Author:
Dickman C. R.,Mahon P. S.,Masters P.,Gibson D. F.
Abstract
Populations of rodents were studied for periods of 7−9 years at each of
three sites in arid Australia. All species fluctuated dramatically in
abundance, being absent or in low numbers during droughts but erupting after
significant rainfall. Strong correlations were obtained between capture rates
and cumulative monthly rainfall residuals, with time lags, that had been
modified by an exponential decay function to model the post-rain depletion of
resources. The introduced Mus domesticus erupted within
only two months of exceptional rainfall at one site, whereas the native
rodents Notomys alexis,
Pseudomys hermannsburgensis and
P. desertor generally responded 3Œ10 months after
rain. The faster response of M. domesticus reflects its
high reproductive potential compared with the native rodents, and perhaps
greater immigration. Differences in magnitudes and delays in response to
rainfall among the native species were due probably to differences in initial
population sizes and times available for response and, for
P. desertor, to between-site differences in the quality
or quantity of food resources. Population declines in all species during dry
periods probably followed resource shortages.
Despite the usually strong linkage between rainfall and population dynamics,
rain failed to trigger population responses in rodents for prolonged periods
at two of the sites, and was not clearly associated with an eruption of
P. hermannsburgensis at the third. The lack of a
population response at one site was attributed to predation, but events at the
other two remain unexplained. We conclude that long-term studies should play
an important role in describing temporal changes in rodent populations in arid
Australia and, with field experiments, in evaluating how rainfall and other
factors combine to effect the changes.
Subject
Management, Monitoring, Policy and Law,Ecology, Evolution, Behavior and Systematics
Cited by
173 articles.
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