New species of invasive non-native mammal discovered in Britain
A new species of non-native mammal for mainland Britain has been discovered in Sunderland in North-East England. In 2021 an unusual photo of a dead shrew was posted by Melissa Young on social media caught ecologist Ian Bond’s eye. Ian reached out to Melissa, pointing out that it looked rather like a White-toothed shrew.
Ian Bond explains ‘White-toothed Shrews look fairly distinctive with a head more closely resembling Finger Mouse or the Clangers than a normal shrew. The problem with that identification was that they have never occurred on the British mainland before!’
Following contact with Ian, Melissa kept the suspected shrew in her freezer so further tests could be undertaken. A subsequent DNA test, undertaken by Ecotype Genetics and Swift Ecology Ltd, confirmed it to be the Greater White Toothed Shrew. In Britain this mammal is only found on the Channel Islands of Guernsey and Alderney, although it is found on the other side of the Channel as far north as the Netherlands.
The Mammal Society’s Allan McDevitt comments ‘Given the rapid spread of the greater white-toothed shrew in Ireland, it is no surprise that it has eventually found its way to mainland Great Britain. This is a worrying development however as this invasive shrew is clearly associated with the local disappearance of the native pygmy shrew in Ireland. It is known to outcompete other species of shrews on other islands, so it is urgent that its distribution and potential impacts on other shrew species is quickly assessed.’
There is no indication of how the shrews arrived in Britain, let alone Melissa’s Garden. However, this is not the first time this has happened. In Ireland, Greater White Toothed Shrews started appearing in owl pellets back in 2007 with subsequent research showing it had been there for some time and was spreading rapidly. A further trawl back through Melissa’s posts show photos of White-toothed Shrews since at least 2015. This means this species could be quite widespread by now without anyone having noticed. Research is underway to find out just how far the shrew, nicknamed the Sunderland Shrew, may have arrived.
Melissa Young said “I’ve always kept my cats indoors to reduce their impact on wildlife, so I was really surprised when they regularly started catching shrews. Thankfully, most were able to escape without injury, but the opportunity to study those that didn’t make it has led to this invaluable discovery! The wildlife on your doorstep is simply amazing and I’m thankful to Ian for his observations and guidance which led to us taking a closer look at something most people wouldn’t look at twice.”
This discovery has shown just how important it is to submit records especially as mammals are some of the most under-recorded species in Britain. We encourage the public to submit any unusual shrew sightings with photos via Mammal Mapper (the Mammal Society’s app) or on iRecord.
Gavin Measures, Invasive Non-Native Species lead at Natural England said: “This is a fantastic example of how important it is to be vigilant for invasive species in our gardens, parks and green spaces. We greatly encourage everyone to take part in citizen science as it supports the vital work of Natural England to protect the environment. This non-native shrew has had a negative effect on the Irish ecosystem. Evidence of this species in the United Kingdom now requires further investigation to establish how widespread it is, and any possible impact on our small mammal community”.
1 November 2022
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