What Are the Primary Cues Used by Mammalian Predators to Locate Freshwater Turtle Nests? A Critical Review of the Evidence

Abstract

Turtle biologists have long been interested in the biotic and abiotic factors that influence the detection of freshwater turtle nests by mammalian predators. Increased knowledge of nest predation dynamics may help develop conservation strategies to increase turtle nesting success by altering or reducing the signal strength of predominant nest location cues. However, despite this long-standing interest, the related research has produced inconsistent and sometimes conflicting results across studies. Here we review much of the existing literature on freshwater turtle nest predation by mammalian predators and attempt to synthesize some general, underlying themes. Available data suggest that raccoons (Procyon lotor) primarily use olfactory cues associated with nest cavity construction to locate turtle nests. However, some other predators, including red foxes (Vulpes vulpes) and other canids, may commonly use a wider array of cues, including scents from nesting turtles and their eggs as well as visual cues, while foraging. The literature also suggests that the length of the period turtle nests remain vulnerable to nest predation is dependent on the predator community, with raccoons exhibiting relatively short timelines relative to some other predators, including canids. This review has revealed a strong North American bias in published work, highlighting the need for additional studies of turtle nest predation dynamics in other areas of the world where chelonians are often imperiled elements of the biota.