Snake aggregation pheromones: source and chemosensory mediation in western ribbon snakes (Thamnophis proximus).

Aggregation with conspecifics is a robust phenomenon among snakes that is mediated by chemical cues, although the source of such cues is unknown. Adult western ribbon snakes (Thamnophis proximus) discriminated between skin lipid extracts from conspecifics and those from a sympatric heterospecific snake, the corn snake (Elaphe guttata). Additionally, ribbon snakes were attracted to conspecific skin lipid-marked shelters when paired with control-marked shelters, but no preference was exhibited when shelters marked with E. guttata skin lipids were paired with control-marked shelters. Furthermore, prevention of chemical access to the vomeronasal organs of T. proximus eliminated the ability to respond to conspecific skin lipids. These results indicate that epidermal lipids are the source of chemical cues mediating attraction to shelters marked by conspecifics and that such signals are detected by the vomeronasal system.