The Grey Squirrel; the problems of an invasive species
The Grey squirrel is today a common sight across the length and breadth of the country, and can be seen in parks, gardens and woodlands dawn 'til dusk. However these furry little creatures are not all they may seem, and for our native red squirrel populations, their presence in the UK has spelt disaster.
Class - Mammalia
Order - Rodentia
Family - Sciuridae
Species - S. carolinensis
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| An Eastern Grey Squirrel - (http://www.oxfordmail.co.uk/resources/images/4128738/) |
One of the defining features of the grey squirrel is its bushy grey tail, that is as long as the entire length of the squirrel's body, if not longer! These squirrels often sit upright on branches or on the ground with their busy tails arched over their back, and as their name suggests, the grey squirrel is indeed mostly grey, with some red-orange fur interweaved with grey around the face and over the shoulders. They are approx. 23-30cm in length, and their adult weight can vary between 400-600g. Grey squirrels, like all squirrel species, have four toes on their front two feet, and five on their hind feet. Squirrels can often be seen bounding across lawns or across woodland floors, and the bound stride can be anything between 1-3 feet apart! Grey squirrels are one of few mammal species able to descend a tree trunk head first, with the act of turning their hind paws backwards so that their claws can grip the bark, enabling them to do so.
Grey squirrels are scatter-hoarders, meaning they hoard food in many small caches that may be retrieved at a later date. Each squirrel can make up to 10,000 caches each season, and they can recover about 4000 of these, as they have a very well-developed spatial memory. Studies suggest that they use certain landmarks to distinguish a cache site, as well as smell. They will eat tree bark, buds, nuts, berries and even fungi. The act of pulling the bark away from tree trunks or branches is actually very damaging to certain trees, particularly beech trees and the sycamores I described in an earlier blog post.
Grey squirrels are scatter-hoarders, meaning they hoard food in many small caches that may be retrieved at a later date. Each squirrel can make up to 10,000 caches each season, and they can recover about 4000 of these, as they have a very well-developed spatial memory. Studies suggest that they use certain landmarks to distinguish a cache site, as well as smell. They will eat tree bark, buds, nuts, berries and even fungi. The act of pulling the bark away from tree trunks or branches is actually very damaging to certain trees, particularly beech trees and the sycamores I described in an earlier blog post.
These squirrels do build nests, however they are known as "dreys", which are often strategically built in the forks of tree trunks, from dried leaves and twigs. These squirrels breed once or twice a year, with the older more experienced females typically being able to breed twice. Grey squirrels have a gestation period of approximately 44 days, and the offspring will be weaned by 10 weeks of age.
Grey squirrels are notoriously curious, and their curiosity and cunning has earned them, in some cases, the reputation of being vermin. They are quite destructive individuals, with nesting squirrels in roof lofts of houses or sheds being a threat to electrical safety, as they will nibble through wires/cables. They will also raid bird feeders for food, particularly when their natural sources of food are scarce.
However, despite being a common sight in the UK, grey squirrels are not a native species to the British Isles. This species is actually native to the eastern states of North America. It is an introduced specimen in the UK, and has become an invasive species, especially given that it has caused the rapid and concerning decline of our native squirrel species; the red squirrel. It is estimated that there are over 5 million grey squirrels inhabiting the UK, with as few as 120,000-140,000 red squirrels thought to remain. Since its introduction to the UK beginning in the 1870's by land owners as fashionable additions to estates, grey squirrels have been blamed for the reduction in red squirrel numbers, as a result of the competition they pose for food sources and habitat, and the introduction of the "squirrel pox" disease. Grey squirrels are said to be carriers of the Parapoxvirus which is a major threat to the survival of the native red squirrels, of which have no immunity to the disease. It takes only one grey squirrel amongst a population of reds to introduce the virus and have devastating effects on their population.
Although the red squirrel population in England and Wales is struggling, there are still high numbers remaining in Scotland, and numbers are believed to be stabilising in the north-east as a result of conservation efforts. However these efforts are not necessarily positive for the grey squirrels, as it often involves culling. According to a report in the Telegraph, dating back to January 2015, landowners can apply for funding of up to £100 per hectare per year, for 5 years, from the UK government's forestry commission or the EU, to enable them to fund efforts to rid grey squirrels from their land. The money may be used to pay for whatever method of culling the landowner chooses, for example, it could be used to buy warfarin to poison them, or for buying traps or guns.
The culling of grey squirrels is not seen as the right thing to do by many, and as a result, bioethics comes into force here. However we must ask ourselves whether the red squirrel is worth saving, and if the answer is yes, then the grey squirrel population must be controlled, however I do not believe completely eradicated, and there are better ways to control a population than killing. So, even though grey squirrels may be cute and fluffy, they are not a native species to this country, and as a result, they have adversely affected the ecology of native wildlife. In order to protect and conserve native British wildlife, it is vital that these little creatures are kept at bay!
Grey squirrels are notoriously curious, and their curiosity and cunning has earned them, in some cases, the reputation of being vermin. They are quite destructive individuals, with nesting squirrels in roof lofts of houses or sheds being a threat to electrical safety, as they will nibble through wires/cables. They will also raid bird feeders for food, particularly when their natural sources of food are scarce.
However, despite being a common sight in the UK, grey squirrels are not a native species to the British Isles. This species is actually native to the eastern states of North America. It is an introduced specimen in the UK, and has become an invasive species, especially given that it has caused the rapid and concerning decline of our native squirrel species; the red squirrel. It is estimated that there are over 5 million grey squirrels inhabiting the UK, with as few as 120,000-140,000 red squirrels thought to remain. Since its introduction to the UK beginning in the 1870's by land owners as fashionable additions to estates, grey squirrels have been blamed for the reduction in red squirrel numbers, as a result of the competition they pose for food sources and habitat, and the introduction of the "squirrel pox" disease. Grey squirrels are said to be carriers of the Parapoxvirus which is a major threat to the survival of the native red squirrels, of which have no immunity to the disease. It takes only one grey squirrel amongst a population of reds to introduce the virus and have devastating effects on their population.
Although the red squirrel population in England and Wales is struggling, there are still high numbers remaining in Scotland, and numbers are believed to be stabilising in the north-east as a result of conservation efforts. However these efforts are not necessarily positive for the grey squirrels, as it often involves culling. According to a report in the Telegraph, dating back to January 2015, landowners can apply for funding of up to £100 per hectare per year, for 5 years, from the UK government's forestry commission or the EU, to enable them to fund efforts to rid grey squirrels from their land. The money may be used to pay for whatever method of culling the landowner chooses, for example, it could be used to buy warfarin to poison them, or for buying traps or guns.
The culling of grey squirrels is not seen as the right thing to do by many, and as a result, bioethics comes into force here. However we must ask ourselves whether the red squirrel is worth saving, and if the answer is yes, then the grey squirrel population must be controlled, however I do not believe completely eradicated, and there are better ways to control a population than killing. So, even though grey squirrels may be cute and fluffy, they are not a native species to this country, and as a result, they have adversely affected the ecology of native wildlife. In order to protect and conserve native British wildlife, it is vital that these little creatures are kept at bay!
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