Action: Use coloured baits to reduce accidental mortality during predator control
Key messagesRead our guidance on Key messages before continuing
Most birds (unlike most mammals) are visual hunters and foragers, meaning that strangely coloured baits may not be taken as readily, and so using them during eradication programmes may reduce incidental mortality.
Supporting evidence from individual studies
A review of three replicated, controlled trials in Day County, South Dakota, USA, and another in Routt County, Colorado (Kalmbach & Welch 1946), in 1945, found that bird assemblages (mainly songbirds and doves) took a higher proportion of uncoloured grain (88% taken) than of yellow (73%) or green (23%) grain, and when uncoloured was not available, birds took more yellow (87% and 15% in two sites) than green (39% and 9%). In addition, more dead birds were found with uncoloured poison grain in their stomachs than with yellow. Very few birds were found with green grain.
A replicated, randomised and controlled, ex situ experiment (Nicholls 2000) found that consumption of day-old chicks by 33 American kestrels Falco sparverius was greatly reduced by dying chicks green or blue, with no birds consuming blue-dyed chicks and two birds also avoiding green-dyed chicks. All birds reduced food intake significantly. Treating chicks with two repellents (discussed in ‘Use repellents on baits’) did not affect consumption in addition to dyeing. This study is also discussed in ‘Use aversive conditioning to reduce nest predation’.
A replicated, randomised and controlled trial in Adelaide Zoo, South Australia (Johnston & McCarthy 2007), found that dyeing food (minced beef, fruit and ‘Wombaroo insectivore mix’ – a commercially available food mix) blue had no effect on its consumption by six captive bush stone-curlews Burhinus grallarius over a ten day period.
- Kalmbach E.R. & Welch J.F. (1946) Colored rodent baits and their value in safeguarding birds. The Journal of Wildlife Management, 10, 353-360
- Nicholls M.K. (2000) An evaluation of methyl anthranilate, aminoacetophenone, and unfamiliar coloration as feeding repellents to American kestrels. J Raptor Res, 34, 311-318
- Johnston G. & McCarthy P. (2007) Susceptibility of Bush Stone-curlews (Burhinus grallarius) to sodium fluoroacetate (1080) poisoning. Emu, 107, 69-73