A winter distribution model for Bicknell's Thrush (Catharus bicknelli), a conservation tool for a threatened migratory songbird

PLoS One. 2013;8(1):e53986. doi: 10.1371/journal.pone.0053986. Epub 2013 Jan 9.

Abstract

Conservation planning and implementation require identifying pertinent habitats and locations where protection and management may improve viability of targeted species. The winter range of Bicknell's Thrush (Catharus bicknelli), a threatened Nearctic-Neotropical migratory songbird, is restricted to the Greater Antilles. We analyzed winter records from the mid-1970s to 2009 to quantitatively evaluate winter distribution and habitat selection. Additionally, we conducted targeted surveys in Jamaica (n = 433), Cuba (n = 363), Dominican Republic (n = 1,000), Haiti (n = 131) and Puerto Rico (n = 242) yielding 179 sites with thrush presence. We modeled Bicknell's Thrush winter habitat selection and distribution in the Greater Antilles in Maxent version 3.3.1. using environmental predictors represented in 30 arc second study area rasters. These included nine landform, land cover and climatic variables that were thought a priori to have potentially high predictive power. We used the average training gain from ten model runs to select the best subset of predictors. Total winter precipitation, aspect and land cover, particularly broadleaf forests, emerged as important variables. A five-variable model that contained land cover, winter precipitation, aspect, slope, and elevation was the most parsimonious and not significantly different than the models with more variables. We used the best fitting model to depict potential winter habitat. Using the 10 percentile threshold (>0.25), we estimated winter habitat to cover 33,170 km(2), nearly 10% of the study area. The Dominican Republic contained half of all potential habitat (51%), followed by Cuba (15.1%), Jamaica (13.5%), Haiti (10.6%), and Puerto Rico (9.9%). Nearly one-third of the range was found to be in protected areas. By providing the first detailed predictive map of Bicknell's Thrush winter distribution, our study provides a useful tool to prioritize and direct conservation planning for this and other wet, broadleaf forest specialists in the Greater Antilles.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animal Migration / physiology*
  • Animals
  • Climate
  • Conservation of Natural Resources*
  • Cuba
  • Dominican Republic
  • Ecosystem
  • Environmental Monitoring
  • Haiti
  • Jamaica
  • Puerto Rico
  • Seasons
  • Songbirds / physiology*

Grants and funding

The authors gratefully acknowledge funding support over the many years of this study from the Carolyn Foundation, the Charles Blake Fund of the Nuttall Ornithological Club, the Conservation and Research Foundation, the National Fish and Wildlife Foundation, the National Geographic Society Committee for Research and Exploration, The Nature Conservancy, the Stewart Foundation, the Thomas Marshall Foundation, the United States Fish and Wildlife Service, the United States Department of Agriculture Forest Service Office of International Programs, and the Wildlife Conservation Society. Additional funding was provided by friends of the Vermont Center for Ecostudies and the Vermont Institute of Natural Science. Field work in Cuba was financially supported by Environment Canada and its Latin-America Program. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.