Maps and Data Tools
The Desert Tortoise Recovery Office collects and synthesizes current information relevant to desert tortoise status and recovery.
Range-wide Monitoring Data
The Desert Tortoise Recovery Office prepares line transect and associated visibility data to estimate desert tortoise densities each year across the range. Once they are prepared, these data can be requested for all years of the monitoring program since 2001.
Spatial Decision Support System
The Desert Tortoise Recovery Office, in collaboration with the University of Redlands is developing a spatial decision support system that estimates the impacts of threats to tortoise populations and identifies and prioritizes recovery actions that are most likely to ameliorate those threats. The decision support system models the inter-relationships among threats and tortoise population changes (i.e., which threats cause other threats, and how do these threats affect tortoise population numbers) and recovery action-population stress relationships (i.e., what are the most appropriate actions given a set of population stresses faced by the species?).
The decision support system utilizes primarily Geographic Information System data of the spatial extent of threats (i.e., where threats occur geographically) to calculate how changes in threats contribute to changes in tortoise population numbers.
Habitat Model for the Mojave Desert Tortoise
By applying information from the literature and knowledge or assumptions of environmental variables that could potentially explain variability in the quality of desert tortoise habitat, USGS researchers developed a quantitative habitat model for the Mojave desert tortoise using an extensive set of field-collected presence data. Sixteen environmental data layers were converted into a grid covering the study area and merged with desert tortoise presence data for input into a habitat-modeling algorithm. This model provides output of the statistical probability of habitat potential that can be used to map potential areas of Mojave desert tortoise habitat. The report and associated geospatial data are available here (http://pubs.usgs.gov/of/2009/1102/).