Influence of Heteromyid Rodents on Oryzopsis hymenoides Germination

Microhabitat use and seeds in cheek pouches were examined in four species of heteromyid rodent. Individuals of each species were classified as male or female, resident or transient, and adult or juvenile. The following question is addressed: are there any differences in microhabitat use and seed collection within rodent species and are these differences associated with the sex, residence, or age of individuals? For microhabitats, there were significant differences among individuals for each species analyzed. However, these differences could not be attributed to sex, residence, or age groups within populations. In addition, there were no differences within rodent species in the variety or number of seeds contained in individual cheek pouches. In spite of apparent differences in microhabitat use among heteromyid species, individual rodents are extremely variable in their use of microhabitats.

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Computer-Simulation Analysis of Foraging by Heteromyid Rodents in Relation to Seed Distributions - Implications for Coexistence

Australian Journal of Zoology ◽

10.1071/zo9940467 ◽

1994 ◽

Vol 42 (4) ◽

pp. 467 ◽

Cited By ~ 5

Author(s):

OJ Reichman ◽

E Roberts

Keyword(s):

Computer Simulation ◽

Simulation Model ◽

Simulation Analysis ◽

Computer Simulation Model ◽

Foraging Patterns ◽

Uniform Distributions ◽

Naturally Occurring ◽

Sufficient Energy ◽

Heteromyid Rodents ◽

Seed Distribution

A number of hypotheses have been proposed to explain the mechanisms that promote coexistence among sympatric rodents in North American deserts. In an effort to determine how the distribution of seeds influences foraging patterns and coexistence in a three-species community of heteromyid rodents, we developed a computer simulation model that determines the efficiency of foraging for animals of different sizes. Specifically, the simulation determines how long it would take a forager to gather sufficient energy for 24 h if the animal stopped at seed patches of certain densities. The analyses were conducted for naturally occurring seed distributions and densities, for simulated normal and uniform distributions at natural densities, and for natural distributions at seed densities one-third those known to occur naturally. The results indicate that, under natural distributions and densities, each of the three species possessed unique optima for utilising seed patches of different density. However, when either the seed distribution or density differed from actual values, all three species had identical optima. The implications of these results for promoting coexistence are discussed.

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