U.S. Department of Agriculture: Animal and Plant Health Inspection Service


Date of this Version

May 2003


Published by Zoo Biology 22:227–238 (2003).


Two different temperature regimes for eliciting reproduction in male and females of the Guam form of the brown treesnake were investigated. Males and females maintained at 24°C followed by a 60-day cool period at 19°C exhibited substantial reproductive activity, and the females that produced clutches did so during a brief period after return to 24°C. In contrast, individuals maintained at 28°C followed by an identical 19°C cooling period exhibited relatively little reproductive activity, and although some females became vitellogenic, none produced eggs. Reproductive activity was virtually absent in all individuals in both groups 7 months after the end of the cool period. Thus, a period of cool temperatures elicits reproductive activity in both sexes and the effect is transitory. Temperatures experienced during the cool period were much lower than the snakes would experience on Guam, and temperatures there are also relatively invariant. Thus, it is possible that only minor fluctuations in temperature are sufficient to elicit reproduction in the Guam population. Because the Guam form does well under, and responds reproductively to, unusually cold temperatures for a lowland tropical reptile, concern that it may have the capacity to invade extralimital temperate areas is warranted. Zoo Biol 22:227–238, 2003. Published 2003 by Wiley-Liss, Inc.