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24 August 2018 Estimating Occupancy and Detectability of Toad Headed Agamas at the Periphery of Their Range in Mongolia
Oyunchuluun Yadamsuren, James D. Murdoch, Suvdtsetseg Chuluunbat, Erdenetushig Purevee, Munkhbaatar Munkhbayar, Ariunbold Jargalsaikhan, Zoljargal Purevjargal, Munkhbayar Khorloo, Terbish Khayankhyarvaa
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Abstract

Populations at the periphery of a distribution often are genetically and ecologically distinct but tend to be less represented in conservation planning. Peripheral populations may exhibit different behaviors and persist longer than core populations as landscapes change, especially because of human-induced habitat loss and climate change. We examined how landscape factors influence occupancy patterns of Toad Headed Agamas (Phrynocephalus versicolor) along the northern periphery of their range in Asia, a region experiencing increasing development and warming conditions. We collected detection/nondetection data during surveys of 180 sites in Mongolia in 2016. We then developed a set of 70 candidate models that included the single, additive, and interacting effects of nine covariates on occupancy and detection probability and used model selection techniques to determine the best model in the set. We detected agamas at 89 sites (49.4%) and during 141 (39.2%) of 360 surveys. Only one model had strong empirical support, one which included the additive effects of forb cover, grass cover, and ruggedness on occupancy probability and wind speed on detection probability. All four covariates had negative effects, suggesting that ideal conditions for occupancy were areas with little vegetation and topographically flat or gently rolling and that detection was higher in low wind. Average predicted occupancy across all sites was 55%. Our results indicated agamas were more sensitive to vegetation cover in this area than in other parts of their range. Agamas may benefit from future climate conditions that reduce vegetation but face negative impacts from increases in landscape ruggedness because of development activities.

Copyright 2018 Society for the Study of Amphibians and Reptiles
Oyunchuluun Yadamsuren, James D. Murdoch, Suvdtsetseg Chuluunbat, Erdenetushig Purevee, Munkhbaatar Munkhbayar, Ariunbold Jargalsaikhan, Zoljargal Purevjargal, Munkhbayar Khorloo, and Terbish Khayankhyarvaa "Estimating Occupancy and Detectability of Toad Headed Agamas at the Periphery of Their Range in Mongolia," Journal of Herpetology 52(3), 361-368, (24 August 2018). https://doi.org/10.1670/17-157
Accepted: 14 June 2018; Published: 24 August 2018
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