Enhancing line-transect distance sampling to increase detectability of gopher tortoises (gopherus polyphemus) in population surveys

Gopher tortoise (Gopherus polyphemus) populations are declining range-wide and accurate abundance and demographic estimates are needed for proper management of the species. I developed a series of Bayesian hierarchical models to estimate the density and size demography of gopher tortoise populations while accounting for size bias against smaller individuals. In conjunction with the estimation models, I designed a survey to incorporate randomly located double-sampling blocks and systematic vegetation measurements into the standard distance sampling methodology to better account for sources of variability known to affect detection of all tortoises. My results suggest that my hierarchical models and double-sampling survey method may increase the accuracy and precision of both density point estimates and the underlying burrow size distribution estimates of gopher tortoise populations.