Premium
Microhabitat Utilization and Foraging Behavior of Bipedal and Quadrupedal Hetermoyid Rodents
Author(s) -
Thompson Steven D.
Publication year - 1982
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1938858
Subject(s) - foraging , ecology , biology , shrub , predation , torpor , nectar , insectivore , pollen , thermoregulation
Direct observations of free—living individuals were employed to quantify foraging behavior in Dipodomys deserti, D. merriami, and Perognathus longimembris in two Mojave Desert communities. D. merriami and P. longimembris do not partition shrub and open microhabitats, and all three species concentrate their foraging efforts (>75%) near or beneath the canopies of desert shrubs. Results of livetrapping assessments of microhabitat usage (conducted concurrently with foraging observations) resemble those of earlier studies but differ greatly from observational data; trapping may not produce accurate representations of spatial utilization. P. longimembris avoids open areas and utilizes shrubs in a relatively coarse—grained fashion. D. merriami and D. deserti frequently traverse open areas at high speeds and hence utilize shrubs in a relatively fine—grained manner. Beneath shrubs, D. merriami and D. deserti are more active and discrete in their foraging than is P. longimembris; both Dipodomys apparently search for large clumps of seeds, while P. longimembris forages slowly and continuously, taking individual seeds from scattered dispersions. The distinctive morphology of Dipodomys is interpreted as an adaptation that allows fine—grained use of desert shrubs in the face of high predation risk during intershrub transits. Differences in heteromyid body sizes may also reflect two foraging strategies: small size would reduce energy demands, and thus lower the need to move between shrubs and reduce the need for predator avoidance; larger size would permit year—round activity (avoidance of torpor), reduce susceptibility to starvation (B. K. McNab, personal communication), increase the range of thermal tolerance, and generally increase abilities to cope with variations in environmental parameters (Boyce 1978). It is concluded that the morphological and behavioral differences between Dipodomys and Perognathus reflect divergent foraging strategies which may reflect equivalent but alternative strategies for exploitation of desert seeds.