Effect of Abundance and Survey Protocol on Estimates of Occupancy and Detection Probability for Northern Bobwhites

Abstract

We compared estimates of occupancy of northern bobwhite (Colinus virginianus) between areas with relatively low and high abundance using single-survey and multiple-survey protocols, with and without accounting for detection probability, and investigated how time during the breeding season affected detection probability in Oklahoma, USA, in 2009–2011. Estimates of occupancy and detection probability increased as the number of survey occasions increased. Detection probability was significantly higher in the area of high abundance (P 0.001), and increased as the breeding season advanced from mid-May to late July. Accounting for detection probability increased occupancy estimates by 31% in the low-abundance area but only 1.9% in the high abundance area when using 3 survey occasions per year. Managers using occupancy to detect changes in bobwhite populations should use 4 survey occasions per year to ensure accurate estimates of both occupancy and detection probability.