Modeling Louisiana pinesnake habitat to guide the search for population relicts
Pituophis ruthveni (Louisiana Pinesnake) is one of the rarest snakes in the United States. Efforts to refine existing habitat models that help locate relictual populations and identify potential reintroduction sites are needed. To validate these models, more efficient methods of detection for this rare species must also be developed. Here we expand recent habitat suitability models based on edaphic factors to include mature Pinus (pine) stands that have not been cut for at least 30 years and likely have vegetation structure with the potential to support the species. Our model identified a total of 1652 patches comprising 180,050 ha of potentially suitable habitat, but only 16 (1%) of these patches were more than 1000 ha and considered worthy of conservation attention as potential reintroduction sites. We also visited potentially suitable habitat, as determined by our model, and used camera traps to survey for relictual populations at 7 areas in Texas. We observed 518 snakes of 18 species in 8,388,078 images taken from April to October 2016, but no Louisiana Pinesnakes were detected. The patchiness of the habitat model and failure to detect Louisiana Pinesnakes corroborate independent conclusions that most populations of the species are small, isolated, probably in decline, and possibly extirpated. In the context of this extreme rarity, we believe this study will help manage limited conservation resources by narrowing the search areas for relictual populations, providing a more cost-effective method of surveying those areas, and identifying the best sites for future reintroduction efforts.