UVM Theses and Dissertations
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Print
Author:
Freeman, Mark
Dept./Program:
Wildlife and Fisheries Biology Program
Year:
2010
Degree:
M.S.
Abstract:
Species with large home ranges often include many different habitat classes. Identifying key habitats and resource used by these species has been an ongoing challenge for wildlife professionals for many decades. In the state ofVermont, the bobcat (Lynx rufus) is an example of a wide-ranging species that is also of great conservation concern. To quantify home range requirements ofthis species, we captured and collared 14 bobcats across a landscape gradient that ranged from urbanized settings to forested settings. Bobcats were outfitted with store-on-board GPS collars that collected spatially explicit locations from individual cats every four hours for 3-4 months. We used kernel home range techniques to estimate home range size and boundaries, and to quantify the utilization distribution (lID), which is a spatially explicit mapping of how different areas within the home range are used.
Male home ranges averaged 71 km² while female home ranges averaged 22.9 km². We then used GIS methods to quantify both biotic (e.g. habitat types, stream density) and abiotic (e.g. ledge habitat) associated with each bobcat's home range and within a 500 meter buffer surrounding the home range. Paired t-tests identified agriculture as the only area type with significant differences (t = -2.71, df= 13, P = 0.018); on average, 25% ofthe area in the buffer was classified as agriculture versus 36% in the home range. We used Akaike's Information Criterion (AIC) to rank our model set (N-27) for all 14 bobcats. The Habitat 1km Components model was the top ranked model for 10 of our 14 bobcats.
Eight of the 10 bobcats showed increased use of shrub and 9 for wetland classifications with increased quantities of these resources. In addition 2 more bobcats selected the Roads lkm as their top model while 2 other bobcats selected the Fisher 1km and Forest Edge 90m models as their top models. Habitat requirements were then then determined to map potential population wide quality habitat state wide. On average, bobcat home ranges consisted of 64% bobcat habitat (all forest types, scrubshrub, andwetland), or 14.7km² of habitat of the female'shome range. Adult female bobcats maintain exclusive home ranges, so we thereby estimated that Vermont could support a breeding female population of 987 females.
Male home ranges averaged 71 km² while female home ranges averaged 22.9 km². We then used GIS methods to quantify both biotic (e.g. habitat types, stream density) and abiotic (e.g. ledge habitat) associated with each bobcat's home range and within a 500 meter buffer surrounding the home range. Paired t-tests identified agriculture as the only area type with significant differences (t = -2.71, df= 13, P = 0.018); on average, 25% ofthe area in the buffer was classified as agriculture versus 36% in the home range. We used Akaike's Information Criterion (AIC) to rank our model set (N-27) for all 14 bobcats. The Habitat 1km Components model was the top ranked model for 10 of our 14 bobcats.
Eight of the 10 bobcats showed increased use of shrub and 9 for wetland classifications with increased quantities of these resources. In addition 2 more bobcats selected the Roads lkm as their top model while 2 other bobcats selected the Fisher 1km and Forest Edge 90m models as their top models. Habitat requirements were then then determined to map potential population wide quality habitat state wide. On average, bobcat home ranges consisted of 64% bobcat habitat (all forest types, scrubshrub, andwetland), or 14.7km² of habitat of the female'shome range. Adult female bobcats maintain exclusive home ranges, so we thereby estimated that Vermont could support a breeding female population of 987 females.