Status of the Colorado Fringe-toed Lizard (Uma notata) within the Imperial Sand Dunes Recreation Are
U.S. Geological Survey
Western Ecological Research Center
Henderson, NV USA
Off-highway vehicle (OHV) recreation is increasing throughout the southwestern US, and can adversely affect habitat and abundance of many plants and animals. Within the Imperial Sand Dunes Recreational Area (ISDRA) in southeast California, USA, management plans have been implemented since 1974 and more intensely since 2000 to manage OHV activity in order to reduce disturbance impacts to sensitive wildlife such as the Colorado Fringe-toed Lizard (Uma notata) and sensitive plants. To understand the relationship among habitat, disturbance, and the ecological requirements for Uma lizards, we conducted a multi-year study (2014-2016) using stratified randomly placed transects throughout five ISDRA management areas. We surveyed environmental parameters including geographic location, air and surface temperatures, precipitation, wind speed, cloud cover, presence and number of OHV tracks, trash, and crushed vegetation as well as the abundance of key perennial vegetation species along each transect. We found that surface temperature (30-48 °C) and the abundance of the perennial plant Eriogonum deserticola best explained lizard detection and density. Lizard density increased in habitats providing the largest sand dunes and longer-term management (since 2000), restricting OHV activity. Although Wilderness areas within ISDRA were closed to OHV recreation in 1974, we found fewer lizards there than in other protected areas; much of the Wilderness area was represented by dunes stabilized by Larrea tridentata scrub vegetation or interspersed by ancient lakebed clay soils and may not represent optimal habitat for Uma lizards. Our findings support that management actions reducing OHV activity in high sand dune habitats over longer periods (>15 years) will likely increase the density of Colorado fridge-toed lizards and promote habitat features needed to support robust populations.