Thesis (M.S.)--Brigham Young University. Dept. of Integrative Biology, 2006. / Includes bibliographical references (p. 27-34).

We tested the adequacy of standard 30 m riparian buffers for semi-aquatic vertebrate species, using the boreal toad (Bufo boreas boreas) as an example. We monitored toad populations in south-central Utah using radio telemetry during the summers of 2003 and 2004. We found 30 m buffers inadequate for protecting boreal toads and suggest this is likely true for other species as well. Managers must consider several factors when constructing buffers: (1) Buffer requirements may vary by time of year. While we located toads most often in wet habitats, toads commonly utilized upland habitats in late summer, occasionally at distances greater than 100 m from water. (2) A single year's observation may not be sufficient to establish adequate buffers. Toads moved into upland habitats more often and at greater distances from water (> or = 30 m) during the wetter, cooler weather conditions of 2004 than in 2003. (3) Buffer requirements may differ by sex. Male toads appeared to have stronger selection for wetland habitats than females. Females moved greater distances from water than males, often outside of buffer areas. (4) Buffer requirements may differ by location. 30 m buffers contained 82.4% of all observations, though results varied between 50.0 and 97.2%, depending on breeding location. Finally (5) All habitat requirements should be considered when establishing buffers. Many small, unmapped streams and seeps utilized by toads for hibernation were located outside buffer zones. After ground truthing and extending 30 m buffers around these habitats, the percentage of all observations within 30 m buffers increased to 92.4%. Managers need to be aware of the accuracy of digital and other mapping sources used in creating buffers and to incorporated all critical habitats in conservation buffers. Our boreal toad example suggests that ground truthing may be the most important factor in establishing effective buffer zones.

The western toad (Anaxyrus boreas, formerly Bufo boreas) is one of many amphibian species considered to be at risk of extinction (COSEWIC status is Special Concern). I examined habitat use patterns of the western toad using several methods to gain a better understanding of its habitat requirements. I examined the relationship between relative abundance of the western toad and two sympatric amphibian species (wood frog, Lithobates sylvaticus; and boreal chorus frog, Pseudacris maculata) and habitat features at eight scales of spatial extent at 24 wetlands in the Lake Utikuma region of Alberta, Canada. I radio-tracked adult western toads in three study areas in the Aspen Parkland and Boreal regions of north-central Alberta to examine 1) whether patterns of habitat selection change with different scales of spatial extent, spatial resolution, habitat composition, temporal period, and between males and females during the active period, 2) habitat used for hibernation, and 3) factors influencing the timing and nature of movements to hibernation sites. I found that the abundance of the three amphibian species was best described at different spatial extents and was related to the biology of each species. Resource Selection Function (RSF) models, created using radio-telemetry data, indicated that habitat selection was scale-dependent for western toads; differences in selection were observed among study designs, study areas, time periods, and sexes. Predictive ability did not differ significantly among study designs. However, models that were created using a fine-grained map and home-range spatial extent generally produced models with greater predictive ability than models using a coarse-grained map or population-range extent. During the active season toads selected open habitat types such as wet shrub, disturbed grass, and crop/hay fields. Western toads hibernated terrestrially in pre-existing tunnels and the majority of toads hibernated in forest stands dominated by spruce. Toads used hibernation sites 1461936 m from breeding ponds and 68% of hibernacula were communal. Arrival at and entry into hibernation sites was influenced by temperature and/or day length; larger toads moved to hibernation sites later in the year. My research results can be used to identify and protect habitat for western toads in Canada. / Environmental Biology and Ecology

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