Systems for the environmentally safe and humane control of Indian Mynas
A project undertaken at the School of Resources, Environment and Society, Australian National University, Canberra, and supervised by Chris TidemannThis project is aimed at developing systems for reducing populations of Indian Mynas in a safe and humane fashion. The Myna is already a significant pest in Australia and one that is likely to continue to increase in importance. The present range of Mynas is eastern Queensland, NSW, Victoria and the ACT, although not (yet) in Tasmania, South Australia, Western Australia or the Northern Territory. There is little doubt that Mynas are capable of expanding well beyond their present range because of their broad climatic and habitat tolerances and their extreme adaptability. Mynas are strongly commensal ie, attracted to human habitation (with attendant food supply) - but they are perfectly capable of existing without humans. The highest densities of Mynas in Australia have been recorded in tropical cities (eg, Cairns 1,000 birds per km2), but they are far from being just urban birds, becoming increasingly common in the modified woodlands that dominate much of Australia (Barson et al 2000).
Mynas are known to disrupt breeding of some native Australian birds, especially hollow-nesting species (Pell and Tidemann 1997a,b) and, because of their disruptive effect on native wildlife, were recently listed by the World Conservation Union as among the World’s 100 Worst Invasive Species (Lowe et al. 2000). So far, the ranges of most threatened species in Australia have not been invaded by Mynas, but given the clear trend toward range expansion, it is probable that this will occur in the near future. Recently, Mynas have begun to invade the breeding range of the hollow-nesting (and Vulnerable) Superb Parrot in NSW to the north of the ACT (Murrumbateman, Yass) and individuals have found their way to Perth and northern Tasmania. Over the past few years, Mynas have come to be recognized and strongly disliked by a growing part of the Australian community. Mynas were recently ranked by respondents to the ABC’s Wildwatch Survey as the “Most Significant Pest” in Australia (Australian Broadcasting Corporation 2004). There is also concern, especially where Mynas are at high densities, of risk to human and livestock health from fouling. The propensity of Mynas to steal food from domestic animals and from humans at outdoor eating areas means that there is a high likelihood of pathogen transmission if infective birds, livestock, or people come into contact (Tidemann 2005).
Funding from the Hermon Slade Foundation has enabled research to be initiated into developing systems for catching mynas at communal roosts, where there is potential to catch and remove very large numbers of birds at once. Traps to catch Mynas selectively and humanely in feeding areas are already commercially available, but on their own it is unlikely that these traps are capable of generating an overall reduction in the Myna population. Accordingly, research is now targetting communal roosts. Three parallel lines of enquiry are being followed: (1) an investigation into the characteristics of structures (trees and buildings) used by wild birds as roosting sites what makes an ideal Myna roost? (2) aviary trials with captive Mynas to experimentally test for preferences in roost sites and (3) analysis of Myna flocking calls and call-playback trials to move roosting flocks from one site to another. Like other flocking species, such as sheep and flying-foxes, it is possible to move flocks cohesively over short distances with sound (Tidemann 2003). The ultimate objective of this research is to develop a mobile, sup-attractive, synthetic roost that can be used, in combination with call playback, to attract and trap roosting flocks of mynas. Research so far has been concentrated in Canberra. Additional funding from the NSW Department of Environment and Conservation and the Commonwealth Department of Environment and Heritage will enable parallel investigations to be made in Sydney and Cairns, so spanning a large part of the Myna’s climatic range.
Australian Broadcasting Corporation (2004) http://www.abc.net.au/wildwatch/results/award.htm
Barson, M., L. Randall and V. Bordas (2000). Land cover changes in Australia. Bureau of Rural Sciences, Canberra.
Lowe, S., M. Browne, M. Boudjelas and M. De Poorter (2000). 100 of the World's Worst Invasive Alien Species. Invasive Species Specialist Group (International Union for the Conservation of Nature), Auckland. www.issg.org/booklet.pdf
Pell, A. S. and C. R. Tidemann (1997a). The ecology of the common myna (Acridotheres tristis) in urban nature reserves in the Australian Capital Territory. Emu 97: 141-149.
Pell, A. S. and C. R. Tidemann (1997b). The impact of two exotic hollow-nesting birds on two native parrots in savannah and woodland in eastern Australia. Biological Conservation 79: 145-153.
Tidemann, C. R. (2003). Displacement of a flying-fox camp using sound. Ecological Management and Restoration 4: 224-226.
Tidemann, C. (2005). Indian Mynas - Can the problems be controlled? Pps. 55-58 in Proceedings of the 15th National Urban Animal Management Conference, Canberra, (Ed. M. Hayward) Australian Veterinary Association, Artarmon.
Tidemann, C. (2006) The Indian Myna. http://sres.anu.edu.au/associated/myna/index.html
Fig. 1. The Indian Myna was brought to Australia from India in the 1860s - originally to control insect pests in market gardens. The Myna is now a major pest in eastern Australia and many other parts of the world. Picture by Andrew Tatnell, Big Island Photographics.
Fig. 2. Mynas nest in hollows, often aggressively displacing native wildlife - hence their negative impact on biodiversity. Mynas also steal food from livestock and humans at outdoor eating areas, thereby generating risk to human and livestock health. Picture by Andrew Tatnell, Big Island Photographics.
Fig. 3. Mynas can be trapped safely, selectively and humanely with these Myna Magnet traps that were developed at the ANU, but these traps are unlikely to be able to generate a reduction in the Myna population overall. Research is now focussed on developing systems for trapping Mynas at communal roosts. Pic by Chris Tidemann.
Fig. 4. Mynas are highly social birds that roost together in large groups, often returning to the same place each night. These gatherings are termed communal roosts. Pic by Andrew Tatnell, Big Island Photographics.
Fig. 5. A Myna roost site in a group of five Pencil Pines. Several hundred Mynas have roosted here, on and off, for at least five years. Pic by Chris Tidemann.
Fig. 6. The roof supports of this disused building are occupied each night by around five hundred roosting Mynas. The objective of this research is to develop systems for trapping Mynas at these communal roost sites. Pic by Chris Tidemann.
Fig. 7. Roost preferences of Mynas are being tested in this large, outdoor aviary 30 x 5 x 5 m, which houses a flock of 100 birds. Different roosting conditions are made available to the captive birds in the turrets at each end of the aviary. Roosting behaviour is monitored via closed-circuit television and infra-red cameras. Pic by Toby Roscoe.
Fig. 8. Roosting behaviour of Mynas in the aviary is monitored by infra-red cameras and closed-circuit television. Pic by Toby Roscoe.
Fig. 9. Media coverage of the project was used to elicit public information about myna roosts in Cairns. Photo by Toby Roscoe.
Fig. 10. The eye of tropical Cyclone Larry passed to the south of Cairns in March 2006, leaving behind many damaged trees in its wake. “Damaged mynas? We didn’t find any - apart from a few moving to a new roost the mynas seemed to carry on as if nothing had happened.? Photo by Toby Roscoe.
Fig. 11. Flying myna - the distinctive white wing-patches are clearly visible. Photo by Toby Roscoe
Fig. 12. The new myna trap is supported by 15m yacht masts mounted on trailers, stabilised with ballast tanks and extendable feet. One trailer rides piggyback atop the other for transport between trapping sites. The two masts are positioned either side of a roost tree, and provide a platform from which a very large net can be remotely lowered to enclose the occupants. Photo : C. R. Tidemann.