Nesting stage and distance to refuge influence terrestrial nesting behavior of Painted Turtles (Chrysemys picta)

Abstract

Theory predicts prey should flee to safety when the fitness benefits of flight meet or exceed the costs. Empirical work has shown the importance of predation risk (e.g., predator behavior, distance to refuge) to prey flight behavior. However, less is known about the influence of flight costs. We monitored nesting Painted Turtles (Chrysemys picta (Schneider, 1783)) to examine their response to a human observer (potential predator) depending on the distance between a turtle and an observer, distance between a turtle and water (i.e., refuge), and nesting stage at the time of the encounter (i.e., searching for a nest site vs. constructing a nest). We found no evidence that the distance to an observer influenced flight decisions. However, turtles were less likely to flee as the distance to water increased, and turtles already constructing nests were more likely to continue nesting than those still searching for nest sites. Turtles that traveled farther from water and that were constructing nests may have continued nesting because they had invested considerable energy and were close to completing oviposition. Thus, the fitness benefits of being closer to successful oviposition may outweigh the costs of increased vulnerability to predators during this important and vulnerable period of reproduction.

Mother knows best: nest-site choice homogenizes embryo thermal environments among populations in a widespread ectotherm

“…Thus, the ultimate advantages for nest-site choice vary among taxa (and even among populations) and are not necessarily mutually exclusive. As we show, choice of nest sites in wild C. picta minimally involves buffering embryos from experiencing current temperature-induced selection, along with maternal manipulation of offspring sex ratios [ 28 ] and other offspring traits [ 18 , 29 ], but probably not nest depth [ 86 ] or maternal predation risk [ 93 ]. Nest site choice might serve as an important mechanism by which some organisms could at least partially mitigate the effects of rapidly changing environmental conditions (reviewed in [ 7 ]).…”

Age Predicts Risky Investment Better Than Residual Reproductive Value

“…We then compared them among each other and with age to test which better predicts how far female C. picta construct nests from water. Nest distance to water is an important investment measure because maternal risk should increase the farther females travel from the safety of water (discussed in Delaney et al 2017;Delaney and Janzen 2020). In contrast, embryos in nests constructed farther from water experience lower predation rates because nest predators tend to forage along the shore (e.g., Kolbe and Janzen 2002;Spencer 2002;Strickland et al 2010).…”