Browsing UA Faculty Research by Journal
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Abundance and Density of a Columbian Black-Tailed Deer Population on an Urban IslandMethods to estimate abundance and density of Columbian black-tailed deer (Odocoileus hemionus columbianus) are limited. Regional wildlife managers are concerned that Columbian black-tailed deer on Whidbey Island, Washington, USA, exceed carrying capacity. Research on small islands in the Pacific Northwest reports high deer densities; however, these islands are smaller and less complex than Whidbey Island, and have fewer mortality sources. Our objective was to estimate the abundance and density of Columbian black-tailed deer on Whidbey Island by using road-based spotlight surveys in a distance sampling framework. We conducted spotlight surveys from 12 January 2015 to 23 January 2015 starting ≤1 h after sunset and continuing to 23:00. The deer population of Whidbey Island is estimated to be 2744.5 individuals (6.2 deer/km2), lower than estimated densities of deer on smaller islands in the region. Density varied across the different sections of Whidbey Island. Road-based spotlight surveys in a distance sampling framework are a useful tool for estimating deer populations in regions where traditional monitoring methods are not practical. This research offers baseline estimates for the deer on Whidbey Island and provides a repeatable procedure to estimate abundance and density.
Observations of Foothill Yellow-Legged Frog Predation by a Native Frog, Snake, and Giant Water Bug in a Central California Intermittent StreamDuring the summers of 2015 and 2018, we observed predation on Foothill Yellow-legged Frogs (Rana boylii) by a giant water bug (Abedus indentatus), a California Red-legged Frog (Rana draytonii), and a Diablo Range Gartersnake (Thamnophis atratus zaxanthus) adjacent to 3 separate isolated pools along intermittent reaches of Coyote Creek, Santa Clara County, California, USA. To the best of our knowledge, our observations provide the first published record of California Red-legged Frog and giant water bug preying upon Foothill Yellow-legged Frogs. As pool habitat contracts over the course of the dry season, locally abundant Yellow-legged Frogs may be increasingly vulnerable to predation from a suite of aquatic and terrestrial predators.