Birds
Animal Behavior
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• Two outdoor aviaries for studies of avian social behavior
• Equipment for field research with wild birds, such as mist nets, radio telemetry receivers, and video cameras
• Video playback equipment for detailed behavioral analyses of video recordings
• Molecular zoology lab equipped to use DNA markers for quantifying relatedness between individuals, assaying the genetic structure of populations, and identifying the gender of sexually monomorphic birds
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Faculty Interests – Donald C. Dearborn
My research interests fall under the general headings of behavioral ecology and conservation biology, with an emphasis on mating systems, brood parasitism, demography, and life history evolution. In each of these areas, I focus on the fitness consequences of social interactions among animals and the manner in which those fitness consequences can affect both evolution in natural populations and strategies for successful conservation. Current projects include:
• The Mating System of Great Frigatebirds
Frigatebirds are characterized by the unusual combination of extreme sexual dimorphism and balanced parental effort by males and females. Biparental care is a highly conserved ancestral trait found in seabirds and their relatives, but sexual dimorphism is a recently derived trait found in all 5 species of frigatebirds but in none of the other 250+ species in their clade. Much of my work with frigatebirds has centered on the features that set them apart from "typical" seabirds—extreme male ornaments, lek-like mate choice, short-term pair bonds, and potentially heightened conflict over parental effort.
• Brood Parasitism
To date, my work with brood parasites has focused on nestling behavior in the brown-headed cowbird, an obligate brood parasite that lays eggs in the nests of other species. However, I also plan to start a project with the yellow-billed cuckoo, a North American cuckoo that, unlike its Old World relatives, lays parasitic eggs only facultatively. The costs, benefits, and circumstances that prompt such behavior are unknown. One fundamental issue is whether an individual bird (1) spends its reproductive effort strictly on one mode or the other (i.e. parasitic or parental), or (2) adopts some sort of conditional strategy, laying parasitically under some circumstances and engaging in parental care under others.
• Cooperation and Conflict Between Mates
Alliances for the purpose of reproduction are frequently characterized by conflict and manipulation, in which each individual is trying to maximize its own reproductive success while minimizing the associated costs. The dynamic of the parental effort decisions by mated birds is an area ripe for additional study. One topic that particularly intrigues me is the potential for an individual to exhibit "retaliatory" behavior in response to low parental effort by its mate. In the future, I hope to build on my work with frigatebirds and explore some of these ideas with a population of song sparrows at the Bucknell Natural Area.
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*Juola FA, and Dearborn DC. Does the differential cost of sons and daughters lead to sex ratio adjustment in great frigatebirds (Fregata minor)? In Press. Journal of Avian Biology.
Dearborn DC, Anders AD, and Williams JB. 2005. Courtship display by great frigatebirds, Fregata minor: an energetically costly handicap signal? Behavioral Ecology and Sociobiology 58: 397-406.
*Cohen LB and Dearborn DC. 2004. Begging and short-term need in cowbird nestlings: how different are brood parasites? Behavioral Ecology and Sociobiology 56(4): 352-359
* denotes Animal Behavior student/alumnus
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· Climate, food, and reproductive success of Alaskan seabirds (Alexis Will, '06)
· Sexual selection and the exhaustion of between-male variation in ornaments (Stephanie Wright, '06)
