Impact momentum and clamping force thresholds for developing standards for possum kill traps

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Abstract
Increasing public concern over inhumane trapping for pest control has created a need for standards to provide guidelines for trap developers, and to allow evaluation of whether the traps available are acceptably humane. A trap simulator was constructed to deliver predetermined impact momentum and clamping forces to anaesthetised possums. Using this device, we established the minimum impact momentum (kg.m.s‐1) and clamping force (new‐tons, N) required to render possums irreversibly unconscious within 3 min. The impact momentum required (7.5 kg.rn.s‐1) was considerably higher than that generated by the traps available in New Zealand (0.5–1.5 kg.m.s‐1). However, some currently available kill traps can deliver clamping forces sufficient to achieve irreversible unconsciousness within 3 min, provided the trap strikes the neck. Clamping threshold forces for neck captures (100 N) were about one‐third of that necessary for a head capture (367 N). The development of specific kill thresholds will allow trap developers to optimise their trap design by using the most efficient and mechanically attainable mix of impact and clamping components. Furthermore, these specifications could be used in standard procedures for assessing and screening traps before they are approved for use.