Red and grey squirrels in Britain

This is an Eurasian red squirrel (Sciurus vulgaris) video from Germany.

By Peter Frost in Britain:

The battle of the squirrels

Friday 13th January 2017

PETER FROST’S affection for the native British red squirrel sends him in search of measures that would boost its survival chances

There were once three and a half million of our native red squirrels (Sciurus vulgaris) in the forests and woodlands of Britain.

Today that population is down to well under 150,000 and although still reducing dramatically a number of initiatives are reducing the rate of decline.

What happened? Well, in 1876 some stupid aristocrat decided to import grey squirrels (Scirius caroliniensis) from their native North America releasing them in Henbury Park, Cheshire.

It’s not clear why they were introduced, probably as a live novelty garden decoration. Rich Victorian landowners simply had no idea about the risks of introducing non-native species to their estates.

Other landowners in other parts of Britain also imported the greys which spread rapidly. There are now estimated to be about 2.5 million grey squirrels in Britain.

Unlike the bold and oft-seen greys our native red squirrels are very shy and elusive and spend much of their time in the tree canopy. Telltale signs to look for include large dreys in trees, scratch marks on bark and chewed pine cones that look like chewed apple cores. You might also hear the distinctive “chuk chuk” noise they make.

Although the grey squirrels don’t actually attack the native reds they carry the squirrel pox virus which is fatal to red squirrels without harming its grey carriers. Squirrels come in all colours.

Entirely black ones are becoming common and originate in colder regions of Canada where their dark skins absorb more winter sun to keep them warm.

A family of at least two dozen pure white squirrels have been hitting the headlines in Edinburgh. Both these black and white varieties are actually greys — if that makes sense.

Colours are very variable and some grey squirrels can have red fur down their backs and on their feet. Red squirrels usually have russet red fur, although coat colour can vary with some reds appearing very grey. Reds are smaller than the greys with ear tuffs — large tuffs in winter.

By being larger, more robust and able to eat a broader diet, grey squirrels compete more successfully for food and places to live with the reds. Greys cause immense damage to woodland by stripping the bark from trees in search of sweet sap which leads to the death of the tree. They are also devastating plunderers of birds’ eggs and chicks.

Now there is another threat to the red squirrel. Populations of reds on Brownsea Island in Poole Harbour and in parts of Scotland have been found to carry the leprosy bacteria. Although it is the same disease that can be passed to humans, experts believe this poses little real danger.

But there are already calls for the animals to be culled. There are still many places in Britain where you can see red squirrels — their introduction to Tresco in the Isles of Scilly in 2014 has been a huge success and they have become a tourist attraction.

Reds from Anglesey have crossed the Menai Strait and started breeding on the mainland and have been seen in gardens in Bangor. A new project — Painting the Town Red — aims to clear grey squirrels from the town so that red squirrels can recolonise Bangor’s parks and open spaces.

They build large nests, called dreys, often in the forks of tree trunks and are usually solitary, only coming together to mate. Related squirrels will share dreys to keep warm during cold winter months.

Reds range widely, especially when looking for mates. They produce young, called kittens, in the spring and can sometimes reproduce a second time in the summer if conditions are right.

Courtship displays high in the trees can be spectacular. Females usually have two or three kittens but litters can have up to six young. Females bring up the young and are very protective.

Up to half of kittens survive to adulthood. Young red squirrels are weaned off their mother’s milk after about two to three months, when they have developed a complete set of teeth.

They are mostly seed eaters and favour pine cones, but also eat larch and spruce. Their diet also includes fungi, shoots and fruits of shrubs and trees, and occasionally birds’ eggs.

They are picky eaters choosing between good and bad nuts by holding them in their paws in the characteristic nursery story pose.

Reds do not hibernate and store fungi in trees to eat over the winter months. They put on weight in the autumn when food is plentiful to help them through the winter. Females need to be fat and healthy so as to be in good condition for breeding.

The main threats to the survival of the reds are the increasing number of grey squirrels, the squirrel pox virus and, not least, road traffic.

The main predators of red squirrels are birds of prey such as goshawks and the pine marten now reestablishing itself in our more remote woodlands. In some urban areas domestic cats and irate bird table fans are also a threat when squirrels go into gardens to raid bird feeders.

Research published in the Journal of Animal Ecology reveals a new mechanism of how grey squirrels affect native red squirrels in Europe through parasite-mediated competition. An international team from universities in Italy and Belgium used a natural experiment of populations of native red squirrels (Sciurus vulgaris) co-inhabiting with alien grey squirrels (Sciurus carolinensis) to investigate the impact of a parasitic helminth (worm) transmitted by grey squirrels, Strongyloides robustus, on naive red squirrels’ personality: here.

5 thoughts on “Red and grey squirrels in Britain

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