Date of this Version
Many eradication efforts to remove rats (Rattus spp.) from islands have been successful. Eradications are expensive and labor-intensive which makes early detection of, and response to, reinvasion by rats critical. A better understanding of rat behavior could facilitate early detection and rapid response to intercept invaders, such as with trap placement and design, and toxic bait presentation and dispersal. This was a methods development study of test paradigms to operantly condition wild rats to run on an activity wheel and to press a lever for use in future behavior studies. Operant conditioning is the process of associating specific responses with specific reinforcers. The purpose of this study was to estimate the timeframe needed to operantly condition rats on wheels and levers, and to develop ideal test paradigms for conditioning these responses. Results indicated that wild Norway rats (R. norvegicus) need about 14 sessions, including adaptation, to reach a steady-state performance on an FR 2 schedule in wheel trials. Rats may need at least 21 sessions to adapt and shape a lever-press response, and 7-14 additional sessions to optimize the response on an FR 1 schedule. Individual variation in activity levels and learning rates was observed, suggesting a complexity to predicting the behavior of invading rats.