Developments made with grey squirrel contraception
Grey squirrels can spread harmful diseases to endangered red squirrels.
The University of Edinburgh’s Roslin Institute has marked key developments in the production of contraceptives for wild grey squirrels.
Research, led by the government’s Animal and Plant Health Agency (APHA), has resulted in an edible contraceptive that could reduce the threat grey squirrels pose to red squirrels.
Grey squirrels are considered an invasive species, with no protection under the Wildlife and Countryside Act (1981). As well as taking over habitats, they can also spread harmful diseases to the endangered red squirrel.
APHA has tested a new vaccine, contained in a capsule, which is made from plant pollen spores by Sporomex.
The edible vaccine triggers an immune response, causing the body to produce antibodies against reproductive hormones. This then interferes with the reproductive system and causes infertility.
It is designed to have minimal environmental impact, so can be added to food bait.
The contraceptive has already been tested on rats in a laboratory setting, which became infertile after ingesting the contraceptive as a vaccine. They also have an effect on captive grey squirrels.
The next stage of the process will see APHA collaborate with the Roslin Institute to increase the scale and duration of the vaccines while keeping them suitable for taking into the wild.
Experts from the Roslin Institute have also provided information on immune response measurements. This will aim to ensure a safer and more ethical method to population control.
Elsewhere, efforts are underway to create a feeding station accessible only to grey squirrels, including weight-sensitive doors.
Bex Pinkham, a spokesperson from APHA, said: “I’m really encouraged by the progress we’ve made in our research so far as part of this important partnership project.
“These breakthroughs are a positive step forward towards a grey squirrel management tool that will mean so much for our UK woodlands.”
Prof Jayne Hope, from the Roslin Institute, added: “We are pleased to be involved in this exciting project that could enable the development of a manageable, humane solution for control of populations such as grey squirrels”
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Companies marketing medicines for small pets exempt from authorisation must submit their annual return to the Veterinary Medicines Directorate (VMD) by 30 November 2026.
