Parental Investment in the Chicken Turtle (Deirochelys Reticularia)

Abstract

Eggs of the chicken turtle (Deirochelys reticularia) were collected in South Carolina from clutches laid in the spring and fall. Clutch size averaged 8.0 eggs (2 SE = 1.6; n = 15) and was weakly correlated with body size of the female. Wet mass of the clutch averaged 72.4 g (2 SE = 11.6, n = 15). There were no significant differences in clutch size or wet mass between spring and fall nesting seasons. Individual eggs laid in the fall (° = 10.7 g) were significantly larger than those laid in the spring (° = 8.5 g). Fifteen eggs laid in the spring and incubated at 29° ± 2°C averaged 152 d to hatching. Hatchling plastron length averaged 24.3 mm, and body wet mass was 6.7 g. Hatchlings (dry mass) contained 27.4% lipid, and the lipids remaining in the neonate at hatching represented 61% of the lipids originally present in the egg. The wet mass of hatchling is highly correlated with wet mass of the egg. In contrast to clutch size, egg size had a strong positive relationship to body size. A morphological constraint, the width of the pelvic canal, is proposed as having an influence on this relationship. The negative relationship between an optimized egg size and clutch size was not evident, so current optimality models do not appear to be applicable to Deirochelys.

Morphological constraint on egg size: a challenge to optimal egg size theory?

“…Some x-rayed females were given injections of oxytocin (22) to induce them to lay eggs. Egg width can be determined directly from x-ray photographs and is strongly correlated With egg wet mass, dry mass, lipids or total energy content, and size of hatchlings (19). Egg length to egg width ratios of freshly laid eggs were similar for all three species: C. picta = 1.75; D. reticularia = 1.67; and P. scripta = 1.64.…”

“…Within the assumptions of optimal egg size theory, this suggests that different optima exist within a population at different times. However, the degree of difference between clutches in lizards is substantially smaller than the range in variation in egg size found in turtle populations of some species (19,20). The option for adjustments in clutch size of course does not apply to lizards with fixed clutch size such as geckos, some skinks, most microteids, and iguanid lizards of the genus Anolis.…”

Deirochelys reticularia (Latreille 1801) – Chicken Turtle

“…The 8.5 g for those laid in the spring (Congdon et al 1983;Congdon and Gibbons 1985). Mean egg length for females from Florida was 36.5 mm, and mean egg mass was 10.7 g (Jackson 1988).…”

DOE Research Set-Aside Areas of the Savannah River Site

“…Some of these studies have used a drift fence method to determine the activity and movement patterns of particular species of reptiles and amphibians and a number of studies have been conducted on the reproductive biology of turtles (Gibbons and Nelson, 1978;Congdon et al, 1983;Condon and Gibbons, 1985). Research on the reproductive biology of salamanders has been conducted at Risher Pond by Sever et al (1996) and studies investigating the effects of fish #competition and predation on salamanders has been conducted by Semlitsch (1987.…”