Temporal Changes in a Chihuahuan Desert Rodent Community

Abstract

We used time series analysis of ten years of monthly census data to assess the responses of both individual species and an entire community of rodents to a fluctuating desert environment. Autocorrelation analysis revealed different patterns of intra-annual fluctuation among the It species: Dipodomys spectabilis and Perognathus Jarus had pronounced annual cycles: D. ordii, D. merriaini, Chaetodipus penicillutu~, Onvchomys torridus, 0 . leucogusrer, and Neotoma alhigula exhibited annual cycles modified by interannual variation; and Feromyscus eremicus, Pm. maniculatus, and Reithrodontornys megalofis showed little evidence of annual periodicity. The timing af annual cycles and the pattern of inter-annual fluctuations also differed among species. However. two results suggest that several species responded similarly to long-term environmental variation: 1)population densities of four species and total rodent biomass and numbers were positively correlated with the densities of annual plants; and 2) many pairs of species exhibited positively correlated population dynamics over the ten years, Clustering of painvise cross-correlation coefficients was used to identify sets of species with similar population dynamics. These clusters did not necessarily contain closely related or ecologically similar species. Detrended Correspondence Analysis identified three independent patterns of variation in species composition: a long-term trend; a four-to five-year repeated pattern that appeared to correspond to the climatic effects of the El Nifio Southern Oscillation: and an annual cycle. In general. species appeared to respond individualistically to environmental variation. There was no evidence of an equilibrium community composition or of alternative stable configurations, Some competing species had negatively correlated population dynamics, but the majority of competitors exhibited positive correlations that apparently reflected similar responses to fluctuating resources.

Population Dynamics of a Diverse Rodent Assemblage in Mixed Grass-Shrub Habitat, Southeastern Colorado, 1995–2000

“…We cannot say whether these different patterns in sympatric species evolved to minimize interspecific competition or as specializations for different resources independent of competitive pressures. Our results differ from those seen by Valone and Brown (1996) and Brown and Heske (1990) for many of the same species. Those authors found most associations to be positive, even among murid and heteromyid species, and concluded that general environmental conditions (as opposed to interspecific interactions) were of overriding importance in determining population dynamics.…”

Does a top‐predator provide an endangered rodent with refuge from an invasive mesopredator?

“…2, Table 2). The population dynamics of arid zone small mammals including N. fuscus typically increase in response to rainfall driven resource pulses (Brown & Heske, 1990;Meserve et al, 2003;Letnic et al, 2005;Moseby et al, 2006). In the present study, recent rainfall (Rain 6) and primary productivity were poor correlates of N. fuscus abundance.…”

Resilience and stability in bird guilds across tropical countryside

“…Third, many species, especially insectivores, form mutualistic mixed species flocks, traveling in concert in search of food (32). Over time, positive correlations in abundance may also arise because of common responses to abiotic factors (33)(34)(35). For example, because climate influences insect populations Fig.…”