Correlation of direct field observations of the endangered Golden Cheeked Warbler (Dendroica chrysoparia) with long-term acoustical measurements

Abstract

We present elements of a bioacoustics study that correlated direct field observations of the endangered Golden Cheeked Warbler (Dendroica chrysoparia) in the Balcones Canyonlands Preserve near Austin, TX with co-located long-term acoustical measurements. The goal is to eventually understand the effects of anthropogenic noise on the breeding success of the warblers. The anthropogenic component of the soundscape includes noise from road traffic, jet aircraft, helicopters, and urban development and utilization. During the 2016 and 2017 breeding seasons (March through May), acoustical recordings were made from sun up to sun down each day at four sites. The acoustical measurements were correlated with contemporaneous direct field observations that mapped the male territories and their degree of reproductive success. The study considered the interplay of the source levels of the warblers, the noise, and sound propagation loss in the habitat. The key result is the difference in the distribution of two song types sung by banded birds with different degrees of breeding success. The relationship between these distributions, the corresponding success rates, and the size of the acoustic active space as determined by soundscape characteristics, is discussed.