Animal Transect Data

Jackrabbits and desert cottontail rabbits are the most abundant non-domestic herbivores in the Chihuahuan Desert. We hypothesize that lagamorph populations were extremely low in desert grasslands prior to desertification because rabbits depend upon shrubs for water (bark and small stems), during the winter dry season. Data on population densities of rabbits in various habitats over a series of years is needed to test this hypothesis. We further hypothesize that rabbit populations will crash when winters and early summers are especially dry. Birds can be sensitive indicators of environmental change and also respond to habitat structure. We census birds on regular basis to examine the variability in patterns of abundance among habitats and among years. We predict that grassland and mesquite dune habitats will support fewer birds than the more heterogeneous shrubland habitats. Location and methods. Transects 1 km in length have been established in one area in each of 5 habitats. Three-meter lengths of rebar were driven into the soil at 50 m intervals. Each length has a section of whit PVC pipe attached to the top to facilitate line of sight orientation by an observer. An observer walks each transect once every two weeks