Document: KUR-3-56-32

Antipredator behavior of the cave cricket (Hadenoecus subterraneus) in response to predation risk by white-footed mice (Peromyscus leucopus).

LEWIS HELF, K.* ¹, K.SCHMIDT ² and T.L.POULSON ¹

University of Illinois at Chicago, Chicago, IL 60607 USA ¹
University of Memphis, Memphis, TN 38152 USA ²

Abstract:
The cave cricket (Hadenoecus subterraneus) feeding in its natural habitat has been effectively used as a model system to investigate foraging strategies of crickets under the influence of predation risk and in response to other features of their abiotic and biotic environment. We qualitatively measured cricket foraging responses using color-coded baits positioned at increasing distance from cave entrances where crickets exit to forage on the surface, and quantitatively using the technique of giving-up fullness (GUF). The GUF represents the percent amount of food consumed by a cricket relative to its crop-empty live weight. We hypothesized that the degree to which crickets 'fill up' is proportional to their foraging costs, e.g., metabolic costs and predation risk. To test our hypotheses that crickets can assess and respond to the risk of predation from white-footed mice around cave entrances, we used a combination of GUF and tethering experiments. We tethered crickets outside three cave entrances to determine variation in predation rates among caves and variability in predation as a function of distance from a cave entrance. At the same time, GUFs were collected at distances of 0, 5, and 15m from entrances (distances identified by color-coded food). While our analysis showed cave entrance had a significant effect on GUFs (ANOVA, F_2,1036 = 3.25, P = .039), contrary to our predictions GUFs were highest (i.e. foraging costs lowest) at caves with the highest predation rates on tethered crickets. Though GUFs increased from 0 to 5m, consistent with our hypothesis of high density-dependent predation risk just outside cave entrances, predation rates on tethered crickets were not correlated with distance from cave entrances. Our data suggest crickets may not be responding primarily to the risk of predation while foraging outside of cave entrances. An alternative hypothesis is that resource competition is driving cricket behavior. Consistent with this hypothesis, we found: 1) A negative correlation between GUFs and the number of crickets feeding at our bait patches; and 2) shifts in habitat use (distance from entrance) as a function of the number of feeding crickets. Future studies will be directed at multiple explanations of cricket behavior.

Keywords: Predation Risk, Hadenoecus subterraneus, Peromyscus leucopus

This abstract is being presented at: 2:00 PM in session:
Oral Session #48: Anti-Predator Responses: Fish to Sagebrush.