Are life history strategies of Norway rats (Rattus norvegicus) and house mice (Mus musculus) dependent on environmental characteristics?

VADELL, VICTORIA; GÓMEZ VILLAFAÑE, ISABEL; CAVIA, REGINO

WILDLIFE RESEARCH

CSIRO PUBLISHING

Lugar: Collingwood; Año: 2014 vol. 41 p. 172 - 184

1035-3712

Context: Life history theory attempts to explain the way in which an organism is adapted to its environment as well as explaining the differences in life history strategies among and within species. The aim of this paper was to compare life history traits of the Norway rat and the house mouse living in different habitats and geographic regions in order to find patterns related to environmental characteristics based on published ecological studies conducted before 2011. The environments where rodent populations lived were characterized according to climate type, occurrence of freezing temperatures and frost, degree of anthropization and trapping location. Four demographic characteristics were analysed. A Canonical Correspondence Analysis was performed to explain the effects of environmental variables on the demographic characteristics of rodents. Information was gathered from 35 articles published between 1945 and 2010. Most populations of both species showed differences in abundance through out the year but no defined pattern was common among populations. The pregnancy rate of Norway rat was highest during spring and autumn in urban environments, during spring and winter in rural environments and during summer in sylvan habitats. House mouse populations were most frequently reported to experience high pregnancy rates during summer. Contrary to urban and rural populations, in sylvan environments the occurrence of a reproductive break was the most commonly reported pattern for both species. Litter size of Norway rat depended on the degree of anthropization and the occurrence of freezing temperatures and frost. Litter size was greater in rural environments and in areas without freezing temperatures and frost. House mouse did not show differences in litter size resulting from any of the environmental characteristics analyzed. Both species are able to modify their reproductive strategies according to environmental characteristics, especially according to the degree of anthropization of the environment. In sylvan areas, where animals are more exposed to seasonal changes in weather conditions, changes in reproductive investment are more evident. Regarding the implications for rodent control, the best time to apply control measures could be winter in sylvan and urban environments. In rural environments the best time for conducting control efforts is less clear, though cold seasons seem also to be the best.