Heath, K.M., W.C. Conway, C.W. Boal, D.P., Collins, G. Hensley, W.P. Johnson, and P.M. Schmidt. 2021. Detectability and abundance of snowy plovers at the Salt Plains National Wildlife Refuge, Oklahoma. J. Fish and Wildlife Management 12:50-60.
Abstract
Abstract In the past two decades, Salt Plains National Wildlife Refuge (NWR) has been increasingly recognized as important habitat for both breeding and migratory shorebirds. Snowy plovers (Charadrius nivosus) in particular rely on the nearly 5,000 ha salt flat at Salt Plains NWR, which thousands use as breeding and stopover habitat. Elsewhere on the Southern Great Plains (SGP), decadal declines up to 75% within snowy plover subpopulations have been documented and attributed to vegetation encroachment, increased rates of nest predation, and decreased availability of fresh surface water. Despite many attempts to estimate this species’ abundance across the continent, to date, no known attempt at distance sampling of snowy plovers has occurred. To address this paucity of data, this study was designed to assess feasibility of distance sampling methods to accurately estimate snowy plover abundance and to determine their detectability. Distance sampling surveys (2017-2018) indicated high detection probability (P = 0.81) and the population abundance estimate across the salt flat extrapolated to 3,246 individuals. The distance sampling population abundance estimate is lower than population abundance estimates determined by Thomas et al. (2012) and the 2013-2017 refuge annual surveys (Hensley et al. unpublished data), but far greater than 2,105 estimated for the entire Great Plains (Morrison et al. 2006). Overall, distance sampling snowy plovers at Salt Plains NWR proved to be an effective addition to pre-established survey protocols but further investigation is needed to compare accuracy and precision of methods used in this study, annual surveys conducted by the refuge, and other potential snowy plover surveys.