Emergence and dispersal of snakes after syntopic hibernation

Abstract

A communal hibernaculum situated in Southwestern Bulgaria and its adjacent area (4 km in diameter) was studied. Seven snake species used this hibernating den, Malpolon insignitus, Dolichophis caspius, Platyceps najadum, Elaphe quatuorlineata, Telescopus fallax, Vipera ammodytes and Xerotyphlops vermicularis. The emergence of the snakes was related to the rise of daily temperatures. Malpolon insignitus emerged from hibernation earlier in the spring than the other species, and most individuals were the first to leave the hibernaculum. There was a temporal segregation among the basking area in early spring, between the latter species and D. caspius, which were the two most abundant species. These two species also used the same area of the hibernaculum, in contrast to P. najadum and E. quatuorlineata, which used a different area. After spring dispersal, M. insignitus and D. caspius used the same microhabitats during the rest of the active period. The earlier emergence of M. insignitus (and earlier departure from the site) probably reduces the competition for basking sites. The early departure of the species may give advantage in the competition for optimal microhabitats with D. caspius.