Bird expert calls for new incentives to deter use of rat poisons

Damian McCarney
In Cavan County Museum

A bird conservationist believes that agri-environmental payments could be used to encourage farmers to use rat poisons responsibly, in a bid to reduce risk to our birds of prey.
John Lusby made his comments during a visit to Cavan County Museum, Ballyjamesduff on Thursday night at which he explained the potential risk of such poisons on raptors, or birds of prey.
Mr Lusby, a raptor conservation officer with Birdwatch Ireland, is actively involved in monitoring the numbers of raptors such as kestrels, long-eared owl, barn owls, and merlins; the first two of which are prevalent in County Cavan.
Birdwatch Ireland accept that, when used responsibly, certain poisons, also known as rodenticides, can be effective in tackling rat and mice infestations. However, it appears the poisons are impacting on wildlife beyond rodents. Birds of prey do not scavenge, but their diet consists primarily of small mammals. Rodenticides often do not cause the rats and mice to die for a number of days; leaving the raptors exposed by preying on rodents which have ingested the poison but not yet died.
Mr Lusby believes that an awareness campaign to highlight possible, unforeseen consequences is required.
“Nobody intentionally wants to have a negative impact on barn owls or other raptors, so a large part of it is making people aware of that; and that’s what we are trying to do now. We have set up a scheme called the ‘Campaign for Responsible Rodenticide Use’ which we are running training courses through, and trying to make people aware of the situation, and the best ways to use the poisons if they feel they have to use the poisons.”
Birdwatch Ireland’s website outlines that “toxicology analysis of 69 barn owls collected between 2006 and 2011 revealed that over 80% had detectable residues of the four main toxic chemicals used in second-generation rodenticides. This high percentage of birds which tested positive for the poisons is similar to comparable studies in the UK; however, Irish barn owls had significantly higher concentrations of the poisons in their systems.”
Given the difficulty in conducting studies on wild birds, it is not known definitively what impact the poisons are having either at individual level or population level.
“More research needs to be done to figure out the extent of the problem,” accepts Mr Lusby. “The only species we’ve looked at so far has been the barn owl in terms of assessing actual exposure.
“I would like to see the inclusion of best practice rodenticide use incorporated into things like agri-environemnt schemes, basically to increase awareness through that, and to give farmers an incentive to change their approach to how rodents are controlled. I think that will be the best way to bring people on board.”

Realistic
Mr Lusby accepts that farmers, and others, do need to tackle rodent infestations, but advises that the first step should be to prevent the rats becoming established.
“We are realistic coming from the point of view that rodents have to be controlled, because there are many issues in terms of human health, the spread of disease, and contamination of foodstuffs...
“There are a lot of steps you can take before resorting to rodenticides, such as trying to make a particular area less suitable for rodents, removing food sources, blocking off entrances into farm buildings, even using natural control methods like trapping, like using cats in certain situations, encouraging barn owls is a great way because they feed to such an extent. Historically, before rodenticides, barn owls were very much known as ‘the farmer’s friend’ because of that role they played as natural rodent control.”
The remnants of this ‘friendship’ between owls and farmers can still be seen in “owl windows” in some old stone sheds to encourage birds to nest in lofts spaces.
“Before the days of rodenticides they were the best means of keeping rat and mice populations in a farmyard under control so they are absolutely no threat to farm practices and livestock, in fact they are beneficial to have around. We have done a lot of work, putting up nest boxes in sheds on active farms, and that has proved very positive from feedback we get from farmers in terms of the impact the birds have on rats and mice, and even just to have them around - they are iconic species. To see them more in the countryside would be positive for everyone.”

Assessment
If rodenticides are deemed necessary, Mr Lusby advises that farmers first conduct a risk assessment, decide upon the number of bait points required, minimise the quantity of poison used, and monitor the outcome.
“Particularly important is to remove carcases of rats, because rats or mice which consume the poison and die, if they are left exposed to scavengers, then obviously they contain a lot of residue of the poison and the poisons can accumulate in the food chain in that manner.”

For more on the ‘Campaign for Responsible Rodenticide Use’, and advice on attracting barn owls, see www.birdwatchireland.ie