AbstractsBiology & Animal Science

Pheromonal mediation of reproductive behavior in the brown tree snake

by Michael John Greene

Institution: Oregon State University
Department: Zoology
Degree: PhD
Year: 1998
Keywords: Brown tree snake
Record ID: 1692232
Full text PDF: http://hdl.handle.net/1957/33273


In animals, reproductive behaviors serve to attract individuals together during the breeding season and to coordinate the behavioral and physiological states of individuals so that mating can successfully occur. In snakes, the various reproductive behaviors including courtship, mating, courtship inhibition, male combat and trailing are mediated primarily by pheromones. Pheromones are naturally produced chemical signals that influence the physiology or behavior of a conspecific when released by one individual into the environment. The research included in this study was designed to characterize the role pheromones play in the mediation of reproductive behaviors of the brown tree snake (Boiga irregularis) a rear-fanged, arboreal colubrid native to Australia, Papua-New Guinea and the Solomon Islands. Much attention has been paid to this species as it is an introduced pest species on the Pacific island of Guam where it has caused considerable economic and ecological damage. In order to create behavioral bioassays designed to experimentally determine the role pheromones play in the mediation of brown tree snake reproductive behavior, the complete repertoire of courtship, mating and male combat behaviors were described. Male brown tree snakes display combat and courtship behaviors similar to other colubrid species while female brown tree snakes take a very active role in courtship, displaying behaviors that both release and inhibit male courtship. These data represent the first description of any reproductive behaviors in this species and one of only a few studies examining the reproductive behaviors of a tropical species. A behavioral bioassay measuring the release of male courtship behavior was utilized to isolate and characterize the female sex pheromone of this species as a suite of non-polar, non-volatile skin lipid molecules. Using another bioassay, the pheromonal inhibition of male courtship behavior by a volatile pheromone originating from female cloacal secretions was characterized. Lastly, pheromone mediated mate attraction was examined by determining the abilities of male brown tree snakes to follow conspecific pheromone trails during the breeding season. Male brown tree snakes possess the ability to follow both male and female pheromone trails but did not, however, discriminate between male and female pheromones trails when given a choice.