Modeling habitat connectivity to inform reintroductions: a case study with the Chiricahua leopard frog

Abstract/Summary

Managing a species with intensive tools like reintroduction may focus on single sites or entire landscapes. For vagile species, long-term persistence will require colonization and establishment in neighboring habitats. Thus, both suitable colonization sites and suitable dispersal corridors between sites are required. Assessment of landscapes for both requirements can contribute to ranking and selection of reintroduction areas, thereby improving management success. Following eradication of invasive American bullfrogs (Lithobates catesbeianus) from most of Buenos Aires National Wildlife Refuge (BANWR; Arizona, USA), larval Chiricahua leopard frogs (L. chiricahuensis) from a private pond were reintroduced into three stock ponds. Populations became established at all three reintroduction sites, followed by colonization of neighboring ponds in subsequent years. Our aim was to better understand colonization patterns by the federally-threatened L. chiricahuensis, which could help inform other reintroduction efforts in the region. We assessed the influence of five landscape features on colonization. Using surveys from 2007 and information about the landscape, we developed a habitat connectivity model based on electrical circuit theory that identified potential dispersal corridors, after explicitly accounting for imperfect detection of frogs. Landscape features provided little insight into why some sites were colonized and others were not, results that are likely due to the uniformity of the landscape at BANWR. While corridor modeling may be effective in more complex landscapes, an approach more focused on local habitat is required at BANWR. We also illustrate that existing data, even when limited in spatial or temporal resolution, can provide information useful in formulating management actions.