The feeding pattern of the Norway rat (Rattus norvegicus) in two differently structured habitats on a farm

The adaptation of bait uptake behaviour in Norway rats (Rattus norvegicus) to the conditions of particular habitats was investigated on a farm in north-west Germany. Live-trapped rats were fitted with individual PIT tags and were automatically registered at bait stations in two differently structured habitats within the farm buildings. One bait station was installed in the pigsty, a habitat characterised by frequent disturbance and a limited food supply. The other bait station was located on the grain floor, a habitat with low disturbance and stable food supply. Circadian activity, social interactions and the amount of food uptake per individual visit were analysed using video recordings of rat activity at the bait stations. In contrast to the grain floor, where rats were strictly nocturnal, rats in the pigsty were also active during daytime, particularly during the farmer's breaks. They visited the bait station more frequently, spent more time and took more bait at a higher feeding rate than on the grain floor. Encounters with conspecifics at the bait station in the pigsty tended to be more aggressive while on the grain floor defensive attitudes prevailed. In both habitats, females showed higher feeding speed and bait uptake than males. Our results suggest that rats show distinct adaptations to diverse habitat conditions, resulting in behavioural differences among rat colonies even on a small scale within a single farmstead. They will assist in developing more effective strategies for rat control. (c) 2005 Elsevier B.V. All rights reserved.