Somatic Growth and Maturity for Four Species of River Cooter Including Pseudemys concinna suwanniensis, P. nelsoni, P. peninsularis, and P. texana

Pseudemys is a genus of commonly occurring freshwater turtles with limited growth information across their long lifespans. We used 11,361 mark-recapture events to estimate the somatic growth rates of P. nelsoni, P. peninsularis, P. concinna suwanniensis, and P. texana from freshwater springs and developed a Bayesian growth model to estimate the species-specific, site-specific, and individual effects on growth. We corroborated evidence for fast juvenile growth and slower adult growth in Pseudemys but found uncommonly fast growth rates, with turtles doubling or tripling in size in the first year. P. texana males had the smallest average maximum size (L∞, 243 mm), while P. c. suwanniensis females had the largest (423 mm). Environmental conditions at springs had significant effects on k, the growth coefficient, but not L∞. We derived, using a ratio of length at maturity to L∞ (71.7% and 87%, males and females), that females matured 1.15-1.57 times older than males except for P. c. suwanniensis, which matured three times older. Given the local abundance declines in many Pseudemys from anthropogenic impacts, this study provides important baseline life history information for Pseudemys species for use in ongoing conservation efforts and presents a novel hierarchical modeling approach using a long-term mark-recapture dataset.

Ecological Aspects of a Wood Turtle,

As part of a conservation research initiative, a population of Wood Turtles (Glyptemys insculpta) at the northern limit of its range was studied to ascertain characteristics of its demographics, morphometrics, density, mortality, feeding, and mating activities. Turtles were captured and marked during the activity period in 1996 and 1997. In addition, 20 individuals were radio-tracked weekly. A total of 188 turtles was captured and the size of the population in the study area was estimated at 238 turtles. The estimated population density based on this calculation is 0.44 turtles/ha. This is less than other studies indicating that population densities are greater in southern populations. Turtles from this population were large (carapace length of males=214.5 ± 4.21 mm, females=201.1 ± 10.88 mm) which supports the hypothesis that turtle size is negatively correlated with number of frost free days. The sex ratio was not significantly different from 1:1. Juvenile turtles accounted for 31.4% of the population. Observations of feeding habits support the claim that Wood Turtles are opportunistic omnivores. Of the 35 mating or courtship events observed, 77 % occurred in the fall and half of them between 11:00 and 13:00. Although limb and tail injuries and parasites were observed on many turtles, no dead turtles were observed. This last result, combined with the high rate of recruitment and even sex ratio suggests that this population is stable, making it an ideal population with which to make comparisons with other studies in areas where the species could be in decline.