Microhabitat use of two sympatric geckos, Turner's thick-toed gecko (Chondrodactylus turneri) and the Common Namib Day Gecko (Rhoptropus afer)

Abstract

Differences in microhabitat use can lead to habitat segregation that reduces competition. We studied the natural history, activity, and microhabitat use of Turner's Thick-toed Gecko (Chondrodactylus turneri) and the Common Namib Day Gecko (Rhoptropus afer) in the Namib Desert. Both species were associated with the same rocky habitat but exhibited differences in activity (i.e., times of day when visible out of crevices) and microhabitat use (i.e., characteristics of rocks occupied). Two 48-hr surveys revealed peaks of activity starting at 2000 h for C. turneri and 1000 h for R. afer. To evaluate microhabitat use, we measured rock characteristics, quantifying rock dimensions and counting the number of small loose rocks. In addition, we counted and categorized crevices, and determined the temperature of some crevices over a 3-day period. Rock height was positively correlated to C. turneri presence, whereas rock width and length were positively associated with R. afer presence. Availability of loose rocks and medium-sized crevices were also strong predictors for R. afer occupancy. Crevices occupied by R. afer were warmer than those occupied by C. turneri. Stability in this desert lizard community is based on occupancy of different areas of the rocks (microhabitat variation) at different peak times (activity variation).