If You Burn It, They Will Come: Collared Lizard Colonization of Ozark Mountains Under Prescribed Burns

In 1982 a conservation project was initiated to restore glade communities in the Missouri Ozarks with a special emphasis on collared lizards ( Crotophytus collaris ), a state threatened species at the time. Starting in 1984, collared lizards were translocated onto restored glade habitats on Stegall Mountain in the Ozarks. The populations persisted but did not colonize other glades on Stegall until 1994, when prescribed fires included not only the glades, but also the surrounding woodland. Starting in 1999, landscape-level burns connected Stegall to three nearby mountains. The goal of this study was to test the hypothesis that expanding prescribed burns to the forested woodlands between Stegall Mountain and nearby mountains would create dispersal corridors for the colonization of glades on new mountains. Indeed, all three mountains were colonized and direct dispersal of marked lizards from Stegall was observed following the prescribed fires. Inter-mountain colonization dynamics and patterns varied: one was absorbed into the Stegall meta-population, another experienced a founder event followed by rapid colonization, and the third underwent repeated failed colonization attempts before successful establishment years later. These diverse patterns were consistent with differences in landscape resistance in the inter-mountain corridors rather than in geographical distance. Intra-mountain colonization patterns indicated that lizards assessed glade quality based on multiple factors. High landscape resistance resulted in a young age structure in the initial colonizing population. This young age structure interacted with the territorial behavior of collared lizards, age of reproduction, and probability of dispersal. This strong interaction between landscape resistance in the dispersal corridor and social behavior in the colonizing population is a novel factor in predicting colonization dynamics. Moreover, these results highlight the importance of social behavior on dispersal decisions versus habitat quality alone.