Drought increases the impact of introduced European foxes on breeding Australian pelicans
Gregory R. Johnston
+ Author Affiliations
- Author Affiliations
A South Australian Museum, North Terrace, Adelaide, SA 5000, Australia.
B School of Biological Sciences, Flinders University of South Australia, GPO Box 2100, Adelaide, SA 5000, Australia.
C Discipline of Anatomy and Pathology, School of Medicine, University of Adelaide, SA 5005, Australia.
D Corresponding author. Email: pelecanus85@gmail.com
Wildlife Research 43(6) 507-514 https://doi.org/10.1071/WR15207
Submitted: 4 November 2015 Accepted: 22 August 2016 Published: 26 October 2016
Abstract
Context: Introduced mammalian predators have been responsible for population declines in native prey species around the world. Many conservation programs rely on control or eradication of introduced mammalian predators, but the impact of environmental variation on the efficacy of this approach is rarely documented.
Aims: The present paper describes (1) the impact of introduced European foxes (Vulpes vulpes) on breeding Australian pelicans (Pelecanus conspicillatus) in South Australia and (2) the responses of both species to a fox-eradication program using a before-after-impact framework.
Methods: The impact of foxes on breeding Australian pelicans was studied on a near-shore island. An index of fox abundance and direct measurements of breeding pelicans and mortality of pelican eggs and young were compared before foxes were established on the island, while foxes were resident and during a fox-eradication program. A path analysis was used to explore the causal relationships between fox abundance and other potential covariates (e.g. rainfall) on breeding pelicans.
Key results: Before foxes were established on the island, the number of breeding pelicans grew and egg mortality was low. While foxes were resident, the number of breeding pelicans fell and egg mortality rose. This was followed by an increase in the number of breeding pelicans and a decrease in egg mortality during a fox-eradication program. While foxes had a clear impact on egg mortality, a period of low rainfall also occurred while foxes were resident. The path analysis showed an interaction among rainfall, size of the pelican breeding population and the impact of foxes. In drought years, fewer pelicans bred and foxes were a major cause of nest abandonment when they entered pelican breeding colonies to prey on eggs.
Conclusions: These results confirmed that foxes can be an important predator of ground-nesting, colonial waterbirds, and showed that the impact of foxes may be higher in drought years when prey populations are low.
Implications: The present study suggests that an increase in the incidence of droughts as a result of climate change may increase the impact of introduced predators on drought-sensitive waterbirds and raises the possibility of focussing predator-control efforts during droughts, as periods of particular risk to colony-breeding waterbirds.
Additional keywords: climate change, conservation outcome, evidence-based conservation, fox baiting, introduced predator, management effectiveness, predation.
References
Anderson, D. W., Keith, J. O., Trapp, G. R., Gress, F., and Moreno, L. A. (1989). Introduced small ground predators in California brown pelican colonies. Colonial Waterbirds 12, 98–103.| Introduced small ground predators in California brown pelican colonies.Crossref | GoogleScholarGoogle Scholar |
Arbuckle, J. L. (2013) ‘IBM SPSS Amos 22 User’s Guide.’ (IBM Corporation: Chicago, IL.)
Barter, M., Newsome, D., and Calver, M. C. (2008). Preliminary quantitative data on behavioural responses of Australian pelicans (Pelecanus conspicillatus) to human approach on Penguin Island, Western Australia. Journal of Ecotourism 7, 197–212.
| Preliminary quantitative data on behavioural responses of Australian pelicans (Pelecanus conspicillatus) to human approach on Penguin Island, Western Australia.Crossref | GoogleScholarGoogle Scholar |
Beale, C. M., and Monaghan, P. (2004). Human disturbance: people as predation-free predators? Journal of Applied Ecology 41, 335–343.
| Human disturbance: people as predation-free predators?Crossref | GoogleScholarGoogle Scholar |
Blackburn, T. M., Cassey, P., Duncan, R. P., Evans, K. L., and Gaston, K. J. (2004). Avian extinction and mammalian introductions on oceanic islands. Science 305, 1955–1958.
| Avian extinction and mammalian introductions on oceanic islands.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2cXnslSlsr0%3D&md5=07445c30b27e92e544a79cfab7a61109CAS | 15448269PubMed |
Blokpoel, H. (1971). Fox predation on a bird island. Blue Jay 29, 32–33.
Brown, L. H., and Urban, E. K. (1969). The breeding biology of the great white pelican Pelecanus onocrotalus roseus at Lake Shala, Ethiopia. The Ibis 111, 199–237.
| The breeding biology of the great white pelican Pelecanus onocrotalus roseus at Lake Shala, Ethiopia.Crossref | GoogleScholarGoogle Scholar |
Bunnell, F. L., Dunbar, D., Koza, L., and Ryder, G. (1981). Effects of disturbance on the productivity and numbers of white pelicans in British Columbia: observations and models. Colonial Waterbirds 4, 2–11.
| Effects of disturbance on the productivity and numbers of white pelicans in British Columbia: observations and models.Crossref | GoogleScholarGoogle Scholar |
Catsadorakis, G., Malakou, M., and Crivelli, A. J. (1996). The effects of the 1989/1990 drought on the colonial waterbirds nesting at Lake Mikri Prespa, Greece, with special emphasis on Pelicans. Colonial Waterbirds 19, 207–218.
| The effects of the 1989/1990 drought on the colonial waterbirds nesting at Lake Mikri Prespa, Greece, with special emphasis on Pelicans.Crossref | GoogleScholarGoogle Scholar |
Cote, I. M., and Sutherland, W. J. (1997). The effectivenness of removing predators to protect bird populations. Conservation Biology 11, 395–405.
| The effectivenness of removing predators to protect bird populations.Crossref | GoogleScholarGoogle Scholar |
Courchamp, F., Chapuis, J. L., and Pascal, M. (2003). Mammal invaders on islands: impact, control and control impact. Biological Reviews of the Cambridge Philosophical Society 78, 347–383.
| Mammal invaders on islands: impact, control and control impact.Crossref | GoogleScholarGoogle Scholar | 14558589PubMed |
Crawford, R. J. M., Cooper, J., and Dyer, B. M. (1995). Conservation of an increasing population of great white pelicans Pelecanus onocrotalus in South Africa’s western cape. South African Journal of Marine Science 15, 33–42.
| Conservation of an increasing population of great white pelicans Pelecanus onocrotalus in South Africa’s western cape.Crossref | GoogleScholarGoogle Scholar |
Crivelli, A. J., and Schreiber, R. W. (1984). Status of the pelecanidae. Biological Conservation 30, 147–156.
| Status of the pelecanidae.Crossref | GoogleScholarGoogle Scholar |
Crivelli, A., and Vizi, O. (1981). The dalmatian pelican, Pelecanus crispus Bruch 1832, a recently world-endangered bird species. Biological Conservation 20, 297–310.
| The dalmatian pelican, Pelecanus crispus Bruch 1832, a recently world-endangered bird species.Crossref | GoogleScholarGoogle Scholar |
Croll, D. A., Maron, J. L., Estes, J. A., Danner, E. M., and Byrd, G. (2005). Introduced predators transform subarctic islands from grassland to tundra. Science 307, 1959–1961.
| Introduced predators transform subarctic islands from grassland to tundra.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXisVyiurw%3D&md5=f86752cd4d06b0d95b39d124c111f873CAS | 15790855PubMed |
Fisher, D. O., Johnson, C. N., Lawes, M. J., Fritz, S. A., McCallum, H., Blomberg, S. P., VanDerWal, J., Abbott, B., Frank, A., Legge, S., Letnic, M., Thomas, C. R., Fisher, A., Gordon, I. J., and Kutt, A. (2014). The current decline of tropical marsupials in Australia: is history repeating? Global Ecology and Biogeography 23, 181–190.
| The current decline of tropical marsupials in Australia: is history repeating?Crossref | GoogleScholarGoogle Scholar |
Groombridge, B. (Ed.) (1992). ‘Global Biodiversity: Status of the Earth’s Living Resources.’ (Chapman and Hall: London.)
Hansen, B. D., Menkhorst, P., Moloney, P., and Loyn, R. H. (2015). Long-term declines in multiple waterbird species in a tidal embayment, south-east Australia. Austral Ecology 40, 515–527.
| Long-term declines in multiple waterbird species in a tidal embayment, south-east Australia.Crossref | GoogleScholarGoogle Scholar |
Holm, G. O., Heiss, T. J., Justic, D., McNease, L., Linscombe, R. G., and Nesbitt, A. S. (2003). Population recovery of the eastern brown pelican following its extirpation in Louisiana. The Wilson Bulletin 115, 431–437.
| Population recovery of the eastern brown pelican following its extirpation in Louisiana.Crossref | GoogleScholarGoogle Scholar |
Hughes, L. (2003). Climate change and Australia: trends, projections and impacts. Austral Ecology 28, 423–443.
| Climate change and Australia: trends, projections and impacts.Crossref | GoogleScholarGoogle Scholar |
Johnston, G. R. (2016). Breeding biology of Australian pelicans on the coast of southern Australia. Waterbirds 39, 300–305.
Johnston, G. R. (2017). Methods for field recognition of individual Australian pelicans (Pelecanus conspicillatus) from laying to adulthood. Corella 41, 1–7.
Johnston, G. R., and Harbison, P. (2005). The Barker Inlet–Port River estuary. In ‘Adelaide, Nature of a City’. (Eds C. B. Daniels and C. J. Tait.) pp. 287–313. (BioCity, Centre for Urban Habitats: Adelaide.)
Johnston, G. R., and Wiebkin, A. (2008). Birds of Gulf St Vincent. In ‘Natural History of Gulf St Vincent’. (Eds S. Shepherd, P. Harbison and S. Bryars.) pp. 324–338. (Royal Society of South Australia: Adelaide.)
Johnston, G. R., Waterman, M. H., and Manning, C. E. (2015). Movement and mortality of Australian pelicans (Pelecanus conspicillatus) banded at inland and coastal breeding sites in South Australia. Pacific Conservation Biology 21, 271–276.
| Movement and mortality of Australian pelicans (Pelecanus conspicillatus) banded at inland and coastal breeding sites in South Australia.Crossref | GoogleScholarGoogle Scholar |
Kirkwood, R., Sutherland, D. R., Murphy, S., and Dann, P. (2014). Lessons from long-term predator control: a case study with the red fox. Wildlife Research 41, 222–232.
| Lessons from long-term predator control: a case study with the red fox.Crossref | GoogleScholarGoogle Scholar |
Krajick, K. (2005). Winning the war against island invaders. Science 310, 1410–1413.
| Winning the war against island invaders.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXht1yqsLzL&md5=5c972c07db8f040b0343e59e53175ea8CAS | 16322433PubMed |
Lavers, J., Wilcox, C., and Donlan, C. J. (2010). Bird demographic responses to predator removal programs. Biological Invasions 12, 3839–3859.
| Bird demographic responses to predator removal programs.Crossref | GoogleScholarGoogle Scholar |
Madden, E. M., and Restani, M. (2005). History and breeding ecology of the American white pelican at Medicine Lake National Wildlife Refuge, Montana. Waterbirds 28, 23–26.
| History and breeding ecology of the American white pelican at Medicine Lake National Wildlife Refuge, Montana.Crossref | GoogleScholarGoogle Scholar |
Maguire, G. S., Stojanovic, D., and Weston, M. A. (2009). Conditioned taste aversion reduces fox depredation on model eggs on beaches. Wildlife Research 36, 702–708.
| Conditioned taste aversion reduces fox depredation on model eggs on beaches.Crossref | GoogleScholarGoogle Scholar |
Martin, T. E. (1993). Nest predation among vegetation layers and habitat types: revising the dogmas. American Naturalist 141, 897–913.
| Nest predation among vegetation layers and habitat types: revising the dogmas.Crossref | GoogleScholarGoogle Scholar | 1:STN:280:DC%2BD1Mzjt1Gksg%3D%3D&md5=587ee62417b8591e32cbd72b529f5281CAS | 19425994PubMed |
Moseby, K. E., Hill, B. M., and Read, J. (2009). Arid recovery: a comparison of reptile and small mammal populations inside and outside a large rabbit, cat and fox-proof exclosure in arid South Australia. Austral Ecology 34, 156–169.
| Arid recovery: a comparison of reptile and small mammal populations inside and outside a large rabbit, cat and fox-proof exclosure in arid South Australia.Crossref | GoogleScholarGoogle Scholar |
Nisbet, I. C. T. (2000). Disturbance, habituation, and management of waterbird colonies. Waterbirds 23, 312–332.
| Disturbance, habituation, and management of waterbird colonies.Crossref | GoogleScholarGoogle Scholar |
O’Brien, M. B., Corrick, A. H., and Lacey, G. (2010). Breeding sites of the Australian pelican, Pelecanus conspicillatus in Victoria. Australian Field Ornithology 27, 19–30.
O’Connor, R. J. (1991). Long-tern population studies in the US. The Ibis 1, 30–48.
Paton, D. C., Rogers, D. J., Hill, B. M., Bailey, C. P., and Ziembicki, M. (2009). Temporal changes to spatially stratified waterbird communities of the Coorong, South Australia: implications for the management of heterogenous wetlands. Animal Conservation 12, 408–417.
| Temporal changes to spatially stratified waterbird communities of the Coorong, South Australia: implications for the management of heterogenous wetlands.Crossref | GoogleScholarGoogle Scholar |
Paullin, D. G., Ivey, G. L., and Littlefield, C. D. (1988). The re-establishment of American white pelican nesting in the Malheur–Harney Lakes Basin, Oregon. The Murrelet 69, 61–64.
| The re-establishment of American white pelican nesting in the Malheur–Harney Lakes Basin, Oregon.Crossref | GoogleScholarGoogle Scholar |
Peja, N., Sarigul, G., Siki, M., and Crivelli, A. J. (1996). The Dalmatian pelican, Pelecanus crispus, nesting in Mediterranean lagoons in Albania and Turkey. Colonial Waterbirds 19, 184–189.
| The Dalmatian pelican, Pelecanus crispus, nesting in Mediterranean lagoons in Albania and Turkey.Crossref | GoogleScholarGoogle Scholar |
Porter, J. L., Kingsford, R. T., and Hunter, S. J. (2006). Aerial surveys of wetland birds in eastern Australia, October 2003–2005. Department of Environment & Conservation, Sydney, New South Wales.
Reid, J. (2009). Australian pelican: flexible responses to uncertainty. In ‘Boom and Bust: Bird Stories for a Dry Country’. (Eds L. Robin, R. Heinsohn and L. Joseph.) pp. 95–120. (CSIRO Publishing: Melbourne.)
Robinson, O. J., and Dindo, J. J. (2011). Egg success, hatching success, and nest-site selection of brown pelicans, Gaillard Island, Alabama, USA. The Wilson Journal of Ornithology 123, 386–390.
| Egg success, hatching success, and nest-site selection of brown pelicans, Gaillard Island, Alabama, USA.Crossref | GoogleScholarGoogle Scholar |
Salo, P., Korpimäki, E., Banks, P. B., Nordström, M., and Dickman, C. R. (2007). Alien predators are more dangerous than native predators to prey populations. Proceedings of the Royal Society of London. Series B, Biological Sciences 274, 1237–1243.
| Alien predators are more dangerous than native predators to prey populations.Crossref | GoogleScholarGoogle Scholar |
Saunders, G. R., Gentle, M. N., and Dickman, C. R. (2010). The impacts and management of foxes Vulpes vulpes in Australia. Mammal Review 40, 181–211.
| The impacts and management of foxes Vulpes vulpes in Australia.Crossref | GoogleScholarGoogle Scholar |
Schreiber, R. W., and Risebrough, R. W. (1972). Studies of the brown pelican 1. Status of brown pelican populations in the United States. The Wilson Bulletin 84, 119.
Seaman, G. A., and Randall, J. E. (1962). The mongoose as a predator in the Virgin Islands. Journal of Mammalogy 43, 544–546.
| The mongoose as a predator in the Virgin Islands.Crossref | GoogleScholarGoogle Scholar |
Smith, R. K., Pullin, A. S., Stewart, G. B., and Sutherland, W. J. (2010). Effectiveness of predator removal for enhancing bird populations. Conservation Biology 24, 820–829.
| Effectiveness of predator removal for enhancing bird populations.Crossref | GoogleScholarGoogle Scholar | 20067492PubMed |
Sovada, M. A., King, D. T., Erickson, M., and Gray, C. (2005). Historic and current status of the American white pelican breeding at Chase Lake National Wildlife Refuge, North Dakota. Waterbirds 28, 27–34.
| Historic and current status of the American white pelican breeding at Chase Lake National Wildlife Refuge, North Dakota.Crossref | GoogleScholarGoogle Scholar |
Troup, G., and Dutka, T. L. (2014). Osmotic concentration of prey affects food discrimination behaviour in the Australian pelican. Journal of Zoology 294, 170–179.
| Osmotic concentration of prey affects food discrimination behaviour in the Australian pelican.Crossref | GoogleScholarGoogle Scholar |
Vestjens, W. J. M. (1977). Breeding behaviour and ecology of the Australian pelican, Pelecanus conspicillatus, in New South Wales. Australian Wildlife Research 4, 37–58.
| Breeding behaviour and ecology of the Australian pelican, Pelecanus conspicillatus, in New South Wales.Crossref | GoogleScholarGoogle Scholar |
Vincent, D. J. (1988). Nesting of the kelp gull and other new breeding records from Outer Harbour. South Australian Ornithologist 30, 122–124.
Walsh, J. C., Wilson, K. A., Benshemesh, J., and Possingham, H. P. (2012). Unexpected outcomes of invasive predator control: the importance of evaluating conservation management actions. Animal Conservation 15, 319–328.
| Unexpected outcomes of invasive predator control: the importance of evaluating conservation management actions.Crossref | GoogleScholarGoogle Scholar |
