Background
Introduced predators can have a devastating effort on native species. Similarly introduced herbivores can have a devastating effort on native species by competing for the same resources e.g. food, rest sites and causing environmental damage. Traditional methods of controlling these introduced pests include shooting, baiting, trapping and fences. Another method are Judas animals (Campbell et al. 2005) that have been used to control vertebrate pests typically when most of the population has been removed. A Judas animal is a wild animal that is caught and fitted with a radio-tracking collar and then released back into its normal habitat where, if it is a gregarious species, it will go and find members of the same species. The radio-collar is used to find the Judas animal and then hunters kill the other animals it has found. The process is repeated where the Judas animal finds other animals until typically it stops finding congeners. This Judas animal is then killed, the collar removed and fitted onto a new wild caught animal and the process repeated. This is not a very efficient process as it relies on the Judas animal finding congeners, and inevitably they stop working (looking for congeners). This is a one way process where the Judas animal looks for congeners.
There is a very successful method of improving the efficiency of Judas animals by implanting hormones to extend oestrus in female animals such that they become extremely attractive to both male and females of the same species as the Judas animal (Campbell et al. 2007). Thus the ‘Mata Hari Judas’ animal looks for congeners because her reproductive ‘instinct’ is enhanced and congeners look for her because she is sexually attractive.
Aims
- Identify vertebrate pest species where traditional control methods are not 100% effective (e.g. cats, foxes, wild dogs, feral pigs)
- Under controlled conditions determine appropriate implant and dosage to induce prolonged oestrus of females of specific species
- Determine duration that Mata Hari Judas females are attractive to adult males of the same species
- Undertake field trials to determine effectiveness
Methodology
Adult females of the target species (e.g. goats, cats) are given a range of subcutaneous synthetic hormone implants (of different types and dosages) to determine firstly if the implant can induce oestrus and then to determine the duration of the induced oestrus.
Effectiveness of the implant is determined by exposing treated females, under controlled conditions, to adult males and monitoring both male and female behaviour. The greater the attractiveness of the female to the male and the longer that effect lasts then the better the implant. In the case of female goats it was possible to induce prolonged oestrus for over 100 days. Ensure welfare of the Mata Hari females are maintained.
Expected outcomes
A method to find and thus eradicate the small remnant population of vertebrate pests that typically evade being poisoned, shot or trapped during traditional control programs. A significant strength of the Mata Hari Judas technique is the eradication of lone male animals (as they are typically trap and hunter shy) that would otherwise escape a control program aimed at eradicating all animals in a pest population. Furthermore the Mata Hari Judas technique also has the advantage that it does not rely on the species targeted being gregarious.
References
Campbell, KJ, Baxter, GS, Murray, PJ, Coblentz, BE, and Donlan, CJ 2007, ‘Development of a prolonged estrus effect for use in Judas goats’. Applied Animal Behaviour Science, vol.102, pp.12-23.
Campbell, KJ, Baxter, GS, Murray, PJ, Coblentz, BE, Donlan, JD and Carrion, VG 2005, ‘Increasing the efficacy of Judas goats by sterilisation and pregnancy termination’. Wildlife Research, vol. 32, no. 8, pp. 737-43.
Cruz, F, Carrion, V, Campbell, KJ, Lavoie, C, and Donlan, CJ 2009, ‘Bio-Economics of Large-Scale Eradication of Feral Goats From Santiago Island, Galápagos’. Journal of Wildlife Management, vol. 73, no. 2, pp. 191-200.
Acknowledgements
Dr Karl Campbell was the UQ PhD student who developed the Mata Hari Judas goat technique on the Gatton campus and then used it to eradicate the remnant population of goats on Santiago Island, Galápagos (Cruz et al. 2009).
