Date of Award

Fall 12-1-2007

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

William A. Mitchell

Second Advisor

Steven L. Lima

Third Advisor

Peter E. Scott

Abstract

I studied the effect of environmental conditions on the foraging behavior of Carolina chickadees (Poecile carolinensis) in Kiewig woods, property of Indiana State University, in West Terre Haute in west-central Indiana. My study method uses Optimal Foraging Theory (Brown 1988) to measure the giving up density (GUD) of Chickadees under different environmental conditions ( different resource abundances, different habitat types, different resource types and different seasons). For my experiment, I set up 24 feeding stations in three kinds of habitats ( open area, secondary growth woods and mature woods) within 4 sites and paired trays in each habitat X site. During the period from August 2006 through May 2007, I collected different kinds of data based on my experimental design. My results show that Carolina chickadees used a variable search time strategy when foraging, indicating that they have ability to assess resource quality in food patches. However, they are not omniscient regarding the quality of the food patch, so while they show positive density dependence harvesting rate, they nonetheless under-exploit rich patches. Furthermore, Chickadees change foraging behavior depending on environmental conditions. On average, the foraging cost of Carolina chickadees as measured by GUDs is higher in summer than in winter. During summer, birds left higher GUDs in open area, but similar GUDs in open and wooded habitat during winter; the leaves falling reduce coverage of canopy in the woods increase predation risk in woods might be a reason. In both winter and summer, Chickadees had lower GUDs on mealworms than seeds, indicating that mealworms are more valuable food than seeds on a per weight basis. This preference for mealworms was significantly stronger during summer (breeding season).

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