Behavioral Interactions Among Four Species of the Salamander Genus Desmognathus

Abstract

Four sympatric species: Desmognathus quadramaculatus, D. monticola, D. fuscus, and D. ochrophaeus, showed different substrate preferences in experimental trials. In addition, the choices of substrates and of cover objects were influenced by the presence of other salamanders. Significant differences in substrate choice were found for each pair of species. The ratio of rocky to woody substrate chosen was lower for the more terrestrial species. The ecologically intermediate species, D. monticola, exhibited the broadest choice of substrate and shifted its choice when confined with congeners. Adults of D. monticola became more active and avoided the preferred substrate of D. quadramaculatus when confined with that species. Juveniles of D. monticola became less active but also avoided preferred substrates of the larger D. quadramaculatus. In 1-m 2 arenas with four cover objects, small individuals of the three more terrestrial species avoided cover occupied by large individuals of these species. No aggressive behavior patterns were observed in 100 encounters of different individuals. These results suggest that this assemblage of salamanders is structured by species-specific microenvironmental preferences that are affected by interspecific interactions. Avoidance of other salamanders is the common response that segregates individuals and species. This avoidance is likely an adaptation to the severe risk of predation faced by small salamanders.

Abiotic factors influencing abundance and microhabitat use of stream salamanders in southern Appalachian forests

“…In eastern United States forests, salamanders typically comprise the greatest biomass of any vertebrates (Burton and Likens, 1975;Petranka and Murray, 2001;Peterman et al, 2008) and serve a key role in the ecosystem because they consume invertebrates and serve as prey for other vertebrates. While numerous studies have documented the importance of competition and predation in structuring stream salamander assemblages and their distributions (e.g., Southerland, 1986b;Hairston, 1987;Roudebush and Taylor, 1987), relatively fewer studies have examined the importance of environmental factors in undisturbed habitats. Of these studies, Keen (1984) found that dusky salamanders (Desmognathus fuscus) were found under smaller rocks more frequently on high moisture than low moisture substrates.…”

“…Eastern red-backed salamanders (P. cinereus), which were presumably superior competitors, inhabited isolated pockets were soil moisture was higher and forced the Shenandoah salamanders (P. shenandoah) to reside in the much drier talus slopes. In the southern Appalachians, Southerland (1986b) found that the larger black-bellied salamanders (D. quadramaculatus) predation of juvenile seal salamanders (D. monticola) sharply reduced survival and caused shifts in activity and habitat selection. In the 149 plots that we encountered stream salamanders, only 11 of these plots had salamanders of two or more species.…”

Evidence for asymmetric competition among headwater stream vertebrates

“…It is also possible that creek chubs actively interfere with salamanders to prevent access to resources via aggressive encounters. Aggression has been observed between spring salamanders and brook trout (Resetarits, 1991), and Desmognathus salamanders will avoid habitats to reduce the potential of negative interactions with more aggressive salamander species (Southerland, 1986a). Our study did not allow us to evaluate which mode of competition is responsible because we did not make systematic observations to quantify aggressive behaviors, an area of focus for our future research.…”

Out of the frying pan into the fire: an ecological perspective on evolutionary reversal in life history in plethodontid salamanders (Amphibia: Plethodontidae)

“…This result was interpreted as a non-lethal behavioral response to a predator. Southerland (1986a) conducted substrate choice and refuge sharing experiments in an ensemble of four desmognathans, D. quadramaculatus, D. monticola, D. fuscus, and D. orestes. He reported shifts in habitat choice in response to congeners, which varied according to species and body size.…”