Thesis (M.S.)--Oregon State University, 1966. / Typescript (Photocopy). Includes bibliographical references (p. 218-221). Also available via the World Wide Web.

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Small mammal population dynamics and community structure were studied in three East Central Florida communities. The communities were compared as distinct stages of a sand pine scrub sere. The small mammals live-trapped with greatest frequency in this 3852 trap-night study were all cricetine rodents, Peromyscus polionotus niveiventris (beach mouse), Sigmodon hispidus littoralis (cotton rat), and Peromyscus gossypinus palmarius (cotton mouse). Population numbers, survival, body weights, hind foot lengths, age structure, sex ratios, reproductive cycles, and movements were discussed for each of three species mentioned. These data will serve as a baseline information for ecological monitoring studies associated with NASA Space Shuttle operations. Small mammal community structure was examined with regard to interspecific spatial overlap and body size ratios. Vegetation density was compared within and among the study sites. Within study sites vegetation density appeared to influence mammal microhabitat selection. Among study sites a highly significant correlation was found between small mammal species diversity and vegetation density.

Laboratory experiments have suggested that the coexistence of certain heteromyid rodent species is facilitated through differential use of seed dispersions (clump sizes). Field experiments with the Bannertail kangaroo rat, Dipodomys spectabilis, and Merriam's kangaroo rat, D. merriami, indicate their use of different clump sizes is not sufficiently specialized to permit coexistence. Field experiments based on the assumption that these species interact primarily through aggression demonstrated that during at least one season of the year D. spectabilis excludes the smaller D. merriami from its foraging range. Preliminary characterization of spatial heterogeneity of resource productivity implies that the competitive coexistence of these species is regional and is dependent upon the existence of areas with low productivity that are not economically usable by D. spectabilis. These areas of low productivity may serve as a competitive refuge for D. merriami, facilitating its persistence. A brief review of the evidence for the occurrence of competition between heteromyid species is presented, as is a selected review of the evidence supporting the various hypotheses explaining the competitive coexistence of heteromyid rodents.

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Thesis (M.S.) in Wildlife Ecology--University of Maine, 2009. / Includes vita. Includes bibliographical references (leaves 124-152).

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Demography of nocturnal desert rodents was monitored for nine years. Three dissimilar areas were sampled with three distinct trapping configurations and time regimes. All three areas contained similar rodent species. Increased plant growth and seed production resulting from variations in rainfall seemed to have the most profound effect on both rodent densities and species composition. Deviations from the bimodal rainfall pattern occurred in the latter parts of 1972, 1977, and 1978 and early 1973, 1978, and 1979. During these times there was a 2-4 fold increase in rainfall. This pattern produced "desert blooms" in the spring of 1973, 1978, and to some extent 1979. In addition, 1972 and 1978 were years of high rainfall. The reaction of the rodents to the increased plant production was rapid and dramatic. Heteromyid numbers increased approximately six fold with some species increasing twelve fold within a matter of five months. The smaller heteromyids, Perognathus amplus and P. penicillatus, were the first to increase substantially, while the larger rodents reached peak populations in the following year. The resulting population crash that followed the high densities was as dramatic as the increase. Neotoma albigula populations did not increase substantially after the first rainfall phenomenon but did so dramatically after the second period of aberrant rains. The densities of N. albigula remained high long after the heteromyid populations decreased to "normal" levels. The three areas were found to be dominated by different species while the overall rodent densities in the three areas were very similar within the same time frame.

I obtained densities of nocturnal rodents in the saguaro (Carnegiea gigantea) forest of Saguaro National Monument, Arizona with live trapping techniques, in 1984 and 1985. I sampled vegetation density, percent cover, and foliage height diversity. My objective was to determine if humans influenced nocturnal rodents and their habitat. Rodent populations and vegetation were analyzed through 2-way analysis of variance. Few significant differences were determined for rodent numbers between experimental and control plots. My findings show that minimal impact has occurred on rodent populations and on vegetation by humans in Saguaro National Monument.