Birdwatch News Archive

It seems all pesticides have some kind of ecological 'knock-on' effect, as American Kestrels are now finding out. Photo: Steve Hillebrand (
It seems all pesticides have some kind of ecological 'knock-on' effect, as American Kestrels are now finding out. Photo: Steve Hillebrand ( image

American raptor poison fears

Posted on: 14 Mar 2011

An unrestricted new pesticide has been shown to kill birds of prey in America, reviving bad memories of the DDT crisis in the 1960s.

New research on American Kestrels has shown that the rodenticide diphacinone - widely used as a substitute for rodenticides now banned or restricted by state law - shows significant build-up in the birds of prey at the top of the food chain, resulting in rapid fatalities.

American Kestrels that ingested more than 300 mg per kg of body weight died within 23 hours; others consuming a dose of 118 mg per kg also died, lasting no more than 47 hours. Lower doses resulted in survival. It is not known if the rodenticide affects breeding success like DDT, but any dose greater than 79 mg/kg appears to be eventually lethal for the small raptors.

The poison is developed to be tasteless and have a delayed action, which means that the live-prey eating kestrels are highly likely to eat contaminated mice and rats, as they will still be active after eating poisoned bait. Diphacinone is an anticoagulant which causes profuse unstoppable bleeding. Recovered kestrel corpses showed evidence of internal bleeding, though haemorrhaging was present even at non-lethal doses.

Using American Kestrel as surrogates for less common raptors, the study showed that protection limits for birds of prey need to be lower than the gamebirds previously used a surrogates. Rodenticides have also been found to be present in French, British and Canadian birds of prey, with possibly derogatory effects on populations exposed to the chemicals.

Reference: Rattner, B, Horak, K, Warner, S, Day, D, Meteyer, C, Volker, S, Eisemann, J, and Johnston, J. 2011. Acute Toxicity, Histopathology, and Coagulopathy in American Kestrels (Falco sparverius) Following Administration of the Rodenticide Diphacinone. Environmental Toxicology and Chemistry DOI:10.1002/etc.490


Your Comments

Tell us what you think...

You must be logged in to leave a comment. You can log in here.
If you don't have a user account please register.

Other News

Breeding season grim up north

Posted: 01 Dec 2015
British Trust for Ornithology surveys have shown that despite an overall productive breeding season in Britain, the north has fared badly in contrast.

Read more…

Shocking increase in Amazon deforestation

Posted: 30 Nov 2015
The Worldwide Fund for Nature has warned the Brazilian government that it needs to boost conservation efforts, after damning new deforestation figures of 16 per cent were published.

Read more…

Two in the bush

Posted: 30 Nov 2015
A south-east Asian Locustella bush warbler has been found to consist of cryptic species after analysis of its songs, biometrics and DNA.

Read more…

Birds carry the news on environmental decline

Posted: 29 Nov 2015
Birds are the great messengers of the declining state of our environment, according to a newly published BirdLife study.

Read more…

Europe must do more to help threatened African wildlife

Posted: 28 Nov 2015
Conservationists have welcomed the launch of a new European plan to help protect declining wildlife in Africa.

Read more…

  2 3 4 >