Home range and movement in populations of Rattus norvegicus polymorphic for warfarin resistance

Abstract

Movements of brown rats were deduced from records made during a capture-recapture study of rural populations on two farms in Mid-Wales. Populations in the hedges were sampled at monthly intervals for two years, but samples from the farm buildings were obtained only irregularly and by a variety of methods.On the main trap line, of the rats captured during at least two sampling periods 35 (78%) females and 57 (74%) males appeared to have established home ranges, the best estimates of mean home range length for each sex being 54.8 m and 66.1 m respectively. The longest recorded distances travelled during known life were 850 m for a female and 954 m for a male, although the median distances travelled were only 43 m and 52 m respectively. The median distance travelled during a sampling period (seven nights) was about 24 m for both sexes. There were no significant differences between the distances travelled by the sexes or by different age groups, and there was little seasonal variation.Infestations in the hedges were always associated with streams, and those more than about 100 m from the buildings seldom persisted through winter. During autumn and winter the rats in the more distant localities tended to move towards the buildings, but there was no suggestion of an orderly migration. Twenty-seven out of 386 rats marked in the hedges were recovered amongst 576 taken from the buildings, but only nine of them had travelled more than 100 m. No rats released in the buildings were captured in the hedges. Rats established in the buildings seemed to exclude rats immigrating from the hedges.

Rat ranges in arable areas

“…Other studies (e.g. Aisenstadt, 1945;Emlen, Stokes & Winsor, 1948;Zapletal, 1964;Hartley & Bishop, 1979;Huson & Rennison, 1981;Brodie, 1981;Homolka, 1983) show that hedges and fields are marginal habitats for rats, except when crops are available for food.…”

Notes from the Mammal Society—No. 48

“…It is widely believed that Norway rats tend to migrate seasonally, from the fields into farm buildings in the early winter and in the opposite direction in the spring (Huson & Rennison, 1981). It is also known that males generally move greater distances and change their home-sites more frequently than females (Taylor, 1978;Hartley & Bishop, 1979). A report by Calhoun (1962), studying a population of rats in a large outdoor enclosure, is of particular interest in suggesting a mechanism by which a sex difference in migration could arise.…”

The role of rodents in avian influenza outbreaks in poultry farms: a review

“…Evidence suggests that once a rat population has made a particular shed its domain, other rats may be deterred from entering. Two reports state that rural rats living in hedges, seldom enter nearby farm buildings, even during periods of food shortage, most probably because the rat population in the farm buildings deter this (Taylor 1978;Hartley & Bishop 1979).…”

“…Brown rats disperse from their natal burrows during adolescence, males travelling larger distances than females (Lynn & Brown 2009). They regularly cover distances of up to 500 m over open ground to food sources, and the greatest recorded distance during the known life of rats in a capture-release study over two years was just under 1 km (Hartley & Bishop 1979). Brown rats also move their home sites about once every 7-14 days, enabling a population to spread gradually over a larger distance (Taylor 1978).…”