Birth control to be used on squirrels across UK

Source: unknown (via The Sunday Post)
Without this intervention to reduce the population of grey squirrels, it is worried the native red squirrel will become extinct.

By Holly Giles | Deputy Editor 

Throughout lockdown people have fallen in love with walking and exploring their local area, with a UK survey showing 61% of women and 50% of men have been walking more often than before the pandemic. 15% of people have also been running more than before. On these trips into local woodlands and parks it is common to see grey squirrels, and occasionally red squirrels, but few know their complicated history with our country.

Grey squirrels were introduced to the UK from North America in the 19th century. These were often brought back from America as pets and rarities and then released into the wild when they were no longer wanted. The number of squirrels being released allowed them to establish a wild population meaning they could breed and increase in number in the countryside. Their population continued to increase from area of release and by the 1960s, according to one report, it was easier to say where grey squirrels were not found on a map than where they were. This fact is still true today.

Contrastingly the red squirrel is native to the UK but has been decreasing in number since the introduction of the grey squirrel. There is debate about if this is through direct competition for resources or if the species were declining anyway, but there are now an estimated 66 grey squirrels for every red squirrel in the UK. The success of the grey squirrel is thought to be because they are more successful in competing for food and because they have larger litters, meaning they can increase more rapidly. Grey squirrels eat green acorns which means the ripe acorns are not left for the red squirrels to be able to eat. Additionally grey squirrels are carriers of squirrel pox virus which, although it does not harm the grey squirrel, can lead to a serious infection in red squirrels, decreasing their numbers further. 

The dominance of grey squirrels is now out of control with the red squirrel being classed as Near Threatened in England, Wales and Northern Ireland. There are now growing projects of red squirrel conservation that aim to deter grey squirrels and encourage red squirrels to reproduce. As well as decreasing grey squirrel numbers for the red squirrel’s benefit, it is also important to reduce their number as a result of the damage they inflict to the countryside. 

In light of this, the UK government has given its support to a project to use oral contraceptives to control grey squirrel populations. The support stems from Environmental Minister Lord Goldsmith saying the damage the squirrels and other invasive species cause to UK’s woodlands costs the UK £1.8 billion each year. Goldsmith explains the damage from squirrels also threatens the effectiveness of effort to tackle climate change by planting trees. 

The question for many hearing this news is the practicalities of how this will be implemented. This is suggested to be done through feeding boxes for squirrels containing hazelnut spread containing an oral contraceptive. 

The work is part of a 5 year project by the UK Squirrel Accord (UKSA). UKSA explained:

“The Animal Plant Health Agency (APHA) is currently trialling three different methods of reducing fertility and creating an effective product that can be taken orally. The best of those being tested will be taken forward for further development in years four and five”. 

In order to ensure the safety of red squirrels from the medication the team are using a hopper feeding box that is species specific. They added: “Tests on a hopper to deliver the oral contraceptive to grey squirrels only are going well. The test bait, without contraceptives, is attractive to grey squirrels and the hopper currently prevents almost all but the very largest red squirrels from accessing it”.

So whilst it may sound like stuff of fancy, spiking hazelnut spread with oral contraceptives is both a reality and a necessity for the protection of our woodlands and our native red squirrels.


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