elicit different responses in dispersers.
Key words: demography, dispersal probability, dispersal rate, proximate cause, sex-biased dispersal, sociobiology.
Received 7 September 2007; revised 6 June 2008; accepted 23 June 2008.