Landscape and the Occupancy of Pampean Grassland Birds: Modelling Site Occupancy Through Acoustic Detection

Native grasslands worldwide are under threat from replacement by cropland and other land-use practices, resulting in severe population declines of grassland birds in recent decades, due to their sensitivity to changes in land use. We fitted occupancy models to data collected by passive acoustic monitoring of bird species at sites in Brazilian pampas grasslands (dry grass, wet grass and regenerating grass) to test the hypothesis that the probability of local site occupancy of grassland-specialised birds, Ammodramus humeralis Cabanis & Heine, 1850 (grassland sparrow), Emberizoides herbicola Cabanis, 1847 (wedge-tailed grass-finch) and Leistes superciliaris Vigors, 1825 (white-browed meadowlark), decreases with native land-use change; but not for the habitat-generalist species Zonotrichia capensis Cabanis & Heine, 1850 (rufous-collared sparrow). Land cover and land use were quantified within 500 m buffers around 69 grassland study sites and were used as covariates in site-occupancy models. The probability of occupancy of L. superciliaris at a site was positively influenced by native grassland cover and agriculture in the surrounding landscape, while A. humeralis was negatively influenced by forest cover. For E. herbicola and the generalist Z. capensis, the occupancy probability was not influenced by the measured landscape variables. These four grassland species present varied responses to land cover and land use in grasslands, highlighting the need for a better understanding of predictors at a habitat scale to effectively inform management and conservation strategies for grassland areas. This study underscores the importance of conserving native grasslands, as species distribution tends to remain stable in areas with well-preserved grassland cover, a finding that can inform conservation efforts in other grassland regions worldwide.