The pest status of Australian white ibis (Threskiornis molucca) in urban situations and the effectiveness of egg-oil in reproductive control
John M. Martin A C , Kris French A and Richard E. Major BA Institute for Conservation Biology, School of Biological Sciences, University of Wollongong, Wollongong, NSW 2522, Australia.
B Australian Museum, 6 College Street, Sydney, NSW 2010, Australia.
C Corresponding author. Email: john.martin@cp.nsw.gov.au
Wildlife Research 34(4) 319-324 https://doi.org/10.1071/WR07005
Submitted: 8 January 2007 Accepted: 30 May 2007 Published: 28 June 2007
Abstract
The Australian white ibis (Threskiornis molucca) is considered to be an urban pest along the east coast of Australia. The non-specific diet and broad habitat requirements of ibis have facilitated their successful exploitation of the urban environment. Ibis are considered a pest because they pose a threat to aircraft safety, scavenge food at waste-management sites, cafés and parks, and compete with other native species for food and habitat. This study assesses a new ibis-management technique, the application of ‘egg-oil’ to suppress hatching. On other species, egg-oiling has been shown to be environmentally safe and socially preferable to culling adult birds. Approximately 5 mL of food-grade canola oil was sprayed upon each egg, and both incubator and field trials were used to investigate the efficacy of this technique on ibis and to determine the optimal application time and frequency of egg-oil. Treatment eggs were given an application of oil during the 23-day incubation period either once per week, or once early (<7 days), mid (~14 days) or late (>18 days) incubation. All four treatments were observed to be 100% effective at preventing ibis eggs from hatching during the laboratory trial and more than 98% effective during the field trial. These results indicate that applying canola oil to ibis eggs once, at any time, during the 23-day incubation period is sufficient to prevent ibis eggs from hatching. The field trial also showed that 30% of ibis, across the four oiling treatments, continued to incubate the unviable eggs for up to 54 days longer than the normal incubation period. Given that ibis are multibrooded, raising up to three successful clutches in a breeding season, the increased time devoted to incubating oil-treated eggs could reduce the opportunity for multiple broods, compared with conventional egg destruction. The egg-oil technique offers an additional tool for land managers to conduct ibis reproduction control, which should reduce the amount of time required to conduct ibis management, consequently reducing the cost to land managers.
Acknowledgements
Funding for this project came from Fairfield City Council, Waste Services New South Wales, the Centennial Parklands Foundation and the Australian Museum’s Postgraduate Awards. We specifically thank Katie Cabezas of Fairfield City Council, Joan Dawes of Pestat and Geoff Ross of the New South Wales Department of Environment and Conservation (NSW DEC). Thank you also to the two anonymous reviewers. This research was undertaken in accordance with the requirements of the University of Wollongong Animal Ethics Committee and with approval from the NSW DEC (NPWS).
Blackwell, F. B. , Seamans, T. W. , Helon, D. A. , and Dolbeer, R. A. (2000). Early loss of herring gull clutches after egg-oiling. Wildlife Society Bulletin 28, 70–75.
Kingsford, R. T. , and Johnson, W. (1998). Impact of water diversions on colonially-nesting waterbirds in the Macquarie marshes of arid Australia. Colonial Waterbirds 21, 159–170.
| Crossref | GoogleScholarGoogle Scholar |
Kopij, G. (1999). Breeding ecology of the sacred ibis Threskiornis aethiopicus in the Free State, South Africa. South African Journal of Wildlife Research 29, 25–30.
Le Souëf, W. H. D. (1917). Australian ibises. Emu 17, 94–95.
Lowe, K. W. , and Richards, G. C. (1991). Morphological variation in the sacred ibis Threskiornis aethiopicus superspecies complex. Emu 91, 41–45.
Mayfield, H. F. (1975). Suggestions for calculating nest success. Wilson Bulletin 87, 456–466.
Underwood, M. , and Bunce, A. (2004). The breeding biology of the white-faced storm petrel (Pelagodroma marina) on Mud Island, Port Phillip Bay, Victoria. Emu 104, 213–220.
| Crossref | GoogleScholarGoogle Scholar |
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