Segregation of Male and Female Vespertilionid Bats by Elevation on the Olympic Peninsula, Washington

Bickford, Elizabeth

It is proposed that bats in western Washington are distributed along an elevational gradient with males and non-reproductive females occupying the higher elevation sites (between 800 and 1300 meters above sea level) and reproductive females occupying the lower elevation sites (below 150 meters above sea level). To test this assumption I performed a field study in the Olympic National Park using Tuttle traps and mist nets to live capture and identify bats to species and determine sex. Little is known about the species on the Olympic Peninsula due to the lack of previous studies. This study is part of a larger study funded by the National Parks Service. The objective of the overall study was to verify a bat species list within the park. Four study areas were used with four trap sites in each and they were open for four nights each. Traps were checked in the morning and data from collected bats was recorded. An insufficient number of bats of any species were trapped in the high elevation sites to test the data statistically for the original hypothesis. Instead, data were statistically analyzed to test the hypotheses that there are an equal number of bats of each species on the west side as the east and that species richness is the same from the west to the east side. Neither hypothesis was rejected.