Is reproduction of the Australian house mouse (Mus domesticus) constrained by food? A large-scale field experiment

Abstract

Food quantity and especially food quality are thought to be key factors driving reproductive changes in the house mouse, Mus domesticus, leading to outbreaks of house mouse populations in the Australian grain-growing region. Characteristic changes during an incipient mouse plague are an early start of breeding, a high proportion of females breeding at a young age and a prolonged breeding season. We conducted a large-scale food manipulation during an incipient mouse plague, which started with early breeding and relatively high spring numbers of mice. We measured background food availability in four farms throughout the study and conducted a food manipulation experiment from November to March in two of them. After harvest in December 100-200 kg/ha spilled grain remained in the stubble. This was depleted by March. In two treatment farms we added high-protein food pellets on a weekly basis between November and March and two farms served as controls. We measured changes in mouse numbers by capture-mark-recapture trappings and changes in reproduction by scoring embryos and recent placental scars at necropsy. Mouse numbers did not differ between treatments and controls. There were no differences in the litter size or the proportion of females breeding between treatments and controls. We observed the normal pattern of high litter size in spring and decreasing litter size towards the end of summer in treatments and controls. In all farms reproduction stopped in March. Mouse numbers were high but not at plague densities. Contrary to our prediction we did not observe food constraint affecting the reproduction of female mice. Our field experiment seems to rule out food quality as the driving factor for improved reproduction and formation of an outbreak of mice. We suggest that physiological mechanisms in mice might not enable them to take advantage of food with a high protein content in arid summers in southeastern Australian grain fields because of the lack of free-standing water.

Is quantity or quality of food influencing the reproduction of rice-field rats in the Philippines?

“…Food-supplementation experiments in rice fields (Bomford 1987a) and wheat croplands (Ylönen et al 2003) did not show a marked effect on the proportion of breeding female house mice. In the experiment of Bomford, food supplementation through artificial food stations did not significantly affect population abundance.…”

“…The food stations could have led to aggregation of mice and density-dependent effects could have influenced the breeding performance of female mice. The amount of food taken by mice was not measured in the later study (Ylönen et al 2003). There were spilled grains in both food-supplementation and control fields in their study.…”

“…Twenty 1-m 2 samples were selected inside the rice field and on the levee of the rice fields, by using systematic random sampling. The sampling was modified from a previous study developed for wheat fields in Australia (Ylönen et al 2003). If the soil was still moist and grains were immersed in the soil, then soil was removed to a depth of 50 mm and samples were placed into a cloth bag, along with any aboveground vegetation.…”

“…The quality of food can influence the reproductive ability of rodents (Negus and Pinter 1966;Reichman and Van De Graaff 1975;Bomford 1987a) and could be an important driver of high population densities in agricultural landscapes (Leirs et al 1994;Ylönen et al 2003). In South-east Asia, our understanding of the role of food quantity and quality on the population dynamics of rodents is less well understood, with only one study on Rattus argentiventer in An Giang province in the Mekong delta of Vietnam (My Phung et al 2011).…”

Breeding of house mice and the mast seeding of southern beeches in the Orongorongo Valley, New Zealand

“…This could apply equally in New Zealand beech forests. Some studies (e.g., Murphy 1992;White 2002) have stressed the importance of the protein content of seeds, but supplementary feeding experiments in Australia have been equivocal (e.g., Ylönen et al 2003). It seems to us that with substantial numbers of invertebrates in the usual diet of mice, protein content in the diet is unlikely to be so low that it limits breeding of mice.…”