Do Behavioral Interactions between Salamanders and Beetles Indicate a Guild Relationship?

• Published in: The American midland naturalist Vol. 149; no. 2; pp. 363 - 374
• Main Authors: GALL, STEPHANIE B, ANTHONY, CARL D, WICKNICK, JILL A
• Format: Journal Article
• Language: English
• Published: Notre Dame University of Notre Dame 01.04.2003; American Midland Naturalist
• Subjects: Animal behavior; Beetles; Biological taxonomies; Contents; Ecological competition; Experimentation; Forest litter; Insect behavior; Insects; Predation; Predators; Reptiles & amphibians; Salamanders; Secretion
• ISSN: 0003-0031; 1938-4238
• DOI: 10.1674/0003-0031(2003)149[0363:DBIBSA]2.0.CO;2

Guilds consist of groups of species that use mutual resources or collections of overlapping resources. Guilds are often comprised of members of the same family or genus, but they can span larger taxonomic categories. Predacious arthropods, such as carabid beetles, centipedes and spiders, and small carnivorous vertebrates, such as woodland salamanders, overlap extensively in microhabitat and prey types. These taxa, though unrelated, may form important guilds of forest floor predators. We examined the behavioral interactions between a carabid ground beetle (Platynus tenuicollis) and a small woodland salamander (the red-backed salamander, Plethodon cinereus) in laboratory encounters. These species occur syntopically and feed on similar prey. Individuals of P. cinereus are territorial and defend cover objects against conspecific and congeneric intruders. Because both species require moist conditions, it seems probable that they would compete for resources, such as cover objects and prey, as the forest floor and leaf litter dries. We posed two general hypotheses: (1) salamanders will display territorial behavior toward intruding salamanders and beetles and (2) beetles will display territorial behavior toward intruding beetles and salamanders. Residents of each species were paired with control, intra- and interspecific intruders. In both species, residency status affected behavior—residents behaving more aggressively than intruders. Resident salamanders behaved similarly toward intruding salamanders and beetles, but no biting was observed. There were no significant differences in aggressive behavior of resident beetles among treatments. When physical attacks by beetles were observed, they were brief and often escalated to biting and chasing. Platynus tenuicollis bit intruders of both species in a significant number of trials; this often resulted in the production of adhesive secretions by P. cinereus that successfully immobilized P. tenuicollis. Antipredator behaviors observed in P. cinereus, and biting by P. tenuicollis of P. cinereus, suggest that intraguild predation may be as important as interspecific resource competition for these species of forest floor predators.