Population trends and calling phenology of anuran populations surveyed in Ontario estimated using acoustic surveys |
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Authors: | Shane R. de Solla Kim J. Fernie Glenn C. Barrett Christine A. Bishop |
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Affiliation: | (1) Canada Centre for Inland Waters, Canadian Wildlife Service, Environment Canada, 867 Lakeshore Road, P.O. Box 5050, L7R 4A6 Burlington, Ont., Canada;(2) Canadian Wildlife Service, Environment Canada, 5421 Robertson Road, V4K 3N2 Delta, BC, Canada |
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Abstract: | Many acoustic surveys have been initiated to monitor anuran populations in North America. We used the Ontario Backyard Frog Survey to examine temporal and spatial trends, from 1994 to 2001. Our data suggest that there have been no consistent trends in site occupancy during this time period, but there were some differences among years. Both American toads and northern leopard frogs were more prevalent in 1995 than in 1994. Similarly, species richness was higher in 1995 and 1996 compared to most other years. Individual populations of species, however, often were not stable. Extinction and colonization rates varied among species, and ranged from 1.5 to 19.5% per year, and site occupancy was negatively correlated with extinction rates. Daily detection probabilities were often quite low, and were primarily driven by the perceived calling intensity. We recommend: (i) that monitoring programs attempt to preserve common survey routes, despite heavy turnover of volunteers, (ii) calling surveys be timed to maximize detection probabilities, and (iii) analyses based upon landscape features and GIS approaches should be used to determine localized changes in site occupancy or species richness. |
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Keywords: | Amphibian decline Conservation Detection probability Monitoring |
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