Nesting in close quarters: causes and benefits of high-density nesting behaviour in Painted Turtles (Chrysemys picta)

Abstract

Many oviparous reptiles nest in aggregations and with temporal synchrony. We hypothesized that these traits reflect attraction by conspecifics rather than limiting suitable habitat. We quantified whether Painted Turtles (Chrysemys picta (Schneider, 1783)) in Algonquin Park, Ontario, were nesting communally, identified cues females used to select nest sites, and tested whether hatching success was higher in spatially-clustered nests. We found that nests were closer to one another than expected by chance (i.e., were clustered), but that individual nest site selection was only weakly influenced by micro-habitat characteristics. Survival of clustered nests (49%) was not significantly higher than that of solitary nests (39%). When turtle models were placed on the nesting embankment, females nested most often with the highest density of models. Given that reproductive lifespan is the major axis of fitness and that there was little benefit to nest survival in clustered nests, we suggest that clustering is related to females cueing to conspecific nests to expedite the nesting process and gain a good-quality nest site (chosen by the first nesting female in the cluster) while investing little energy in nest-site selection. This strategy may reduce time spent on land, thereby minimizing chances of dehydration, temperature stress, and adult depredation.

Creating landscape‐appropriate habitat restoration strategies: success of a novel nesting habitat design for imperiled freshwater turtles

“…High nest density or communal nesting sites have been found to have high depredation rates (Petokas & Alexander 1980; Marchand & Litvaitis 2004; Riley & Litzgus 2014). Although some research suggests communal nesting may reduce predation rates (Robinson & Bider 1988), Kell et al (2022) found that survivorship of high‐density nests was only about 10% higher than solitary nests whereas Burke et al (1998) found no relationship between predation rate and nest density. This variability is likely because many factors can influence nest predation rate, including anthropogenic disturbances (e.g.…”