Examination of Potentially Ectoparasite-driven Behavior in Burrowing Owls: Tests of Alternative Hypotheses
Thu, 05/07/2015 - 19:06
Abstract: Burrowing Owls (Athene cunicularia) and their nests harbor at least 39 species of arthropods from 21 different families. Among the ectoparasites on Burrowing Owls are fleas, which are primarily Pulex irritans (Family Pulicidae), the human flea. Fleas can number in the hundreds on individual Burrowing Owls. Thus, we hypothesized that flea infestation has shaped Burrowing Owl behavior to avoid the costs of ectoparasitism. As part of experiments using infrared trail cameras deployed at Burrowing Owl nests in southern Idaho ¬¬during 2012-2013, we noticed apparent sunning behavior in both adult and nestling Burrowing Owls. Camera images captured owls lying on the ground with wings outstretched and flat. We only observed this behavior during daylight hours, although cameras were active for 24 h/day. Sunbathing in birds is often associated with ectoparasite reduction, although sunning has not previously been examined in relation to flea infestation. During 2014 we conducted an experiment that included fumigating some nests with a flea removing insecticide and examined the prediction that sunbathing would occur more frequently in control nests where ectoparasites remained. As sunning was not during the coolest parts of the day, it did not appear to function for warming. Also, we ultimately found no difference in the frequency of sunning in fumigated and control nests, and there was no relationship between sunning and abundance of fleas on owls. Thus, the evidence is not consistent with the ectoparasite hypothesis, as owls sunned irrespective of flea load. We also evaluated the alternative hypotheses that sunning was related to thermoregulation, anting, drying or feather degrading bacteria. The first three we were able to reject, and the last will need future research.
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White-tailed Deer Browse Preference: A Comparative Study of the Catskill and Adirondack Mountain Regions, New York State
Tue, 05/05/2015 - 14:23
Abstract: Abundant white-tailed deer (Odocoileus virginianus) in New York State, United States, affect forest regeneration and stand composition through feeding (browse) pressure. White-tailed deer browse preference of six different hardwood tree species in two mountain ranges, the Catskill and Adirondack Mountains, within New York State were compared in order to determine the extent of browse selection by deer. There were no statistically different browse selection by white-tailed deer within the Catskills or Adirondack study area or between each study site. Visual analysis of the study areas after concluding the study revealed that red maple (Acer rubrum) was the preferred browse species at each study site.
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Major: Biology, Natural Resources Management and Policy