You may have noticed that we have huge numbers of grey squirrels around Summer Fields. The Grey Squirrel is an invasive, non-native species that is a threat to our native population of Red Squirrels that had been the only species of squirrel in the British Isles for tens of thousands of years. Grey Squirrels were introduced by the Victorians in the 1870s as an exotic addition to private parks and gardens. They threaten the Red Squirrels in two ways…
- They have more powerful digestive systems so they are able to eat a wider range of food thereby out-competing the Red Squirrel in every habitat that they share. Their physically larger size also means that they win any competitions for nesting sites within the habitat.
- Grey Squirrels carry a virus called squirrelpox which doesn’t cause them any symptoms but which leads to disease and death in the Red Squirrel. This speeds up the rate at which Grey Squirrels replace Red Squirrels in any new territory they invade.
There are organisations that stick up for the Grey Squirrel and you can read a different take on this topic here.
One of the reasons that squirrels are such successful mammals is that they are very good at finding and storing food. They are notorious for raiding garden feeders and stealing seeds intended for birds. Many years ago, people started trying to make their bird feeders inaccessible to squirrels by building obstacles. Some took this to extremes by assembling whole assault courses for the squirrels to overcome. This squirrels did with remarkable speed. The video below is from a BBC News report from 20 or so years ago (hence the grainy picture quality). It does not just show the squirrel’s gymnastic skill but also its ability to learn from earlier failed attempts how to overcome each puzzle. I am sure that there are lessons for us all here!
Questions…
- Suggests one way in which squirrels are typical mammals.
- What trophic level do squirrels occupy within a habitat?
- What technique might you use to estimate the population of squirrels in a large wood?
- Red Squirrels prefer coniferous forests to deciduous forests. To what phylum do (a) conifers and (b) deciduous trees belong?
5. Using the picture as supporting evidence, what might be the effect on two other organisms if we were to significantly reduce the population of squirrels?
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