State uncertainty models and mark‐resight models for understanding non‐breeding site use by Piping Plovers |
| |
| Authors: | Jonathan B Cohen Sidney B Maddock Melissa K Bimbi W Walker Golder Olivia E Ledee Francesca J Cuthbert Daniel H Catlin James D Fraser Cheri L Gratto‐Trevor |
| |
| Affiliation: | 1. Department of Environmental and Forest Biology, State University of New York College of Environmental Science and Forestry, Syracuse, NY, USA;2. Prairie and Northern Wildlife Research Centre, Science and Technology, Environment and Climate Change Canada, Saskatoon, SK, Canada;3. National Audubon Society, Buxton, NC, USA;4. U.S. Fish and Wildlife Service, South Carolina Field Office, Charleston, SC, USA;5. National Audubon Society, Wilmington, NC, USA;6. Department of Fisheries, Wildlife, and Conservation Biology, University of Minnesota, St. Paul, MN, USA;7. Department of Fish and Wildlife Conservation, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA |
| |
| Abstract: | Conservation of beach‐nesting medium‐distance migrants has focused on breeding areas because protection of nests is more tractable than protection of non‐breeding habitat. As breeding ground management has encountered diminishing returns, interest in understanding threats in non‐breeding areas has increased. However, robust estimates of non‐breeding demographic rates and abundance are generally lacking, hindering the study of limiting factors. Estimating such rates is made more difficult by complex population dynamics at non‐breeding sites. In South Carolina, endangered Piping Plovers Charadrius melodus start arriving in July and some depart prior to December (the autumn‐only population) while others remain through at least March (the wintering population). State uncertainty capture‐mark‐recapture models provide a means for estimating vital rates for such co‐occurring populations. We estimated the proportion of the population entering the study area per survey (entry probability) and proportion remaining per survey (persistence rate) for both populations during autumn, and abundance of the wintering population, at four sites in South Carolina in 2006/7 and 2007/8, taking advantage of birds previously colour‐ringed on the breeding grounds. We made fairly precise estimates of entry and persistence rates with small sample sizes. Cumulative entry probability was ~50% by the end of July and reached 95% for both populations by October. Estimated stopover duration for birds in the autumn‐only population was 35 days in year 1 and 42 days in year 2. We estimated a wintering super‐population size of 71 ± 16 se birds in the first year and 75 ± 16 in the second. If ringing programmes on the breeding grounds continue, standardized resighting surveys in the non‐breeding period and mark‐recapture models can provide robust estimates of entry and persistence rates and abundance. Habitat protection intended to benefit non‐breeding Piping Plovers at our coastal sites should be in effect by late summer, as many birds are resident from July to the end of winter. |
| |
| Keywords: |
Charadrius melodus
endangered species migration non‐breeding population estimation shorebirds survival |
|
|
