Reproductive biology of the invasive bullfrog Lithobates catesbeianus in southern Brazil

We studied the reproductive biology of an invasive population of the bullfrog Lithobates catesbeianus by analyzing individuals captured in the central Rio Grande do Sul state, southern Brazil. Specimens were collected during 12 field trips held from May 2002 to June 2003. We analyzed gonad development stages in 216 individuals to evaluate the fecundity, reproductive effort, size—fecundity relationships, and seasonal distribution of individuals. Reproductive activity was potentially continuous, and was more intense during the spring and summer. The smallest mature male was 90.25 mm in snout—urostyle length (SUL); the SUL of the smallest mature female was 120.83 mm. The invasive potential of L. catesbeianus is probably associated with reproductive traits such as continuous gonad development, extended reproduction period, high fecundity, and early sexual maturity. The data presented here form a basis for future studies on the impacts and management of bullfrogs in invaded ecosystems.