Quantifying the nature and extent of native fauna by-catch during feral cat soft-catch leg-hold trapping

Feral cats devastate the Australian landscape and have been linked to a number of species extinctions through either predation or spread of diseases. Soft-catch leg-hold traps are routinely used to capture feral cats for research purposes or control, however by-catch is likely. Examination of by-catch data provided for six sites in Western Australia during the period 1997-2014 identified variability in by-catch across sites. This was attributed to differences in climate and landscape, the likely abundance of introduced predators prior to trapping and the experience of the trappers affecting when, where and how traps were set. Olfactory lures affected the taxonomy (with the exception of birds) of by-catch; reptiles were attracted to the PONGO lure (mix containing predator urine and faeces) used, but mammals were repelled. Reptiles may associate strong odours with food, while the mammals were cautious of the predatory species’ scent. Non-native by-catch were injured in traps less than the native by-catch most likely because they were generally better able to withstand the pressure from closing jaws. Amongst the native fauna; birds were more likely to be severely injured due to their morphology, behaviour and weight; amongst non-avian fauna species, the larger the captured individuals, the less likely they were to be injured due to their ability to better withstand the trap pressure. Injury to by-catch species poses animal ethics concerns, as approval to trap may be denied based on frequency and severity of injury to native and target species alike. It also raises concern for species of conservation significance that already have dwindling populations, such as the woylie, and can least afford the added threat from trapping. Future trapping exercises should proceed cautiously, with care taken in the timing of trapping, the placement of traps and the setting of traps (especially the treadle pressure needed to close the trap) to minimise the chance of by-catch and potential mortality. Additionally, by-catch welfare reports should be routinely prepared and examined to ensure best practice and on-going improvement