Seasonal sexual cycle of Nerodia taxispilota (Serpentes: Colubridae) at the northeastern edge of its range
Date of Award
Master of Science
The seasonality of the sexual cycle of Nerodia taxispilota at the northeastern edge of its range was elucidated from specimens collected over a two-year period (1978-1979) from the Appomattox River near Hopewell, Virginia. The investigation centered on morphological changes in the testis of males and vitellogenesis and embryo development in females. Related reproductive parameters also studied were body size differences, seasonal sex ratios, comparative tail lengths, and tail mutilation.
Male and female cycles closely resembled those of other temperate zone colubrids. Spermatogenesis began in May and testis size peaked in late August. Testis length showed a time lag when compared with weight and volume. Sperm produced during summer were stored in the vas deferens through winter and used the following spring. The female cycle is apparently annual. Vitellogenesis occurred only in spring, ovulation was in mid-June, and parturition was probably in late August or early September. The number of young increased with increasing female body size with mean clutch size of full-term embryos 28.0.
Females were generally larger than males. Sex ratio was about 1:1 in spring and summer, however males predornina ted in fall. Males had comparatively longer tails than females. The amount of tail breakage was about equal for both sexes.
White, David Roland, "Seasonal sexual cycle of Nerodia taxispilota (Serpentes: Colubridae) at the northeastern edge of its range" (1980). Master's Theses. 1098.