SEARCH

SEARCH BY CITATION

Keywords:

  • deterrent;
  • environmental management;
  • mining;
  • waterfowl mortality

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

1. A deterrent was used in conjunction with engineering and management techniques to discourage nomadic waterfowl from landing and remaining on toxic waterbodies.

2. Four behavioural traits of nomadic waterfowl were exploited in the development of the deterrent: nocturnal movements, attraction to reflective surfaces, fear of diurnal predators, and naivety to local conditions and deterrents.

3. A rotating, intermittent beacon directed at a shallow angle across the water surface effectively discouraged most waterfowl. This beacon was floating and solar-powered and built to be acid resistant.

4. A series of deterrents, with gas-powered sonic guns and provision of clean alternative waterbodies nearby, significantly lessened the likelihood of waterfowl injury or mortality on toxic waterbodies.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

Many waterbird species are highly nomadic, flying long distances to take advantage of suitable conditions in temporary waterbodies (Norman 1979; Briggs 1992; Kingsford & Porter 1993; Lawler et al. 1993). Artificial waters, such as dams, sewage ponds, boredrains and mining waterbodies, are used extensively by waterfowl in arid Australia, presumably as refugia during long-distance movements (Braithwaite & Stewart 1975; Badman 1987). Many waterfowl migrate at night and sometimes alight on unsuitable or even hazardous shiny surfaces, such as iron roofs, wet tarmac or toxic ponds (P. Langdon, personal communication; J.L. Read, personal observation). A compounding problem could be the selection of inappropriate landing sites by hungry, thirsty or exhausted birds searching for food, water or resting sites. While waterfowl injury or death occurs naturally as a result of birds failing to reach suitable waters, interactions with the anthropogenic landscape have in some cases also resulted in the mortality of nomadic waterfowl.

Poisoning of waterfowl that use toxic tailings dams, which store waste products from mineral extraction, is widespread in Australia (Ryan & Shanks 1996), although published information is not widely available. In a typical year, approximately 1000 birds die in Australian gold mine tailings dams, with less than five deaths per annum at most individual dams (Minerals Council of Australia 1996). However, irregular incidents occasionally result in more than 100 deaths, including 2700 waterbirds at Northparkes (NSW) in 1995 and 60 000 budgerigars at Mt. Windarra (WA) in 1985 (Minerals Council of Australia 1996). Cyanide was probably the cause of these bird deaths (Minerals Council of Australia 1996; Ryan & Shanks 1996).

Changes to toxic liquid management and the reduction in the size or toxicity of the dams have sometimes effectively alleviated the risk of mass waterfowl mortality, although such measures are not always logistically or economically viable. Alternatively various attempts have been made to discourage birds from using tailings dams, but these are seldom systematic or published. Covering ponds or floating a dense bed of plastic, hollow balls on the surface (MEM 1996a) are also not feasible for large areas, or where high evaporation rates are desirable. Floats or streamers may limit the number of large diurnally flying birds, such as black swans Cygnus atratus, from landing on dams (Minerals Council of Australia 1996). The success of pyrotechnic launchers and sound systems are effective in some cases (MEM 1996b) but not others (Stickley, Mott & King 1995), when waterfowl compensate for anthropocentric disturbance through habituation or behaviour alteration (Draulans & van Vessem 1985; Davidson & Rothwell 1993; Ward & Andrews 1993; Fox & Madsen 1997).

Several clean and toxic waterbodies are associated with the Olympic Dam mine site and nearby town of Roxby Downs in arid South Australia (Fig. 1). Over 50 waterbird species have been recorded from within 50 km of Olympic Dam (Read 1994) and the population of waterfowl in this region can approach 150 000 birds following flooding rains (Read & Ebdon 1998). Most waterbirds use either natural lakes, the fresh water storage ponds at the Desalination Plant or the nearby Roxby Downs sewage ponds (ODC 1996). Bird use of the toxic tailings retention system (TRS), which was constructed in 1988, has historically been negligible (Read 1994; ODO 1995). However, the commissioning of four acid liquid evaporation ponds totalling 70 ha in 1995 resulted in an increase in waterfowl usage of the TRS and necessitated the development of a deterrent system (ODC 1996). The very low pH (pH < 1·5) of the tailings precludes the establishment of aquatic flora or fauna (Read & Pickering 1999) and hence waterfowl or other wildlife neither feed nor drink from these ponds. Ducks, coots and grebes, which retreat to the water when threatened, accounted for the majority of deaths. Although never recorded from the TRS, up to 3500 freckled duck Stictonetta naevosa, which is estimated as approximately one-sixth of their total population (Martindale 1986), occasionally inhabit the Olympic Dam region (Read & Ebdon 1998) and the protection of this species was a major impetus for developing an effective deterrent system at Olympic Dam.

image

Figure 1. Location of Olympic Dam and study localities

Download figure to PowerPoint

The aim of this paper is to describe a series of initiatives to minimize waterfowl use of toxic liquid storages.

Methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

Rationale

Three observations of waterbird behaviour guided the development of deterrents: nocturnal movements, diurnal predation and nomadism. Because many long-distance waterfowl movements occur at night (McNeil, Drapeau & Goss-Custard 1992) any non-illuminated visual structures, such as cables or netting, are unlikely to be efficient. In fact they may themselves cause injuries (Brown & Drewien 1995). Waterbirds are particularly vulnerable to diurnal predation (Green 1960; Czechura & Debus 1985), and wedge-tailed eagle Aquila audax, little eagle Hieraaetus morphnoides and peregrine falcon Falco peregrinus have been observed taking waterfowl, including ducks, swans and grebes, disturbed from ponds at Olympic Dam during the day. Therefore, even if they can be coerced to leave a toxic waterbody during the day, waterfowl will often retreat to the safety of the water after a short flight. Nomadism in Australian waterfowl means that habituation to successful deterrents is unlikely to be a problem, particularly when food rewards are not available.

An effective waterfowl deterrent for toxic ponds in arid Australia should therefore operate at night, should not result in physical injuries and could be repetitive without birds developing a tolerance.

Early trials

Illuminated and audial deterrents such as horns, shot-gun blanks, coloured lights, strobe lights and spotlights were trialed at the Roxby Downs sewage ponds at night. A bright, focused spotlight beam was most effective at scaring the majority of waterbirds from the ponds when held close to the water level. This increased the size of the illuminated zone on the water compared with when the light was elevated. Horizontally directed light also reflected less light onto low clouds and was unlikely to attract birds to the ponds (Howell, Laskey & Tanner 1954; Avery, Springer & Dailey 1978; Bjorge 1987).

Intermittent, as opposed to continuous, operation of the beacon was also advantageous because lights may attract birds (Draulans & van Vessem 1985; Hockin et al. 1992; Bertram 1995; Rohweder & Baverstock 1996) or insects, which in turn may attract diurnal birds to the site. The ‘shock value’ of a beacon that exposed waterfowl to short periods of illumination, interspersed with darkness, was also considered desirable as birds can readily habituate to regular, predictable stimuli (Hockin et al. 1992; Fox & Madsen 1997).

Design of prototype

A rotating beacon was chosen to deter waterfowl from a large area, rather than a series of spotlights for complete illumination of the ponds. Ideally the beacon had to be both in the centre of the waterbody and close to the water level, and hence a floating solar-powered beacon was developed.

Highly acid-resistant materials were required for the construction and tethering of the pontoon, power source and light in ponds with a pH range of 0·7–1·0 (Read & Pickering 1999). Glass, rather than plastic, solar cells were chosen and the aluminium borders of the solar panels were coated with EPIREZ 133AR acid-resistant epoxy binder. The electrical and mechanical components of the rotating beacon were isolated from the corrosive environment inside a stainless steel box fitted with rubber seals. Acid-resistant fibreglass grid off-cuts were used as the basis of the pontoon and were strapped to weld-sealed polyethylene pipes. The pontoon was held in position with 6-mm acid-resistant polyethylene rope.

Two time switches turned the light on and off at the desired intervals and a photoelectric cell restricted operation to night times, thus saving power and wear on the device. The spotlight was most effective at deterring waterfowl when rotating slowly, thus the motor was geared down to four revolutions per minute. Power-use calculations suggested that the battery and solar cell could run the beacon for 1 min every 10 min during the night, and still have sufficient power to allow for three consecutive cloudy days, a very rare occurrence at Olympic Dam (J.L. Read, personal observation).

Deterrent trial

The prototype was trialed on the Roxby Downs sewerage ponds, which consistently supported in excess of 100 waterfowl on a series of four ponds. These ponds were each rectangular, approximately 1 ha in size and mostly devoid of vegetation. Due to the vagaries of waterfowl movements and abundance in the region, the experiment compared waterfowl abundance on ponds with and without the deterrent at the same time, rather than before and after implementation of the deterrent (Brown & Drewien 1995). The rotating beacon was moved at random from pond to pond on different nights and the numbers and species of waterfowl on the ponds with and without the deterrent were recorded at dawn. The numbers of waterfowl on the pond with the deterrent and the mean count for the ponds without the deterrent were compared using paired t-tests for each waterfowl species for each of six monitoring nights.

Implementation of deterrent

Floating solar-powered beacons were exposed to acid spray and occasionally capsized on windy days. To avoid this problem, two to five rotating beacons were installed adjacent to mains power sources around the perimeter of each of the acid liquid ponds in the TRS. The solar-powered floating structures were still used on smaller ponds remote from mains power. Gas-powered sonic guns were also installed around the TRS to deter species such as gulls, terns and some waders, which fly during the day. These guns also operated at night and hence may have confounded evaluation of the lights in this field trial. Both live and dead waterfowl on the ponds were recorded each morning for the 12 months prior to and 24 months following the installation of the deterrents.

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

The intermittent rotating beacon significantly deterred ducks from the sewerage ponds (Fig. 1), with an overall 90% reduction in duck numbers. Occasional waterfowl that were unable to fly because they were apparently moulting or unhealthy, remained in the ponds with the deterrent. The small populations of wading birds such as masked lapwings Vanellus miles, black-fronted dotterels Charadrius melanops and red-necked avocets Recurvirostra novaehollandiae were neither deterred nor attracted by the beacon; however, it is of less concern that the deterrent was not effective for these species, which exhibit few casualties on the Olympic Dam Corporation TRS (ODO 1994, 1995; ODC 1996, 1997). The only abundant waterfowl species not effectively deterred in the sewer-pond trials was the hoary-headed grebe Poliocephalus poliocephalus (Fig. 2) which, with the less abundant Australasian grebe Tachybaptus novaehollandiae, dived under water when the spotlight was activated.

image

Figure 2. Total count of all ducks and the most abundant waterfowl species on deterrent ponds compared with the average count from the other three ponds. Significant differences tested by paired t-tests. NS, not significant, 0·01 < P < 0·001 **, 0·001 > P***).

Download figure to PowerPoint

Field trials during the 12-month period while the deterrents were being installed and modified showed that bird deaths were reduced to less than one-third of those recorded the previous year (ODC 1997). Nearly half of the deaths occurred in September 1996 (Fig. 3) when the deterrent system was largely disfunctional due to temporary maintenance problems. Death rates were reduced to one-sixth of these lower levels in the second year since installation from March 1997 to February 1998 (Fig. 2), when the system was fully operational. Hoary-headed grebes accounted for four of the 15 casualties since the installation of the deterrents.

image

Figure 3. Bird deaths recorded from the Olympic Dam TRS. High losses in early 1996 prompted the development of deterrents, and those in September 1996 coincided with a low efficiency of the deterrent system due to maintenance problems.

Download figure to PowerPoint

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

The rotating beacon was a significant deterrent for most waterfowl species and reduced total waterfowl abundance by more than 90% during trials. Interspecific differences in the response of waterfowl to disturbance, which were evident in this study, have also been recorded elsewhere (Hill et al. 1997; Madsen 1998). Despite this variability, efficacy of this deterrent compares favourably with other mitigatory measures designed to deter birds from waterbodies, which ranged from 71% to 85% (Stickley, Mott & King 1995; MEM 1996b), and those which reduce waterfowl deaths from collisions with power lines, which typically range from 45% to 63% (Brown & Drewien 1995).

The success of the intermittent beacon and sonic gun deterrent system on the ODC TRS can only be measured by long-term monitoring of its ability to dissuade the infrequent use of toxic ponds by large numbers of waterfowl and the durability of the components in the acidic environment. Unlike the controlled trial experiment, stochastic waterfowl movements confound estimates of the efficacy of the deterrent system on the TRS. Nevertheless, the mean monthly death rate at the TRS in the 17 months since October 1996, where deterrents were fully operational, was 0·9 birds per month compared with the average of 9·5 birds per month recorded prior to the introduction of the deterrent system. Comparison of summer month casualties in the year prior to and following implementation of the deterrents, reveals that despite similar local waterfowl populations, a reduction from 79 to five reported deaths was observed, which provides further evidence of the effectiveness of the system (Paton 1997).

Several alterations may enhance the effectiveness of this waterfowl deterrent system, and the value of these modifications may vary under different conditions and at different locations. Spotlight size, rotation rate, operating frequency and number of devices could all be modified to optimize performance of the deterrent system. Incorporation of an underwater sonic alarm may deter grebes, and intermittently operating buzzers may discourage birds from perching, defaecating or even nesting on the devices. Use of harassment, alarm and distress calls may also increase the efficacy of the deterrent for some species, although care must be taken not to encourage more individuals of species that use the water as a defensive refuge, such as grebes and coots, into the toxic ponds.

Effective deterrence of waterfowl from toxic waterbodies should involve a multifaceted site-specific management approach. Waterfowl use of toxic waterbodies should decrease if nearby safe waterbodies are made more attractive for nomadic individuals. Possible approaches include protecting clean alternative waterbodies from disturbance by humans or waterfowl predators, provision of beaches, shallow banks or islands for roosting (Hockin et al. 1992; Hill et al. 1997), and possibly encouraging aquatic vegetation in some regions (Ward & Andrews 1993). Decoy ducks may further enhance the attraction of clean waterbodies because foraging ducks attract flying conspecifics (Pöysä 1991). However, care must be taken not to exacerbate the numbers of waterfowl interacting with toxic waterbodies if breeding of waterfowl in decoy ponds is encouraged.

Large dams attract more waterfowl than smaller dams (Leach 1994) and hence if the most toxic elements of tailings storages are kept small they may attract fewer birds than larger storages. Likewise, any additional method of rendering toxic dams less attractive to waterfowl than decoy waterbodies, such as engineering steep, lined banks which discourage roosting and increase human activity and noise levels, should help to alleviate waterfowl use.

Acknowledgements

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

WMC Resources Ltd (Olympic Dam Corporation) supported and funded this study as part of their Environmental Management and Monitoring Programme. Bruce Christian, Andy Hall, Chris Pratt, Mick Evans and Ian McClennan assisted with the development of the deterrent, and Kelli-Jo Lamb assisted with initial trials. Thanks to the many personnel from mining and agricultural operations who provided useful insights into the effectiveness of different deterrents that they trialed. Nick Reid and David Paton provided valuable criticisms of drafts of this manuscript.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References
  • Avery, M.L., . Springer, P.F. & Dailey, N.S. 1978 Avian Mortality at Man-Made Structures: An Annotated Bibliography. United States Fish and Wildlife Service, Washington, DC.
  • Badman, F.J. 1987. Boredrains and the Birds of Inland South Australia. Nature Conservation Society of South Australia, Adelaide, Australia.
  • Bertram, D.F. 1995 The role of rats and commercial fishing in the decline of Ancient Murrelets on Langara Island, British Columbia. Conservation Biology, 9, 865872.
  • Bjorge, R.B. 1987 Bird kill at an oil industry flare stack in northwest Alberta. Canadian Field-Naturalist, 101, 346350.
  • Braithwaite, L.W. & Stewart, D.A. 1975 Dynamics of water bird populations on the Alice Springs sewerage farm, NT. Australian Wildlife Research, 2, 8590.
  • Briggs 1992 Movement patterns and breeding characteristics of arid zone ducks. Corella, 16, 1522.
  • Brown, W.M. & Drewien, R.C. 1995 Evaluation of two powerline markers to reduce crane and waterfowl collision mortality. Wildlife Society Bulletin, 23, 217227.
  • Czechura, G.V. & Debus, S.J.S. 1985 The black falcon Falco subniger: a summary of information and comparison with the brown falcon Falco berigora. Australian Bird Watcher, 11, 8091.
  • Davidson, N.C. & Rothwell, P.I. 1993 Disturbance to waterfowl on estuaries. Wader Study Group Bulletin, 68. Cited in Madsen, J. (1995) Impacts of disturbance on migratory waterfowl. Ibis, 137, 6774.
  • Draulans, D. & Van Vessem, J. 1985 The effect of disturbance on nocturnal abundance and behaviour of grey herons Ardea cinerea at a fish farm in winter. Journal of Applied Ecology, 22, 1927.
  • Fox, A.D. & Madsen, J. 1997 Behavioural and distributional effects of hunting disturbance on waterbirds in Europe: implications for refuge design. Journal of Applied Ecology, 34, 113.
  • Green, H.H. 1960 Swamp harrier attacking coots. Australian Bird Watcher, 1, 116117.
  • Hill, D., Hockin, D., Price, D., Tucker, G., Morris, R. & Treweek, J. 1997 Bird disturbance: improving the quality and utility of disturbance research. Journal of Applied Ecology, 34, 275288.
  • Hockin, D., Ounsted, M., Gorman, M., Hill, D., Keller, V. & Barker, M.A. 1992 Examination of the effects of disturbance on birds with reference to its importance in ecological assessments. Journal of Environmental Management, 36, 253286.
  • Howell, J.C., Laskey, A.R. & Tanner, J.T. 1954 Bird mortality at airport ceilometers. Wilson Bulletin, 66, 207215.
  • Kingsford, R.T. & Porter, J.L. 1993 Waterbirds of Lake Eyre. Biological Conservation, 65, 141151.
  • Lawler, W., Kingsford, R., Briggs, S.V. & Milkovits, G. 1993 Movements of grey teal Anas gracilis from a drying, arid zone wetland. Corella, 17, 5860.
  • Leach, G.J. 1994 Effects of dam size on waterbirds at farm dams in south-east Queensland. Corella, 18, 7782.
  • Madsen, J. 1998 Experimental refuges for migratory waterfowl in Danish wetlands. II. Tests of hunting disturbance effects. Journal of Applied Ecology, 35, 398417.
  • Martindale, J. 1986. The Freckled Duck – an RAOU Conservation Statement. RAOU Report 22. Royal Australasian Ornithological Union, Melbourne, Australia.
  • McNeil, R., Drapeau, P. & Goss-Custard, J.D. 1992 The occurrence and adaptive significance of nocturnal habits in waterfowl. Biological Reviews of the Cambridge Philosophical Society, 67, 381–419 Cited in McNeil, R., Diaz D.O., Linero, I.A. & Rodriguez S.J.R. (1995) Day and night-time prey availability for waterbirds in a tropical lagoon. Canadian Journal of Zoology, 73, 869878.
  • MEM 1996a Bird balls. Mining Environmental Management, 4, 23.
  • MEM 1996b Preventing bird deaths. Mining Environmental Management, 4, 1011.
  • Minerals Council of Australia 1996. Tailings Storage Facilities at Australian Gold Mines. Submission to the Senate Environment, Recreation, Communications and the Arts References Committee, Canberra, Australia.
  • Norman, F.I. 1979 Results from banding Eurasian coots in Victoria. 1953–77. Corella, 3, 7376.
  • ODC 1996 Environmental Monitoring and Management Programme. Annual Report 1/03/1995–28/02/1996. WMC Resources (Olympic Dam Corporation), Olympic Dam, South Australia.
  • ODC 1997 Environmental Monitoring and Management Programme. Annual Report 1/03/1996–28/02/1997. WMC Resources (Olympic Dam Corporation), Olympic Dam, South Australia.
  • ODO 1994 Environmental Management Programme. Annual report 1/03/1993–28/02/1994. WMC Resources (Olympic Dam Operations), Olympic Dam, South Australia.
  • ODO 1995 Environmental Management Programme. Annual report 1/03/1994–28/02/1995. WMC Resources (Olympic Dam Operations), Olympic Dam, South Australia.
  • Paton, D.C. 1997. Assessment of the Bird Management Program for Acidic Tailings Dams at the Olympic Dam Mining Site. Unpublished report. Adelaide University, Adelaide, Australia.
  • Pöysä, H. 1991 Effects of predation risk and patch quality on the formation and attractiveness of foraging groups of teal, Anas crecca. Animal Behaviour, 41, 285294.
  • Read, J.L. 1994 A retrospective view of the quality of the fauna component of the Olympic Dam Project Environmental Impact Study. Journal of Environmental Management, 41, 167185.
  • Read, J.L. & Ebdon, R. 1998 Waterfowl of the Arcoona Lakes; an important arid-zone wetland complex. Australian Bird Watcher, 17, 234244.
  • Read, J.L. & Pickering, R. 1999 Ecological and toxicological effects of exposure to an acidic, radioactive tailings storage. Environmental Monitoring and Assessment, 54, 6985.
  • Rohweder, D.A. & Baverstock, P.R. 1996 Preliminary investigation of nocturnal habitat use by migratory waders (Order Charadriformes) in northern New South Wales. Wildlife Research, 23, 169184.
  • Ryan, P. & Shanks, B. 1996 Tailings dams. The Bird Observer, July, 1996, 710.
  • Stickley, A.R., Mott, D.F. & King, J.O. 1995 Short-term effects of an inflatable effigy on cormorants at catfish farms. Wildlife Society Bulletin, 23, 7377.
  • Ward, D. & Andrews, J. 1993 Waterfowl and recreational disturbance on inland waters. British Wildlife, 4, 221229.

Received 15 April 1998; revision received 18 December 1998