Reducing Effort When Monitoring Shorebird Productivity

Abstract

While several methods have been employed to estimate shorebird abundance and productivity, little attention has been given to differences in methods used to collect these data. Within central North America, Interior Least Tern (Sternula antillarum athalassos; hereafter, Least Tern) and Piping Plover (Charadrius melodus) monitoring is often accomplished through surveys from a distance or within the nesting colony. Four years (2013-2016) of season-long monitoring (April- mid-September) were implemented from inside and outside nesting colonies at off-channel nesting sites along the central Platte River, Nebraska, USA to compare estimates of resulting productivity components. Each method was found to have observational strengths and weaknesses, depending on the species and reproductive component. Outside Least Tern monitoring resulted in higher fledgling counts (256 total fledglings) and lower breeding pair estimates (242 total pairs), resulting in higher fledge ratios compared to inside monitoring (192 total fledglings, 261 total pairs). Differences in Piping Plover fledge ratios were annually variable (total pairs: inside estimate = 116, outside estimate = 103; total fledglings: inside estimate = 142, outside estimate = 117). Overall, both inside and outside monitoring can produce reasonable estimates of species abundance and productivity despite substantial differences in monitoring effort and cost.