Within the Omaha metropolitan area of Nebraska, melanistic fox squirrels (Sciurus niger) have expanded westward and increased in frequency. The selective advantage of melanism is currently unknown; therefore, I assessed overwinter body condition and skin temperature as potential factors for a selective advantage in melanistic fox squirrels. Also, I assessed seasonal behavior for behaviors or patterns that may be allowing melanistic fox squirrels to expand in this area. Overwinter body measurements, skin temperatures, and seasonal behavioral observations were collected and compared between melanistic and rufus fox squirrels. Significant differences were detected between melanisic and rufus fox squirrel pre-winter body condition, and rufus fox squirrel pre- and post-winter body condition. There were no significant differences between melanistic and rufus fox squirrel post-winter body conditions, and melanistic fox squirrel pre- and post-winter body conditions. Skin temperatures of rufus fox squirrels differed with sun exposure; individuals in full sun had the highest skin temperatures followed by individuals in shady and cloudy conditions. Unlike rufus fox squirrels, skin temperatures of melanistic fox squirrels did not differ with respect to sun exposure. Seasonal behaviors of melanistic and rufus fox squirrels were significantly different between seasons; however, this was due to the high number of behaviors observed rather than any meaningful biological reason. Across all seasons, melanistic and rufus fox squirrels allocated the most time to locomotion and feeding. In summer, melanistic squirrels did more locomotion while rufus squirrels did more feeding. In winter, this pattern was reversed with melanistic squirrels feeding more and rufus squirrels doing more locomotion. In a behavior sequence, fox squirrels were most likely to transition into locomotion behaviors, while reproductive behaviors were transitioned into the least. My results indicate that melanistic fox squirrels may have a thermal advantage over rufus fox squirrels not because of their body condition, but due to individuals maintaining skin temperatures the same at different levels of sun exposure. Significant differences detected between melanistic and rufus fox squirrel seasonal behavior do not necessarily suggest that melanistic individuals perform behaviors or patterns supportive of their westward expansion.
|Advisor:||Wilson, James A.|
|Commitee:||French, Jeffrey A., White, Jeremy A., Wilson, James A.|
|School:||University of Nebraska at Omaha|
|School Location:||United States -- Nebraska|
|Source:||MAI 53/05M(E), Masters Abstracts International|
|Keywords:||Behavior, Body condition, Melanism, Nebraska, Sciurus niger, Skin temperature|
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