Assessing the feasibility for reintroducing desert bighorn sheep to Guadalupe Mountains National Park: Habitat, migration corridors and challenges

• GIS techniques identified suitable habitat for bighorn sheep reintroduction.
• High quality suitable habitat was found to encompass 79.95 km2 of terrain.
• Migration corridors to and from neighboring, populated terrains were identified.
• Consideration should be given to water development, competitors and predators.
• Natural colonization should not be discounted.

Desert bighorn sheep were once part of the Guadalupe Mountains ecosystem but were extirpated in the 1930s due to disease transmittance from domestic sheep and goats, habitat loss, and unregulated hunting. The Guadalupe Mountains (Texas) are now managed by the National Parks Service which wishes to restore native species to their historical range. A habitat suitability study is an important step in restoring desert bighorn sheep to the mountains since restoration efforts are labor intensive and costly. This study uses Geographic Information System (GIS) modeling to identify suitable areas within the park for bighorn sheep and evaluate possible migration corridors between the park and a nearby mountain range (Sierra Diablo) that currently supports more than 400 bighorn sheep. Landscape analysis was conducted to compare the spatial attributes of the habitat areas in the Guadalupe Mountains to those in the Sierra Diablo Mountain Range and assess habitat quality. Our results found 79.95 km2 of suitable habitat for desert bighorn sheep in Guadalupe Mountains National Park which exceeds the established size to support a minimum viable population size of bighorn sheep (100–125 individuals). Landscape analysis indicated a larger area of optimal habitat at the park with larger mean patch size, lower edge density, and shorter mean nearest neighbor distance than in the Sierra Diablo mountain range. The Sierra Diablo was found to have a larger area of suitable habitat which may indicate that the park may be able to support a smaller population if water development mirrors that of the Sierra Diablo. Several migration corridors were identified between the park and areas with a viable population of bighorn sheep and this connectivity is important for migration and gene flow. Considerations should be given to water development, non-native, competitor species (Barbary sheep) and predators (mountain lions).