Abstract

Although our understanding of the behavior of frogs during breeding events is substantial, a gap exists in our knowledge of the behavior and physiology of these animals during nonreproductive periods. We used field sampling of Gray Treefrogs, Hyla versicolor, to measure body condition and steroid hormone levels of breeding and dispersed nonbreeding frogs throughout the active seasons for this species. Gray Treefrog females in the act of breeding showed the greatest elevation of all measured steroids, and females that dispersed away from breeding ponds had greater plasma estradiol and testosterone during the breeding season relative to the nonbreeding season. There was no relationship between progesterone levels and season for dispersed females. Dispersed females were not more likely to show elevated levels of gonadal steroids if they were found closer to the breeding pond and did not move to refugia closer to the breeding ponds as breeding time approached, supporting the hypothesis that migration to breeding ponds is a rapid event in this species. Body condition of females captured during the breeding season did not significantly differ from those captured after the season, and body condition was not correlated with reproductive steroid levels. Our findings suggest that for female Gray Treefrogs, breeding migrations are rapid, and reproductive activity is not strongly condition-dependent in this species.