Predator Responses to the Vermilion-Spotted Newt (Notophthalmus viridescens)

Abstract

Efts, adults and recently metamorphosed larvae of Notophthalmus viridescens were offered to a variety of potential predators, usually simultaneously or in alternating succes- sion with plethodontids and ambystomatids. Recently metamorphosed larvae were consistently refused by birds, usually refused by Thamnophis sirtalis, occasionally refused by Bufo ameri- canus, and usually eaten by Chrysemys picta and Chelydra serpentina. Efts were accepted and eaten by 3 of 5 Procyon lotor and by Rana catesbeiana but were refused by birds on sight, by Thamnophis sirtalis, and by 2 Procyon lotor. Adults were eaten by Rana catesbeiana but were refused by Thamnophis sirtalis and by birds. Chrysemys picta ate the ventral surface and viscera of dead adult N. viridescens but were reluctant to eat their dorsal surfaces, where poison glands are concentrated. The responses of predators are discussed in terms of the presumed aposematic (efts) and cryptic (adult) coloration of N. viridescens. * * * Newts used in these experiments were obtained in the Mount Pleasant-Ringwood area of Dryden, Tompkins County, New York. Post-larval migrants, including those of Ambystoma maculatum (Shaw) and A. jeffersonianum (Green), were caught by pit traps as they left ponds in the summer and fall (Hurlbert, in press). Efts were caught in the woods or by pit traps as they migrated to ponds in the fall (Hurlbert, 1969). In this region efts usually are very bright orange. Adults were caught in various ponds. Most plethodontids used in the experiments were caught in or near streams in Dryden and Ithaca, New York. Experimental procedures varied considerably and are described in detail as each set of re- sults is presented. Most experiments entailed presenting to the predator a newt and some other