Master's Theses

Document Type

Thesis

Date of Award

Spring 2013

Degree Name

Master of Science (MS)

Department

Biology

Advisor

Dr. Elmer J. Finck

Abstract

The eastern spotted skunk (Spilogale putorius) is a small omnivorous Carnivora similar in much of its natural history to the commonly found striped skunk (Mephitis mephitis). Spilogale putorius has experienced drastic population declines over a large portion of its geographic range. Many hypotheses for the decline of S. putorius have been proposed. δ13C and δ15N isotope analysis provides a unique opportunity to examine diet over an expanded time span. Thus was used on hair sampled from natural history collections, teaching collections, and road kills to examine dietary change for both S. putorius and M. mephitis from 1852 to 2012. Because stable isotope values of hair reflect the diet at the time the hair was grown, knowledge of molting patters is necessary when using hair in stable isotope studies. I determined molting patterns in S. putorius were similar to M. mephitis. When compared to M. mephitis molting patterns in S. putorius were delayed by approximately a month. Long-term farm and crop trends have not been examined in Kansas. I examined trends in average farm size, percent of land in farms, number of farms, number of irrigated farms, hectares of woodland, and hectares of17 different crops across Kansas from 1880 to 2007. Trends were observed in most crop types and provided support for a slow transition from small diversely planted farms to large scale monoculture in Kansas. I analyzed Kansas fur harvest trends for M. mephitis and S. putorius and detected corresponding declines in Kansas for both species. These declines were correlated with a reduction of maize in the landscape and agricultural intensification. Studies indicate the presence of melanin in colored feathers affects the δ13C and δ15N values of feather samples. I examined the effect of melanin on δ13C and δ15N values of hair from 8 mammal species but detected no effect. The effects of preservation techniques on δ13C and δ15N values of mammalian samples are also not well understood. I examined the effect of tanning as a preparation technique on δ13C and δ15N values of M. mephitis. Tanned hides were depleted in both stable isotopes compared to non-tanned hides. Diet of S. putorius and M. mephitis was related to landscape structure. Maize composed the highest proportion of the diet for both S. putorius and M. mephitis and has experienced change in the diet of S. putorius over time. In addition, increased δ15N variability was observed over time in these species, potentially suggesting decline of or exclusion from historical diet sources. This research provided useful insights into the effects of landscape structure on a declining mesocarnivore, and provided additional support for dietary change as a contributing factor to the decline of S. putorius. When combined, these data potentially provide evidence for a decline in S. putorius based in part on a reduction in the amount of maize in the landscape and agricultural intensification.

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© 2013 Amanda E. Cheeseman

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