Modeling Louisiana pine snake (Pituophis ruthveni) habitat use in relation to soils
Ongoing surveys suggest that Pituophis ruthveni (Louisiana Pine Snake) has declined range-wide and that known extant populations have continued to decline. Seven known populations remain and occupy small, isolated blocks of habitat. Population sizes are unknown, but all of them are believed to be critically small. Management for the species’ recovery requires an understanding of its habitat requirements and how resources used by these snakes are distributed in space. Research suggests that the species’ primary prey, Geomys breviceps (Baird’s Pocket Gopher), prefers sandy, well-drained soils. Thus soil attributes may be used to identify potential Louisiana Pine Snake habitat. Using Natural Resources Conservation Service Soil Survey Geographic Database (SSURGO) soil characteristics and available historical and recent telemetered snake locations, we developed resource selection functions describing Louisiana Pine Snake potential habitat at two spatial scales. SSURGO variable hydgrp, a soil characteristic developed for modeling precipitation runoff, incorporating soil permeability and depth to ground water, best predicted species occurrence and was used to map potential habitat selection and identify areas of high conservation value. Our model demonstrates that the distribution of Louisiana Pine Snakes on the landscape is strongly influenced by edaphic factors, which are unlikely to be changed at a landscape scale by human activities. Ample area of suitable soils remains available to support the species throughout its historical range; however, we suspect that a miniscule fraction of the potential habitat we identified has suitable vegetation communities on-site to support Louisiana Pine Snakes.