Intraspecific Predation and Habitat Use by Tiger Salamanders (Ambystoma tigrinum nebulosum)

Abstract

the risk of intraspecific predation influences spatial and temporal patterns of habitat use by smaller conspecifics (Fraser and Cerri, 1982; Sih, 1982). In this study I test whether smaller tiger salamander larvae, Ambystoma tigrinum nebulosum, will alter their pattern of habitat use in the laboratory in response to the presence of larger conspecific predators. I have already shown that larvae alter their diel pattern of habitat use in nature to minimize encounters with interspecific predators (Holomuzki, 1986). However, larvae of some populations may also encounter intraspecific predators. Two gilled morphs, cannibalistic and typical, can occur within the same population of A. t. nebulosum (Gehlbach, 1967a, b; Collins, 1981). Cannibalistic morphs have broader heads and larger vomerine teeth than do typical morphs. Cannibalistic morphs eat mostly other salamanders, whereas the latter eat primarily zooplankton (Dodson and Dodson, 1971; Collins and Holomuzki, 1984). However, cannibalism by secondyear typicals can eliminate small first-year larvae from some populations when the age classes overlap (Burger, 1950). This paper examines if the presence of second-year cannibalistic and secondyear typical morphs affects habitat use of firstyear typical larvae. Salamanders were seined from Lower Cotton-