The reproductive biology of the Montpellier snake (Malpolon monspessulanus) under natural conditions is poorly known. It is commonly accepted that, as in other colubrids, it lays its eggs under dry leaves (Naulleau, 1984) or in crevices in the ground (Hailey, 1982). Burger & Zappalorti (1986), while noting that the reasons for nest site selection have not been studied in snakes, suggest predator avoidance and protection of eggs from inclement weather. Both factors may be extremely important for nest-site selection in our study area, the Doñana National Park (37°7′, 36°48′ N; 6°12′, 6°30′ W) which is extremely dry, with hot summers and mild winters. Montpellier snakes lay their eggs in mid-July, well into the summer (mean rainfall = 4°7 mm; average temperature = 22°28 °C, for June, July and August period). Additionally, densities of potential predators are also very high (Valverde, 1967). Consequently, selection of protected nest sites is likely to be extremely advantageous for this snake since both predation and desiccation of eggs will be reduced. As the sandy ground lacks natural crevices and holes, the use of dens of animals such as bee-eater galleries (Alvarez, 1974) and rabbit warrens may be favoured.