Hormonal control of male courtship behavior and female attractivity in the garter snake (Thamnophis sirtalis sirtalis)

Mating behavior in both intact and gonadectomized garter snakes (Thamnophis sirtalis sirtalis) was measured following hormone administration. Male courtship was androgen-dependent; subcutaneous implants of crystalline testosterone propionate (TP) pellets induced mating behavior within 2 days in both intact, reproductively inactive males and castrated males. Female attractivity, as measured by male courtship of the female, was stimulated by exogenous estrogen; 20 μg/day of estradiol benzoate (EB) was the minimum effective dose for stimulating female attractivity in both intact, reproductively inactive females and ovariectomized females. TP-implanted males selectively courted EB-primed females in both sequential and simultaneous (choice) mating tests. It is probable that males use estrogen-dependent olfactory cues produced by the females to discriminate between hormone- and vehicle-injected females.