Nest, but Not Egg, Fidelity in a Territorial Salamander

Abstract

Egg recognition and subsequent egg brooding are costly forms of parental investment in many species of vertebrates. Life history factors, such as coloniality or risk of brood parasitism, may constrain egg recognition in vertebrates. Female red‐backed salamanders (Plethodon cinereus) from my study site are territorial and do not share nest sites with other females. They are terrestrial and neither they nor their eggs are likely to be displaced by environmental factors such as flooding. I experimentally tested, in the laboratory, the hypothesis that female red‐backed salamanders can discriminate between their own eggs and the eggs of unfamiliar females. Each female was allowed to move about a test chamber containing two clutches of eggs, one clutch with which it was found in the forest and one that had been found with a distant female. Most females remained with one clutch of eggs, which they brooded during the entire observation period. However, they did not significantly prefer to brood their own eggs over the eggs of another female. In a corollary field experiment, I tested whether brooding females that were displaced 1 m from their nest sites would return to their territories and commence brooding behaviour within 3 d. All 10 displaced females returned to their own nest within this time period and were found brooding their eggs. Because female red‐backed salamanders at my study site do not tend to share nest sites with other females and because their eggs remain in stationary nests, selection may not have favoured egg recognition. However, the results suggest that female salamanders indirectly recognize their own eggs by actively recognizing their territorial nest sites.

Does maternal care evolve through egg recognition or directed territoriality?

“…Parental‐caring animals should have mechanisms through which to locate their eggs if they become separated from them (Peterson, 2000). Despite foraging outside of the nest during the extended period of parental care (up to 35 days; Huang, 2007), nest‐guarding long‐tailed skinks cannot recognize their own eggs.…”

“…Despite foraging outside of the nest during the extended period of parental care (up to 35 days; Huang, 2007), nest‐guarding long‐tailed skinks cannot recognize their own eggs. Peterson (2000) suggested that if the probability of confusing a neighbour’s nest for one’s own nest is small, then indirect nest recognition mechanisms are favoured; but if nests are aggregated or difficult to identify based on environmental cues, direct egg recognition mechanisms are favoured. For example, red‐backed salamanders ( Plethodon cinereus ) cannot discriminate between their own eggs and those of unfamiliar females but can relocate experimentally displaced nest sites (Peterson, 2000).…”

“…Peterson (2000) suggested that if the probability of confusing a neighbour’s nest for one’s own nest is small, then indirect nest recognition mechanisms are favoured; but if nests are aggregated or difficult to identify based on environmental cues, direct egg recognition mechanisms are favoured. For example, red‐backed salamanders ( Plethodon cinereus ) cannot discriminate between their own eggs and those of unfamiliar females but can relocate experimentally displaced nest sites (Peterson, 2000). Although that situation may be rare in nature, it provides evidence of indirect nest‐site recognition, rather than direct egg recognition (Vitt & Cooper, 1989).…”

Nest and Egg Recognition by Salamanders in the Genus Desmognathus: A Comprehensive Re‐Examination

“…In short, females are infrequently displaced, and when they return to their nesting cavity they are not forced to choose between their own and conspecific eggs. As a consequence, egg discrimination does not appear to have evolved in woodland plethodontids (Peterson 2000). The behavioral differences we observed in Desmognathus are more problematic.…”

“…These broad generalizations were challenged by Peterson (2000) who demonstrated that female Redback Salamanders ( Plethodon cinereus ) exhibit nest, but not egg fidelity. In light of her carefully controlled experiments, we acknowledge that egg recognition may not be ubiquitous among plethodontid salamanders, and we feel that it is time for a comprehensive re‐examination of homing to the nest and egg recognition in Desmognathus .…”