Action Synopsis: Bird Conservation About Actions

Use visual and acoustic ‘scarers’ to deter birds from landing on pools polluted by mining or sewage

How is the evidence assessed?
  • Effectiveness
  • Certainty
  • Harms

Study locations

Key messages


About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. A trial of an early design of radar-activated system (that triggered a stereo, fire alarm, propane cannons and firecrackers) aimed at scaring birds from mine tailing facilities in Nevada, USA (Weber &Filas 1993), showed that the system had promise. Subsequent trials of the system are described in (Johansson et al. 1993, Stevens et al. 2000, Ronconi et al. 2004).

    Study and other actions tested
  2. Two controlled experiments at a 18.2 ha desulfurisation pond in north-central USA (Johansson et al. 1994) found that significantly fewer birds landed on ponds where a scaring system was in place (autumn and spring 1993-1994: 17 birds used a pond when the system was active for 48 hour periods vs. 125 when it was inactive for 48 hour periods; autumn 1994: 16 of 43,964 bird landings, 2% of the expected number, occurred on the pond with the system).  The radar-activated system (a BirdAvert© system) used various deterrents (broadcasts of recordings of e.g. dogs barking, guns firing and falcons screaming; strobe light; plastic falcons with flapping wings, and automated scarecrows).

    Study and other actions tested
  3. A randomised, replicated and controlled trial in South Australia in 1996-7 (Read 1999), found that the number of wildfowl on sewerage ponds was 90% lower when a slowly rotating beacon with an intermittent, low-angled beam was floated in the centre of the ponds, compared to control ponds with no beacon (average of approximately 2 ducks/night on experimental ponds vs. 36 ducks/night on control ponds). There was no change in the behaviour of waders, and grebes dived, rather than dispersing. A follow-up, before-and-after experiment found that the number of wildfowl and hoary-headed grebes Poliocephalus poliocephalus on toxic and acidic tailing ponds were over 66% lower in the 12 months following the installation of a slowly rotating beacon with an intermittent, low-angled beam that floated in the centre of the ponds, compared to the 12 months before installation. Over half of the casualties were when the device was not fully operational and mortality rates were reduced to one-sixth of post-installation levels in the 12 months after the device became fully operational. Of the 15 mortalities following installation, four were hoary-headed grebes.

    Study and other actions tested
  4. A controlled trial at the Jim Bridger Power Plant, Wyoming, USA, in 1996-7 (Stevens et al. 2000) found that waterfowl were 12.5 times less likely to fly over and 4.2 times less likely to land on two ponds (36.5 and 80.8 ha) when a radar-activated deterrent system was used, compared to an adjacent freshwater pond (93.2 ha) with no deterrent; non-waterfowl were seven times less likely to land. Bird rescues per year decreased by more than 400 (>70% fewer rescues) in the first year of full operation. Between 685 and 714 rescues occurred in preceding years, 859 in the transition year, and 210 in the first year of full operation (mortality reduced by more than 77% relative to previous years). When flying birds were detected, the system broadcast alarm and distress calls of a variety of animals, let off ‘screamer’ cartridges, and finally a bird aerosol tear gas was triggered (only used if birds were still detected after initial deterrents were activated).

    Study and other actions tested
  5. A replicated, controlled trial at two sites in San Francisco Bay, California (USA) found that the Breco Bird Scarer (an orange buoy designed to drift with an oil slick) did not alter waterbird behaviour when it was broadcasting sounds as opposed to non-broadcasting (Whisson & Takekawa 2000). The buoy broadcasts up to 30 different sounds at up to 130 dB at 1 m, at varying intervals (30 sec to 5 min, dependent on how programmed). Alternating 2-day treatment (device ‘on’) and control (‘off’) periods were conducted. No significant deterrent effect was noted on numbers of three common wintering duck species (greater and lesser scaup Aythya affinis and A. marila, surf scoter Melanitta perspicillata) and all other waterbirds.

    Study and other actions tested
  6. A literature review (Ronconi et al. 2004) suggests that the use of radar-activated deterrent systems both increases effectiveness at deterring waterbirds at contaminated sites and reduces the cost necessary (compared to conventional methods) to achieve success.

    Study and other actions tested
  7. A randomised, replicated and controlled trial at a tar sands mine in Alberta, Canada, in 2003 (Ronconi & St Clair 2006), found that a lower proportion of 372 groups of birds landed on three tailing ponds when an on-demand bird deterrent system was used, compared to control periods when the system was not used or to periods when industry standard deterrents were used (1-5% of bird groups landing with on-demand system vs. 5-16% for industry standard and 8-23% for controls). The on-demand system used radar-activated propane cannons, high-intensity strobe lights, moving models of peregrine falcons Falco peregrinus and broadcasts of peregrine calls; the industry standard system used human effigies and cannons that fired at random intervals. A further trial found that birds were significantly more likely to change direction when propane cannons were fired on demand, compared to when a peregrine model was moved and peregrine calls played (11% of 28 bird groups responded when peregrine models were activated vs. 40% of 30 bird groups responding when cannons were used).

    Study and other actions tested
Please cite as:

Williams, D.R., Child, M.F., Dicks, L.V., Ockendon, N., Pople, R.G., Showler, D.A., Walsh, J.C., zu Ermgassen, E.K.H.J. & Sutherland, W.J. (2020) Bird Conservation. Pages 137-281 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.


Where has this evidence come from?

List of journals searched by synopsis

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Bird Conservation

This Action forms part of the Action Synopsis:

Bird Conservation
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What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

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