Using movement to inform conservation corridor design for Mojave desert tortoise
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RESEARCH
Open Access
Using movement to inform conservation corridor design for Mojave desert tortoise Steven J. Hromada1,2* , Todd C. Esque3, Amy G. Vandergast4, Kirsten E. Dutcher2, Corey I. Mitchell2, Miranda E. Gray5, Tony Chang5, Brett G. Dickson5,6 and Kenneth E. Nussear2
Abstract Background: Preserving corridors for movement and gene flow among populations can assist in the recovery of threatened and endangered species. As human activity continues to fragment habitats, characterizing natural corridors is important in establishing and maintaining connectivity corridors within the anthropogenic development matrix. The Mojave desert tortoise (Gopherus agassizii) is a threatened species occupying a variety of habitats in the Mojave and Colorado Deserts. Desert tortoises have been referred to as corridor-dwellers, and understanding how they move within suitable habitat can be crucial to defining corridors that will sustain sufficient gene flow to maintain connections among populations amidst the increases in human development. Methods: To elucidate how tortoises traverse available habitat and interact with potentially inhospitable terrain and human infrastructure, we used GPS dataloggers to document fine-scale movement of individuals and estimate home ranges at ten study sites along the California/Nevada border. Our sites encompass a variety of habitats, including mountain passes that serve as important natural corridors connecting neighboring valleys, and are impacted by a variety of linear anthropogenic features. We used path selection functions to quantify tortoise movements and develop resistance surfaces based on landscape characteristics including natural features, anthropogenic alterations, and estimated home ranges with autocorrelated kernel density methods. Using the best supported path selection models and estimated home ranges, we determined characteristics of known natural corridors and compared them to mitigation corridors (remnant habitat patches) that have been integrated into land management decisions in the Ivanpah Valley. Results: Tortoises avoided areas of high slope and low perennial vegetation cover, avoided moving near lowdensity roads, and traveled along linear barriers (fences and flood control berms). (Continued on next page)
* Correspondence: [email protected] 1 Program in Ecology, Evolution and Conservation Biology, University of Nevada, 1664 N. Virginia St, Reno, NV 89557, USA 2 Department of Geography, University of Nevada, 1664 N. Virginia St, Reno, NV 89557, USA Full list of author information is available at the end of the article © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included
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