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Wild Animal Welfare
Our work on non-lethal wildlife management has focused largely on developing the use of learned food aversions for protecting target foods from wild mammals and birds. Such foods might be of conservation concern, e.g. the eggs of ground-nesting birds, or of agricultural or horticultural (and thus financial) value. As well as the obvious welfare advantage of not killing animals considered to be pests, non-lethal wildlife management may bring other practical benefits. For example, where a territorial animal is allowed to remain in situ, it prevents the invasion of conspecifics that can often follow the removal of a territory holder. The territory holder can instead be trained to avoid certain foods and in effect the 'poacher' becomes 'gamekeeper'. We conducted the first ever food aversion research with carrion crows (Corvus corone) and magpies (Pica pica) (Cox et al., 2004; Prescott et al., 1997). We conducted experiments to manipulate the food preferences of wild-caught birds in captivity, using Conditioned Taste Aversion (CTA), a particular kind of food aversion thought to have evolved among all taxa to allow animals to avoid poisoning. Birds are primarily visual animals and visual cues are therefore important in food selection. We successfully trained magpies to switch the colour of egg that they preferred to attack first; they subsequently showed colour-specific aversion to eggs and consumed less egg in total (Prescott et al., 1997). We developed our findings with magpies for the study on crows and trained them to delay their attack on a previously favoured egg colour even when this was subsequently untreated (Cox et al., 2004). We also established that crows did not generalize their aversion to eggs of a different colour, a potentially important consideration when designing realistic wildlife management strategies. These findings might be used to protect viable eggs of a particular target species from predation by wild corvids.
We have also demonstrated that learned food aversions may be used to protect target foods from mammals such as badgers and foxes. We set out to identify a practical non-lethal method of controlling wild mammal foraging, using European badgers (Meles meles) as models (badgers make excellent models for this work because they are opportunistic omnivores, widely reported as crop pests, and distributed across much of the northern hemisphere). This work was pioneering in that we conducted an iterative series of lab-style field experiments on wild animals in their natural environment, using video to record their detailed individual responses to variously treated target foods (Baker et al., 2005a, 2005b, 2007b, 2008). This was the first known CTA research conducted on badgers. In contrast to birds, mammals are olfactory animals and odours are important in their selection of food. First we established that badgers could be trained to avoid, at a distance (on the basis of odour), previously-favoured foods treated with an aversive agent (Baker et al., 2005b). Next we established that they could also learn to avoid untreated foods in the presence of an odour cue (Baker et al., 2007b). Then we conducted a dosage trial to establish the lowest effective dose on model crops (maize cobs) (Baker et al., 2005a), and finally we used this dose to demonstrate that badgers could be trained to avoid untreated maize cobs on the basis of an odour cue (Baker et al., 2008). We have also conducted related work on foxes using a process called Generalised Aversion in which an aversion is created using a bitter tasting substance called BitrexTM (Macdonald & Baker 2004). Generalised Aversion makes use of the fact that many animals have evolved to avoid potentially toxic alkaloids on the basis of bitterness. Our work has demonstrated learned food aversions could potentially provide a targeted, non-lethal approach for managing undesirable wildlife feeding behaviour.
We have recently completed a suite of studies on the humane management of moles. Until recently the most popular method of killing moles among farmers was strychnine poison. Strychnine kills by suffocation following paralysis of the respiratory muscles. Until recently, strychnine was uniquely available in Europe, and among species, for killing moles in the UK. In 2006 strychnine was withdrawn from use despite outcry from many users. We conducted a national survey of farmers, amenity managers and gardeners, to examine mole activity, damage and control in the UK following the strychnine ban. The survey also revealed that both the importance of humaneness in choosing a mole control method, and opinions regarding the humaneness of various mole control methods (including lethal and non-lethal methods), vary among stakeholder groups. Following on from the survey we conducted post-mortem research on the welfare impact of moles kill-trapped by land managers, as well as a study on the mechanical performance of mole (and rodent) traps and the potential welfare implications. We also conducted a pilot study on translocating moles as an alternative to culling (Shaw et al. in prep.). We are in the process of publishing the results of this work.
We are currently consolidating our research on humane wildlife management in an exciting new project on the quantitative assessment of the welfare impact of vertebrate pest management in the UK.
The other main strand to our current animal welfare portfolio is investigating the welfare impact of the wildlife trade.
Baker, S.E., Dutton, A., & Macdonald, D.W. (2006) The wildlife trade in East and Southeast Asia: an overview and analysis of the trade with specific reference to animal welfare. A report to the World Society for the Protection of Animals. The wildlife Conservation Research Unit, Zoology, University of Oxford.Baker, S.E., Ellwood, S.A., Slater, D., Watkins, R. and Macdonald, D.W. (2008). Learned food aversion plus odor cue protects crop from mammalian wildlife foraging. Journal of Wildlife Management, 72, 785-791.
Baker, S.E., Ellwood, S.A., Watkins, R.W. and Macdonald, D.W. (2005a). A dose-response trial with ziram-treated maize and free-ranging European Badgers Meles meles. Applied Animal Behaviour Science, 93, 309-321.
Baker, S.E., Ellwood, S.A., Watkins, R.W. and Macdonald, D.W. (2005b). Non-lethal control of wildlife: using chemical repellents as feeding deterrents for the European badger. Journal of Applied Ecology, 42, 921-931.
Baker, S.E., Johnson, P.J., Slater, D., R.W., W. and Macdonald, D.W. (2007b). Learned food aversion with and without an odour cue for protecting untreated baits from wild mammal foraging. In Conservation Enrichment and Animal Behaviour; Applied Animal Behaviour Science, special edition, R. Swaisgood, ed., pp. 410-428.
Baker, S.E. and Macdonald, D.W. (1999). Non-lethal predator control: exploring the options. In Advances in Vertebrate Pest Management, D.P. Cowan, and C.J. Feare, eds., Filander Verlag, Furth, pp. 251-266.
Baker, S.E., Singleton, G. and Smith, R.H. (2007a). The nature of the beast: using biological processes in vertebrate pest management. In Key Topics in Conservation Biology, D.W. Macdonald, and K. Service, eds., Blackwell Scientific, Oxford, pp. 173-185.
Cox, R., Baker, S., Macdonald, D.W. and Berdoy, M. (2004). Protecting egg prey from Carrion Crows: the potential of aversive conditioning. Applied Animal Behaviour Science, 87, 325-342.
Macdonald, D.W. and Baker, S.E. (2004). Non-lethal control of fox predation: the potential of generalised aversion. Animal Welfare, 13, 77-85.
Prescott, M.N., Berdoy, M. and Macdonald, D.W. (1997). Protecting egg prey from magpies (Pica pica): the potential of aversive conditioning. A report for the RSPB, WildCRU, Department of Zoology and Veterinary Services, University of Oxford, Bedfordshire, UK.