Predator faecal odours as repellents to manage feral goats and kangaroos
Predator odours have been evaluated as repellents for vertebrate pests including faeces, urine, anal scent gland contents and hair, with research over the last 30 years showing that predator odours can vary in their success. What the body of research highlights, however, is that very little is actua...
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| Format: | Thesis |
| Language: | unknown |
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The University of Queensland, School of Animal Studies
2010
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| Online Access: | https://espace.library.uq.edu.au/view/UQ:220703/s33527617_PhD_abstract.pdf https://espace.library.uq.edu.au/view/UQ:220703/s33527617_PhD_totalthesis.pdf https://espace.library.uq.edu.au/view/UQ:220703 |
| Summary: | Predator odours have been evaluated as repellents for vertebrate pests including faeces, urine, anal scent gland contents and hair, with research over the last 30 years showing that predator odours can vary in their success. What the body of research highlights, however, is that very little is actually known about the effective use of predator odours as repellents. Some unanswered themes throughout this research are: 1) whether a sympatric or allopatric predator odour is more successful and 2) whether the diet of the predator can affect its faecal odour and therefore its success as a repellent. To date the first of these themes has not been rigorously tested. The effect of predator diet has only been evaluated in a small number of studies, with the majority evaluating the difference between meat and vegetable diets rather than the difference between diets consisting of the target species conspecifics and heterospecifics. Furthermore, these effects have not been evaluated on Australian native vertebrate pest species. The hypothesis for this thesis was that predator faecal odours were effective repellents against Australian pests. In this study, the faecal odours of metatherian (Tasmanian devil, Sarcophilus harrisi) and eutherian (Sumatran tiger, Panthera tigris sumatrae) predators were evaluated against two vertebrate pest species in Australia; one metatherian (eastern grey kangaroo, Macropus giganteus) and one eutherian (goat, Capra hircus). The predators were fed two diets: one consisting of goat and the other of eastern grey kangaroo carcases. The resultant faecal odours of each of these diets (tiger fed goat = tiger:goat, tiger fed kangaroo = tiger:roo, Tasmanian devil fed goat = devil:goat, Tasmanian devil fed kangaroo = devil:roo) were evaluated for their success as repellents against both goats and eastern grey kangaroos. Based on feed residue data from pen trials, test faecal odours deterred goats from feed (P > 0.001) and tiger faecal odours were more successful than Tasmanian devil faecal odours (P = 0.03). There was no difference between the two types of tiger faecal odours in their repellence (P = 0.68). Tiger faecal odours were more successful than Tasmanian devil faecal odours at deterring kangaroos from supplementary feed (P = 0.02), with no significant difference between tiger:goat and tiger:roo faecal odours (P = 0.26). Feeding events by goats were observed less often at a trough containing tiger:goat faecal odour than at all other test odour troughs (χ42, α = 0.01, P < 0.001). A similar pattern was seen for kangaroos with feeding events observed least often at the trough containing tiger:roo faecal odour. To further evaluate the effect of eutherian odours, faecal odours from two other eutherian predatory species (African lion, P. leo and dingo, Canis lupus familiaris) were tested, with tiger faecal odour, under field conditions. Only tiger faecal odour was successful at modifying goat grazing patterns with goats moving away from where the test odour was placed for each day of the testing period (P = 0.01). Both tiger (P = 0.03) and lion (P = 0.03) faecal odour resulted in goats moving their resting locations away from the test odour. In the first kangaroo field trial feed residue was affected by repellent (P = 0.04) with more supplementary feed consumed at the control feed trough (P = 0.04) than at any other feed trough. All predator faecal odours reduced feed residue (lion, P = 0.01; tiger, P = 0.02; dingo, P = 0.04) with faecal odour from the African lion having the greatest level of significance. During the second field trial, more supplementary feed was consumed by kangaroos at the control odour feed station than at any other feed station (P < 0.001). There was no difference in supplementary feed intake by kangaroos at feed troughs with all predator faecal odours deterring kangaroos from supplementary feed. Chemical analysis by HS-SPME-GCMS of the volatile compounds from the faecal samples revealed differences in the chemical profile between species and between diets within species, however, there was no significant difference in the number of compounds between predators, or between diets. Habituation to tiger and Tasmanian devil faecal odours by both target species was observed in the paddock trials. In contrast, no habituation by kangaroos and goats to tiger, lion (and for kangaroos, dingo) faecal odours occurred during field trials. These results suggest that while paddock trials indicate which odour may be successful in the field, paddock trials should be considered an artificial environment and may not accurately reflect what will be observed in the field. In conclusion, eutherian predator faecal odours are successful feeding deterrents for goat and kangaroo pests in Australia. Repellent success was not affected by previous sympatric or allopatric relationships between the predator and the target pest species. |
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