Microhabitats and population densities of California legless lizards, with comments on effectiveness of various techniques for estimating numbers of fossorial reptiles

摘要

We studied the cryptic fossorial legless lizard (Anniella pulchra) in a 1.57-ha area of sand dune on the coast of central California. This is the largest and most dense population of A. pulchra (N = 3,582; 0.228/m(2)) known to date. We documented distribution of animals through systematic removal and relocation of lizards at the site and with GIS analyses. Lizard density was high near shrubs and where soil moisture was greater but lower in disturbed soils and in iceplant. We also conducted time-constrained searches and coverboard surveys to analyze the efficacy of standard survey methods for legless lizards. Moderate-impact time-constrained searches were more effective in establishing presence of lizards when compared to low-impact time-constrained searches and coverboard surveys. Our data show that standard methods may not be effective in establishing presence or absence of this lizard at low densities. None of the survey methods was effective in predicting the density of lizards actually present.