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The Barn Owl Trust

Conserving the Barn Owl and its Environment

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The problem with rat poison

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The vast majority of rat poisons used these days (such as Neosorexa and Slaymor) are highly toxic SGARs - 'Second Generation Anticoagulant Rodenticides' ...




The problem with rats:
A great many EU member states are opposed to the use of SGARs (rat poison) and in 2013 the prospect of an EU-wide ban sent a shock wave through the Rodenticide and Rodent Control industries; particularly because there are no new rodent poisons on the horizon. Rats are clearly a threat to human health and their colonisation of some small UK islands with the devastating consequences for ground nesting seabirds, shows that they can do real damage to some of our native wildlife too. It is an inescapable fact that rats need to be controlled.

Poisoning is set to continue:
Despite the fact that poisoning is NOT the only way to deal with many infestations, the use of poisons is set to continue. Indeed the EU has now allowed member states to continue licencing the use of SGARs for periods of up to 5 years provided that certain criteria are met including the minimisation of environmental risks through mitigation measures.

To date, mitigation measures such as use-restriction regulations and statutory safety noticeson SGAR products have failed to prevent: 1) increases in wildlife contamination and, 2) increases in resistance* to SGARs in some parts of the UK.

*resistance is explained below

Most Birds of Prey are contaminated:
The extent to which rodenticides have contaminated small-mammal predators is shocking. Latest results from the Predatory Bird Monitoring Scheme show that ALL of the Kestrels they examined in 2011 were contaminated along with 94% of Red Kites. The proportion of Barn Owls contaminated reached its highest level in 2010: 91%! And we are not just talking about a restricted area. The analysed corpses were sent in by the public from across Britain. In other words, virtually the entire populations of these three sentinel species have been feeding on rodents that contain rat poison.

The BIG question; are sublethal doses having any effect?:
As the rodenticide industry is quick to point out, there is no evidence that sub-lethal doses have any effect on Barn Owls. But in fact, there is no evidence that it is NOT affecting them. Nest cameras such as those used by BBC Springwatch have revealed marked differences in the behaviour of breeding Barn Owls and it is clear that some are far more energetic than others. We know that safe medicinal doses of the anti-coagulant Warfarin can have side effects in humans including nausea and that warfarin is 100 to 1,000 times less acutely toxic than the poisons found in Barn Owls. Even if behavioural changes are slight, with 76% of farms using highly toxic rodenticides and up to 91% of Barn Owls contaminated, the effect could be dramatic because almost the entire population is affected".


Resistance to SGARs is an increasing problem:
'Resistance' means rats are feeding on SGARs and surviving. In the worst-affected area (South Midlands down to Berkshire) Local Authorities and other Pest Control Operators have been seeking special permission from HSE (Health and Safety Executive) to use the strongest SGARs (those only licenced for indoor use) to control rats in open areas accessed by the public. So far, none of these applications have been granted and Authorities have been unable to discharge their responsibilities for protecting public health.

What the Barn Owl Trust is doing:
Against a background of EU pressure, increasing wildlife contamination, and rising resistance to SGARs amongst rats, a major shake-up of SGAR use (licencing, mitigation) is due. It’s happening now.

Hard-hitting presentation at the HSE SGAR Seminar: In 2013 BOT applied pressure during the HSE's Stakeholder Engagement and subsequently attended HSE's SGAR Seminar in Merseyside where our Senior Conservation Officer gave a hard-hitting presentation to representatives of Rodenticide Manufacturers, Pest Controllers, and Government Regulators (Read a PDF version by following the link >).

Published Article: We were subsequently invited by the Chartered Institute of Environmental Health to submit an article for publication in Pest Control News.
You can read our article by following the link in the right hand sidebar> OPEN DOCUMENT THEN SCROLL DOWN TO PAGE 16.

Petitioned the Minister responsible for pesticides. See the detail of our Petition


Background to the rat poison problem:

Within the UK food industry there is an ever-increasing demand from consumers, supermarkets and processing companies for high quality and safe food. This has led to stricter quality assurance requirements and the need for more effective control of pests, such as rodents (rats and mice) on farms. The biggest farm assurance scheme in Britain is the 'Red Tractor'. Farmers supplying these schemes are required to have a Rodent Control Programme in place and many assume that this means using poisons constantly when, in fact, this is not good practice. Permanent and preventative baiting are big money-maker for the Rodent Control Industry but also a major cause of unwanted poisoning.

It is well known that Barn Owls and other predators sometimes prey on rodents that have eaten poison and wild birds and non-target mammals sometimes eat the poison itself need. In addition children and domestic pets are at risk.


The majority of rodent poison, or rodenticide, in the UK usually takes the form of grain or pellets to which the poison has been applied. There are two main types of cumulative rodenticide: first generation (multiple dose) such as Warfarin, mainly used in areas where rats demonstrate little resistance, and more toxic second generation (single dose) poisons. The majority of rodent control in the UK uses second generation.


There is no doubt that Barn Owls across the UK are widely exposed to the risk of secondary poisoning and that individual Barn Owls die as a result. Rodenticides almost certainly have a detrimental effect on Barn Owl populations in the UK and this is an issue of serious concern for Barn Owl conservation.

slaymore bucket

Rat poison labelling:

All rodenticides are toxic and can kill Barn Owls; however the instructions provided on the containers do not mention the risks or explain how secondary poisoning happens. Labelling generally gives the impression that provided baits are kept covered, and dead rodents disposed of, there is little or no risk to predatory birds. Unfortunately no amount of bait covering will prevent secondary poisoning (for a full explanation and list of rodenticides, see the Trust's free leaflet on Rodent Control - download from the LHS menu).


The Barn Owl Trust's information campaign:

Since 1989 the Barn Owl Trust has provided both farmers and the public with information on controlling rodents without using poisions and (when neccessary) how to choose the least toxic poison. We have helped to campaign for improved labelling on all rodenticide products and this led to a meeting with Dr Alan Buckle, chairman for the Campaign for Responsible Rodenticide Use, a body set up by the rodenticide industry. Since 2006 the words "Harmful to Wildlife" have been added to rodenticide labels - a small step in the right direction.

For further information download our "Rodent Control" leaflet from the link on the right.

The Trust's work - rodenticide advisory

There's more information on this topic in the Barn Owl Conservation Handbook

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Barn Owl Trust staff and volunteers
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