Population cycles and outbreaks of small rodents: ten essential questions we still need to solve
AbstractMost small rodent populations in the world have fascinating population dynamics. In the northern hemisphere, voles and lemmings tend to show population cycles with regular fluctuations in numbers. In the southern hemisphere, small rodents tend to have large amplitude outbreaks with less regular intervals. In the light of vast research and debate over almost a century, we here discuss the driving forces of these different rodent population dynamics. We highlight ten questions directly related to the various characteristics of relevant populations and ecosystems that still need to be answered. This overview is not intended as a complete list of questions but rather focuses on the most…
Who eats first? Uptake of pellet bait by target and non-target species
House mice (Mus domesticus) are an important vertebrate pest in Australian agriculture. We studied the uptake of non-toxic placebo bait pellets targeted on house mice from bait stations in the grain-growing region of southeastern Australia. Bait stations allowed access for either ants; ants and mice or ants, mice, and birds. Soy meal bait pellets offered in December were of low preference for both ants and mice, but were eaten by birds in one study plot. In January, there were no differences between bait stations in the amount of wheat bait pellets removed indicating that the pellet bait had been primarily removed by ants. Most pellet bait was removed during the first 12 h after distributio…
Is the reproductive potential of wild house mice regulated by extrinsic or intrinsic factors?
The regulation of reproductive performance in small mammals may be determined by extrinsic or intrinsic parameters. In a large-scale, replicated field experiment we monitored the seasonal fluctuation in food availability and tested the effects of food addition on the reproductive performance of wild house mice (Mus domesticus) in south-eastern Australia. Ovulation rates and litter size increased during spring and peaked in October/November. Ovulation rate was consistently higher than litter size by approximately 1.2 embryos (19%). None of the extrinsic parameters measured (food quality and quantity, mouse abundance) had an impact on reproductive performance. The addition of food did not pre…
Predation risk and habitat selection of Australian house mice , Mus domesticus , during an incipient plague: desperate behaviour due to food depletion
We studied habitat selection and foraging behaviour of the house mouse (Mus domesticus) related to increasing mouse densities and depleting food resources over the breeding season. The study was conducted during the increase phase of an incipient outbreak of mice in a grain-growing area of southeastern Australia. A 3-year rotation created a mosaic of large paddocks of grain crop, pasture, and fallow. The narrow fence lines between paddocks provide an important stable habitat for the mice. We monitored population densities with live-trapping and habitat preference by measuring giving-up densities (GUD) using artificial food patches. Food patches were established in crop fields, fence lines, …