A Government-approved scheme to see if oral contraception can be used to cut the number of Britain’s grey squirrels is producing hopeful results, researchers have said.
Environment minister Lord Benyon described invasive grey squirrels as “pests” who cause “untold damage in the British countryside”.
He said a new way could be found to deal with them through work being done by the UK Squirrel Accord (UKSA) and the Animal and Plant Health Agency (Apha).
Lord Benyon said that “important research on oral contraception shows promising signs that could help to eradicate the grey squirrel in the UK in a non-lethal way, as well as helping to recover our beloved red squirrel”.
UKSA-funded laboratory trials have been looking into an oral contraceptive as a non-lethal way to manage grey squirrels along with special feeding sites that can only be accessed by them.
Vital progress has been made in the effort to find ways to isolate the squirrels so they may then be able to take the contraceptive, researchers say.
Apha says it has a feeder with a weighted door that excludes most other wildlife while allowing more than 70% of local grey squirrel populations to get in and eat from them.
Apha is testing different methods of keeping red squirrels out of the feeders, so contraceptives could be used in areas where there are both types of squirrel.
Body weight could be key to helping to distinguish between greys and reds, according to the research which currently does not use the contraceptive in the natural landscape.
Further testing and landscape-scale field trials are being carried out.
UKSA now has the funds to cover the research of the grey squirrel fertility control project.
Grey squirrels cause damage to woodlands by stripping bark from trees aged between 10-50 years, the young trees in a forest. They are also one the main reasons for local extinctions of red squirrels in large areas of the UK.
They target broad-leafed varieties, including oak, which are ecologically important because they support so many other species. It is estimated the UK is home to around three million of these invasive rodents.
Lord Benyon said the squirrels are to blame for wrecking fledgling broad-leaf trees like oak by stripping bark, and “disrupting the delicate balance of nature and biodiversity, whilst diminishing our ability to tackle climate change”.
Lord Kinnoull, chairman of the UK Squirrel Accord and Red Squirrel Survival Trust, said: “This is a vital milestone on the road to enabling forestry to play fully its part in the climate battle, while preserving our native broadleaf trees and allowing our native red squirrels to return.”
Gideon Henderson, the chief scientific adviser at the Department of Environment, Food and Rural Affairs, said: “Fertility control can be an effective method complementing other approaches to wildlife management. This UK Squirrel Accord & Defra funded study aims to produce an immuno-contraceptive that can be orally administered to grey squirrels through a species-specific delivery mechanism.
“This innovative research has great potential to provide an effective, easily-applied and non-lethal method for managing grey squirrel populations. It will help red squirrels – native to the UK – expand back into their natural habitats, as well as protecting UK woodland and increasing biodiversity.”
Vanessa Fawcett, of the Red Squirrel Survival Trust, said: “Without effective conservation management, red squirrels could face further local extinctions across the UK.
“Research into developing an oral contraceptive for the grey squirrel is at an advanced stage. We are deeply grateful to all those who supported us so far on our journey to offer a new solution to effectively manage grey squirrel populations.”
Rebecca Isted, of the Forestry Commission, said she was “optimistic these trials could eventually lead to a significant change of approach in the management of these animals”.
She added that the Forestry Commission is updating the Government’s Grey Squirrel Action Plan, and will later set out its aims to better understand and manage the negative impacts of grey squirrels.