We evaluated how American badgers (Taxidea taxus) might exert selective pressure on black-footed ferrets (Mustela nigripes) to develop antipredator defenses. In a colony of black-tailed prairie dogs (Cynomys ludovicianus) in South Dakota, badgers concentrated their activities where burrow openings and prairie dogs were abundant, a selective behavior that was exhibited by ferrets in the same colony. Badgers excavated burrows more often when in areas recently used by a ferret, suggesting that badgers hunt ferrets or steal prey from ferrets, or both. We also conducted an analysis of survival studies for ferrets and Siberian polecats (M. eversmanii) released onto prairie dog colonies. This polecat is the ferret’s ecological equivalent but evolved without a digging predator. Badgers accounted for 30.0% of predation on polecats and 5.5% of predation on ferrets. In contrast, both polecats and ferrets have evolutionary experience with canids, providing a plausible explanation for the similar relative impact of coyotes (Canis latrans) on them (65.0% and 67.1% of predation, respectively). We hypothesize that ferrets and badgers coexist because ferrets are superior at exploitation competition and are efficient at avoiding badgers, and badgers are superior at interference competition.
The effect of predators on the abundance of prey species is a topic of ongoing debate in ecology; the effect of snake predators on their prey has been less debated, as there exists a general consensus that snakes do not negatively influence the abundance of their prey. However, this viewpoint has not been adequately tested. We quantified the effect of brown treesnake (Boiga irregularis) predation on the abundance and size of lizards on Guam by contrasting lizards in two 1-ha treatment plots of secondary forest from which snakes had been removed and excluded vs. two 1-ha control plots in which snakes were monitored but not removed or excluded. We removed resident snakes from the treatment plots with snake traps and hand capture, and snake immigration into these plots was precluded by electrified snake barriers. Lizards were sampled in all plots quarterly for a year following snake elimination in the treatment plots. Following the completion of this experiment, we used total removal sampling to census lizards on a 100-m2 subsample of each plot. Results of systematic lizard population monitoring before and after snake removal suggest that the abundance of the skink, Carlia ailanpalai, increased substantially and the abundance of two species of gekkonids, Lepidodactylus lugubris and Hemidactylus frenatus, also increased on snake-free plots. No treatment effect was observed for the skink Emoia caeruleocauda. Mean snout–vent length of all lizard species only increased following snake removal in the treatment plots. The general increase in prey density and mean size was unexpected in light of the literature consensus that snakes do not control the abundance of their prey species. Our findings show that, at least where alternate predators are lacking, snakes may indeed affect prey populations.
Boiga irregularis (Brown Treesnake). Predation attempt by crab
Lardner, B., J.A. Savidge, T.J. Hinkle, E. Wostl, S.R. Siers, R.N. Reed, G.H. Rodda
The Coconut Crab (Birgus lacro) , also known as the Robber Crab, is the heaviest terrestrial invertebrate in the world with a mass occasionally exceeding 3 kg (Amesbury 19BO. UL1iv. Guam Tech. Rep. 17:1-39). While primarily an omnivore feeding on vegetative matter and scavenging for dead animals, it may also prey on live invertebrates and vertebrates such as sea turtle hatchlings and rats (Greenaway 2003. Mem. Mus. Victoria 60:13-26; Kessler 2005. Crustaceana 78:761-762)...
Boiga irregularis (Brown Treesnake). Predation attempt by praying mantis
The Western Pacific island of Guam is known for its introduced population of Boiga irregularis that has had considerable negative effects on vertebrates native to the island (Rodda et a!. 1997. BioScience 47:565-574; Savidge 1987. Ecology 68:660-668). Few animals in Guam are known to prey on the snakes, hut Mangrove Monitors (Varanus indict/s) and feral/domestic cats (Felis catus) may do so (Fritts and Rodda 1998. Annu. Rev. Ecol. Sys. 29:113-140; pers. obs.)…
Introduced Boiga irregularis on the Western Pacific island of Guam feed on a wide variety of vertebrate prey. Stomach contents of juvenile B. irregularis specimens include a large proportion of lizards, especially geckos and skinks (Savidge 1988. J. Herpetol. 22:275–282). Guam is also home to Varanus indicus (Mangrove Monitor), which reach an adult size of ca. 560 mm SVL (Wikramanayake and Dryden 1988. Herpetologica 44:338–344). Varanus indicus are opportunists that feed primarily on arthropods (Dryden 1965. Micronesica 2:72–76), but they may prey on B. irregularis (Fritts and Rodda 1998. Annu. Rev. Ecol. Sys. 29:113–140; McCoid and Witteman 1993. Herpetol. Rev. 24:105). Occasionally the roles are reversed and the snakes prey on monitor eggs (Savidge 1988, op. cit.), but in general, interactions between V. indicus and B. irregularis remain poorly documented…
Distribution and postbreeding environmental relationships of Northern Leopard Frogs (Rana Lithobates] Pipiens) in Washington