Squirrels are quite pesky animals, which has led the government in the United Kingdom to devise a plan to use oral contraceptives to control the grey squirrel population.
Scientists have been making good progress on the mass birth control plan and are hoping to put the test in field trials shortly. The plan involves luring grey squirrels into feeding boxes only they can access, using pots containing hazelnut spread. These will be spiked with contraceptives.
Environment minister, Lord Benyon, said the project could help eradicate the grey squirrel in the U.K. without killing them. It should reduce the “untold damage” grey squirrels do to woodland ecosystems and to native red squirrel populations.
According to the government scientists leading the research on this contraceptive, both male and female grey squirrels will be infertile if they consume the vaccine as it prompts the immune system to restrict the production of sex hormones. It should be ready to deploy in the wild within two years.
Grey squirrels were first introduced from North America in the late 19th century and have since thrived in the U.K. There are around 2.7 million grey squirrels in the country, which are known for damaging woodlands by stripping bark from trees to get at the nutritious sap beneath. The animals prefer young trees and often favour broadleaf species like oak, beech, sweet chestnut, and sycamore.
Grey squirrels have also driven the U.K.’s native red squirrel to the verge of extinction across much of the country, with only 15,000 of the species remaining.
The more traditional way of managing the grey squirrel population is by culling them. This has limited effectiveness since grey squirrels breed rapidly and populations can recover quickly. Even with over a century of culling programmes, they have failed to reduce the grey squirrel population.