The Selvagens gecko (Tarentola boettgeri bischoffi Joger, 1984) is a medium sized gecko endemic to the Selvagens archipelago, Madeira, Portugal. The biology of this gecko is poorly known and in this study we present the first evidence regarding its habitat use. In 2010 (spring and autumn) and 2011 (spring), we collected data on the characteristics of the habitat surrounding 168 rocks used by these geckos as retreat sites, as well as on 75 randomly selected rocks. We also recorded body measurements of the individuals caught under each rock. In both seasons retreat site occupancy was found to be related to rock area, with geckos being found mainly under large rocks. Interestingly, we found that in spring heavier males, in better body condition, occupied the largest rocks and larger geckos occupied rocks closer to creek beds. Our results shed some light upon the behavioural ecology of this nocturnally active ectotherm, that spends the day under a retreat site: i) intraspecific competition may be an ecological factor prevalent in this species, since larger individuals occupy larger rocks, located in a presumably high quality micro-habitat; ii) the possibility of spring territoriality in males, that compete for good quality shelters
