The ontogeny of predatory behaviour in the golden hamster (M.a.auratus).
thesisposted on 19.11.2015, 08:57 by Richard Henry. Polsky
The treatise opens with a literature review on predatory behaviour in mammals. Areas discussed included species of investigation, methods of investigation, behavioural patterns, developmental and motivational aspects, the effect of hormones and the stimuli involved in the control of the response. A conclusion which emerged was that more research was needed with species other than the albino rat. This conclusion served as the impetus for experimentation on the ontogeny of predation in the golden hamster (M.a.auratus). In total, a pilot study, which focused on the qualitative aspects of the response, and 12 experiments were reported. The prey used throughout were nymphs of the species Locusta migratoria. The basic methodology consisted of introducing prey into a naive subject's own home cage and manually recording the following behaviours: latency to capture, and the frequency of prey exploration, withdrawal from the prey, nip at the prey and unsuccessful capture. The principal findings showed that: 1) older hamsters were more likely to capture; 2) with the experience of several successful captures hamsters became more efficient captors; 3) hamsters as young as 20 days would capture in the normal adult manner; 4) the interval between successive prey presentations had a small but significant effect on the likelihood of capture; 5) prey removal after capture decreased the chance of subsequent capture in hamsters with weak dispositions to capture; 6) prey removal after capture had no effect on hamsters with strong dispositions; 7) the response of capture could be 'primed' through prior sensory exposure to the prey; 8) prey-capture was susceptible to the effects of selective breeding. The theory ascribed to these results was that prey-capture in the hamster was a species-typical behaviour founded upon certain predispositions but nevertheless liable to the effects of experience. Therefore it was concluded: 1) for hamsters with weak dispositions to capture the pre-capture and post-capture experiences were both needed for the development of the response. The pre-capture phase (sensory exposure to prey and the performance of the behaviours involved in capture per se) served primarily to reduce fear and increase capture efficiency and the post-capture phase (prey consumption) served primarily to increase capture tendency; 2) for hamsters with strong dispositions to capture the development of predation was not dependent on eat after capture (the post-capture experience). This suggested that the pre-capture experience had self-reinforcing properties of its own. Hamster predation was then discussed from a comparative viewpoint and mention was made of areas in need of investigation.