Biology of the Ringneck Snake, Diadophis punctatus, in Florida

Abstract

Two geographic color varieties of the ringnack snake, Diadophis punctatus punctatus (Linnaeus), occur in Florida. Snakes in the Peninsula are characterized by reddish subcaudal surfaces and by the curious trait of tail-coiling when disturbed; the snakes occupying extreme northern Florida have yellow subcaudal surfaces and do not tail-coil. In the intergrade zone the subcaudals vary from yellow through red and some yellow-tailed individuals will tail-coil. The color red and the associated tail-coil display are considered relict characters in Gulf Coastal ringneck snakes. Ways are enumerated whereby tail-coiling may serve an aposematic function. The almost universal occurrence of the color red in snakes that have tail-flash displays suggests the behavior may have been developed against birds; most other potential predators lack red vision. Diadophis punctatus has been found in practically all the major terrestrial habitats in Florida, although most commonly in low, wet, pine flatwoods. Main factors determining the species' ecological distribution and population density seem to be food and degree of moisture in the microhabitat. Significant size differences in snakes of two different populations may be related to availability of food. Microhabitat associates in two different habitats are considered, and known and supposed coactions discussed. Other snakes are probably the most important predators and competitors for food and space. The sex ratio in adults, at least, is 1:1. The gonads are bilaterally asymmetrical in position and usually in size. The testes are smallest in winter and spring. Spermatogenesis is initiated in the spring and cellular proliferation is greatest in summer. Spermatozoa released from the testis in late summer and fall are stored in the ductus deferens throughout most of the year. The largest ovarian eggs increased from approximately 3 mm in April to a near maximum of 24 mm in July when they were in the oviducts. Eggs are probably laid from late May or June into August; females probably lay each year; the time of mating is not known. Both sexes are thought to be sexually mature by their second spring. The male secondary sex characters-anal ridges and greatly enlarged kidney tubules-become apparent about when the spermatozoa are formed. A series of prehatching stages is briefly described. Males carry the hemipenes in tbe functional (everted) position until at least 28 days before hatching. Ventral markings are not apparent until after the dorsum becomes lightly pigmented. The unpigmented dorsal scale pits are the last structures to become discernible.