Demographics of a Painted Turtle (Chrysemys Picta) Population Responding to Drought in the Nebraska Sandhills

A large portion of herpetofauna species are declining as a result of anthropogenic influences such as habitat destruction and climate change, and turtles are no exception. Studying demographics of turtle populations in a wide variety of settings could help establish a baseline for future species management because demographics such as survival and movement are essential to understanding the ecology of a species. We conducted a long-term mark-recapture study on painted turtles (Chrysemys picta) in a permanent pond in the Nebraska Sandhills to exam population size, survival, and movement of an aquatic turtle as drought conditions changed in a water-limited system. The population size ranged from 92 (CI: 90 – 94) to 180 (CI: 175 – 186). A robust design analysis indicated that there is strong evidence that drought has a significant influence on survival in both male and female turtles. The top model estimated that survival was reduced by 7.1% in females and 10.1% in males during drought years. We also estimated that the temporary emigration rate was 19% (CI = 15.5% - 23.1%), indicating that about 1/5 of the super-population of painted turtles is outside the study pond at any given time. Our results indicate that drought negatively affects the survival of painted turtles even if a pond retains water throughout the drought period. Further study is necessary to determine the mechanism controlling this effect of drought on turtle survival