Literaturdatenbank
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Erb, L., & Willey, L. , Detecting long-term population trends for the eastern box turtle (terrapene c. carolina) in massachusetts.
Added by: Admin (06 Jan 2014 18:22:46 UTC) |
| Resource type: Conference Paper BibTeX citation key: Erb2011a View all bibliographic details  |
Categories: General Keywords: Habitat - habitat, Nordamerika - North America, Schildkröten - turtles + tortoises Creators: Erb, Willey |
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| Abstract |
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The probability of patch occupancy has been suggested as a potential state variable for longterm, large-scale monitoring programs even when the probability of detection is <1 and abundance varies between sites. These models are particularly useful for rare or elusive species that are difficult to detect, as is the case with many rare reptiles. We designed an occupancybased monitoring program for the eastern box turtle in Massachusetts, where they are a Species of Special Concern. Conservation Areas were designated in a statewide conservation plan for the species. Sixty sampling plots, four ha in size, were identified for sampling within these box turtle conservation areas. Plots were placed within early successional habitat and along forest edge habitat, locations where turtles gather to nest, so that sampling can occur during the nesting season. Sampling plots were stratified by region within the state and plans are to randomly sample these plots once every two years to track population trends. In addition, sites will be sampled three times within a single season once every five years to estimate the probability of detection. Model assessment using these preliminary data suggests several occupancy models are equally good at estimating occupancy, including the Royle/Nichols model. At our sampling sites, this model predicted a probability of box turtle occupancy of 0.82 and a probability of detection of 0.35. A power analysis indicates that we will be able to detect a -5% yearly population trend in approximately 18 years and a -3% trend in 25 years.
Added by: Admin |