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The advent of 'conservation agriculture' (CA) farming using zero- or no-tillage practices and an accompanying change in crop rotations in the last 10–15 years has potentially led to less disturbance of mouse burrows and increased cover and food supply. Given the irregular outbreaks of mice in grain cropping regions in Australia and the damage they cause, it is important to understand when and where mouse populations increase so that management strategies can be improved. We utilised a 20-year long-term mouse population data set collected prior to the introduction of CA farming practices and a more recent 8-year data set after CA to compare changes in mouse population abundance in a typical dryland grain cropping system in north-western Victoria, Australia. Mouse trapping data were used to compare abundance in crop and margin habitats during crop growth and non-crop (fallow) periods before ('conventional') and after introduction of CA. Mice are now resident year-round within crops and stubble and appear to only spill over into margin habitats. Previously developed recommendations for mouse management that include their control while in margin habitats may no longer be valid. [ABSTRACT FROM AUTHOR]

1. Outbreaks of feral house mice, Mus domesticus, in Australia represent a fundamental failure of the behavioural control mechanisms of population density, as proposed in the hypothesis of self-regulation. 2. Mice have the potential to keep numbers in check via a suite of spacing behaviours; however, the self-regulation hypothesis implies that some social change occurs that permits the population to erupt. It also suggests that at different phases of an outbreak, distinct patterns of social activity are evident. 3. We compare predictions from two models encapsulating the self-regulation hypothesis as applied to feral house mice in south-eastern Australia. Each model may be distinguished by the timing of aggressiveness between mice that leads to a closed social system. We compare individual turnover, residency and territoriality in each sex and age cohort during the increase, peak and low phases of a population outbreak that peaked in 2001. 4. The activity of 438 mice was monitored via intensive mark–recapture trapping and an automated event recording system that detected the activity of 300 marked individuals at burrow entrances. 5. Our findings support the second model, which suggests that mice switch from an almost asocial structure at low densities to a territorial system as abundance increases. Adult females appear more likely than males or juveniles to make the significant social shift. The trigger for this change remains unclear and several alternative mechanisms are proposed. [ABSTRACT FROM AUTHOR]

Populations of feral house mice ( Mus domesticus L.) in Australia undergo multiannual fluctuations in density, and these outbreaks may be partly driven by some change in behavioural self-regulation. In other vertebrate populations with multiannual fluctuations, changes in kin structure have been proposed as a causal mechanism for changes in spacing behaviour, which consequently result in density fluctuations. We tested the predictions of two alternative conceptual models based on kin selection in a population of house mice during such an outbreak. Both published models ( ; ) propose that the level of relatedness between interacting individuals affects their behavioural response and that this changes with population density, though the nature of this relationship differs between the two models. Neither of the models was consistent with all observed changes in relatedness between interacting female mice; however, our results suggested that changes in kin structure still have potential for explaining why mouse outbreaks begin. Therefore, we have developed a variant of one of these conceptual models suggesting that the maintenance of female kin groups through the preceding winter significantly improves recruitment during the subsequent breeding season, and is therefore necessary for mouse outbreaks. We provide six testable predictions to falsify this hypothesis. [ABSTRACT FROM AUTHOR]

Presents a study that compared the actual abundance of confined populations of wild house mice with closed population estimates in Australia. Methodology of the study; Demonstration of the presence of heterogeneity in mice trappability; Performance of Chao's modified moment estimator in the study.

Summary 1. Mouse plagues are a significant problem to agricultural areas of Australia, causing millions of dollars of damage. This study was conducted to determine if rainfall could explain the occurrence of mouse plagues. 2. On average, data on mouse abundance were collected every month, using mark-release-recapture techniques, from the Victorian Mallee cereal-growing region, from February 1983 to October 1994. No data were collected from December 1990 to September 1992. Three plagues of mice occurred during these 12 years. We examined the rate of increase of mouse populations as a function of antecedent rainfall. 3. The highest observed rate of increase per month was during 1986 (r = 1·86). The highest observed rate of decrease per month was during 1984 (r = –2·85). The maximum rate of increase of mouse populations used in the numerical response function was 1·16 month–1. The best estimate for the numerical response function was robs = –6·79 + 7·95 (1 – e–1·11V). 4. The numerical response of mouse populations to rainfall was examined against 6-month accumulated rainfall that was lagged by 0, 3 and 6 months. The best fit of the model was to lag rainfall by 3 months. 5. Two systems for the response of mouse populations to rainfall are described. The plague system occurred when mouse populations responded to rainfall: populations increased following high rainfall and decreased following low rainfall. The non-plague system occurred when the exponential rate of increase and rainfall were independent: populations crashed after a plague and were unable to respond to rainfall for at least 2 years thereafter. 6. The two systems suggest that there is ‘biological memory’ that masks the effect of rainfall for a minimum period after a mouse plague. This memory appears to be associated with the time since the last plague, the population response by mice (including... [ABSTRACT FROM AUTHOR]