UVM Theses and Dissertations
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Print
Author:
Watrous, Kristen S.
Dept./Program:
Wildlife and Fisheries Biology Program
Year:
2006
Degree:
M.S.
Abstract:
Predicting potential habitat across a landscape is extremely challenging for rare species. Analyzing habitat requirements using partitioned Mahalanobis D² methods avoid pitfalls commonly encountered when surveying elusive species that typically have small sample sizes and low detection probabilities because it is based solely on data collected at known species locations. Minimum habitat requirements are determined by examining a principal components analysis to determine habitat characteristics that are consistent across known locations. The goals of this study were to (1) document and compare the minimum habitat requirements of Indiana bats (Myotis sodalis) in the Champlain Valley across 7 spatial scales and (2) map potential habitat for the species throughout the same area.
We radio-tracked 24 female Indiana bats to their roost trees and across their nighttime foraging areas, and collected habitat characteristics at 7 spatial scales: 1) roost trees, 2) 0.1 ha circular plots surrounding the roost trees, 3) home ranges, and 4-7) 0.5 km, 1 km, 2 krn, and 3 krn buffers surrounding the roost tree. Fifty roost trees were identified and found to be tall, large diameter trees with exfoliating bark, located typically at low elevations and close to water. Trees in the plots surrounding roost trees were typically smaller in dbh, shorter in height, and healthier than the central roost trees. Fourteen home ranges were found to be in areas of diverse, patchy land cover types that were close to water, with an east-facing aspect.
Across all landscape extents, the total area of forest within roost tree buffers and the aspect across those buffers were the two most consistent features. Predictive maps indicated that suitable habitat ranged from 4.7% to 8.1% of the total area examined depending upon the number of components used, and was distributed throughout the Champlain Valley. However, information is needed on birth and survival rates to assess habitat quality in the region.
We radio-tracked 24 female Indiana bats to their roost trees and across their nighttime foraging areas, and collected habitat characteristics at 7 spatial scales: 1) roost trees, 2) 0.1 ha circular plots surrounding the roost trees, 3) home ranges, and 4-7) 0.5 km, 1 km, 2 krn, and 3 krn buffers surrounding the roost tree. Fifty roost trees were identified and found to be tall, large diameter trees with exfoliating bark, located typically at low elevations and close to water. Trees in the plots surrounding roost trees were typically smaller in dbh, shorter in height, and healthier than the central roost trees. Fourteen home ranges were found to be in areas of diverse, patchy land cover types that were close to water, with an east-facing aspect.
Across all landscape extents, the total area of forest within roost tree buffers and the aspect across those buffers were the two most consistent features. Predictive maps indicated that suitable habitat ranged from 4.7% to 8.1% of the total area examined depending upon the number of components used, and was distributed throughout the Champlain Valley. However, information is needed on birth and survival rates to assess habitat quality in the region.