Demographics of an Ornate Box Turtle Population Experiencing Minimal Human-Induced Disturbances

Abstract

Human‐induced disturbances may threaten the viability of many turtle populations, including populations of North American box turtles. Evaluation of the potential impacts of these disturbances can be aided by long‐term studies of populations subject to minimal human activity. In such a population of ornate box turtles (Terrapene ornata ornata) in western Nebraska, we examined survival rates and population growth rates from 1981–2000 based on mark–recapture data. The average annual apparent survival rate of adult males was 0.883 (se = 0.021) and of adult females was 0.932 (se = 0.014). Minimum winter temperature was the best of five climate variables as a predictor of adult survival. Survival rates were highest in years with low minimum winter temperatures, suggesting that global warming may result in declining survival. We estimated an average adult population growth rate (λ^) of 1.006 (se = 0.065), with an estimated temporal process variance (σ^2) of 0.029 (95% ci = 0.005–0.176). Stochastic simulations suggest that this mean and temporal process variance would result in a 58% probability of a population decrease over a 20‐year period. This research provides evidence that, unless unknown density‐dependent mechanisms are operating in the adult age class, significant human disturbances, such as commercial harvest or turtle mortality on roads, represent a potential risk to box turtle populations.

Social, biological, and environmental drivers of the hunting and trade of the endangered yellow-footed tortoise in the Amazon

“…In this case, hunting is the main variable that influences tortoise prices. Converse et al (2005) suggested that tortoises have low population growth rates, which hinders the recruitment of individuals in the case of mortality on a large scale. In contrast, Hailey (2000) suggested that the spur-thighed tortoise (Testudo graeca) has high productivity under management, indicating potential for its sustainable use.…”

Demographic and genetic status of an isolated population of bog turtles (Glyptemys muhlenbergii): implications for managing small populations of long-lived animals

“…Although bog turtles are typically sedentary, they can undertake large-scale overland movements between habitat patches (Morrow et al 2001a). Habitat fragmentation therefore may impact bog turtle populations by preventing dispersal, disrupting metapopulation dynamics, and increasing the threat of local population decline through stochastic factors (Converse et al 2005;Lande 1993).…”

Evidence that a Highway Reduces Apparent Survival Rates of Squirrel Gliders

“…Population studies are an alternative method of quantifying impacts such as road mortality on small species, with differences in demographic rates across space and through time indicating ecological effects (Ruggiero et al 1994, Marschall and Crowder 1996, Gill et al 2001, Converse et al 2005, Yasué and Dearden 2006. These demographic rates may also inform research on the dynamics of population size (McCallum 2000), and assessments of population viability (Akçakaya and Sjögren-Gulve 2000), in turn providing information to assist management decisions (Drechsler andBurgman 2004, van der Grift andPouwels 2006).…”