Landscape and management factors influence the occupancy dynamics of sympatric salamanders in an urban preserve system

Abstract

Conserving amphibian populations living in urban areas is challenging due to a lack of information about urban amphibian natural history, ecology, and responses to habitat management. To address these knowledge gaps, we used 10 years of monitoring data to investigate patterns of occupancy, detectability, and population turnover for sympatric Ambystoma laterale (Blue-spotted Salamanders) and A. tigrinum (Eastern Tiger Salamanders; hereafter Tiger Salamanders) inhabiting 26 suburban preserves in the third largest metropolitan area in the United States, Chicago. From 2009 to 2018 we conducted 2181 artificial cover object surveys at 158 randomly distributed monitoring points and detected Blue-spotted Salamanders 375 times and Tiger Salamanders 85 times. We constructed dynamic occupancy models and used an information theoretic approach to rank a priori candidate models containing landscape, survey, and management covariates. Blue-spotted Salamander occupancy was more than twice as high as Tiger Salamander occupancy. Detection probability for both species was substantially <1 and was influenced by both survey and landscape covariates. Prescribed fire was an important predictor of colonization for Blue-spotted Salamanders and both species exhibited higher rates of colonization at sites near breeding wetlands. Overall rates of turnover were low for both species. Our results reveal that salamander populations can persist in highly fragmented urban preserve systems. We recommend that urban land managers maintain a mosaic of forests and wetlands and consider the impacts of habitat management on non-target species (such as salamanders).