Date of Award

Spring 2000

Document Type

Thesis

Department

Life & Environmental Sciences

First Advisor

Grant Hokit

Second Advisor

Jack Oberweiser

Third Advisor

Joan Stottlemyer

Abstract

The populations of many amphibian species appear to be in decline. The loss of amphibians contributes to the overall loss of biodiversity that is occurring on a global scale. Amphibians are well-known bioindicators and can perhaps aid in # pinpointing factors responsible for the loss of biodiversity. Habitat patch size is a crucial variable to species persistence. I examined the relationship between wetland area and population occupancy for three amphibian species of the Western Montana Rockies: Ambystoma macrodactylum (long-toed salamander), Bufo boreas (Western toad), and Rana luteiventris (spotted frog). A logistic regression analysis revealed significant associations between increasing wetland area and breeding activity for spotted frogs and long-toed salamanders. I observed a threshold wetland area required to sustain breeding populations, and suggest that this minimum area is essential for amphibian persistence. Although a significant association was not observed for Western toads, this absence was most likely due to small sample size.

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