Return of the reds

In a long and often disappointing story for UK conservation, finally some good news. In the north of England, the red is on the rise.

With the help of grassroots conservation, spearheaded by Red Squirrels Northern England, a species that some believe should be our national mascot is returning to areas where it hasn’t been seen for years.

Grey gardens

The red squirrel’s demise has been caused by the deliberate introduction of the grey (or eastern grey) squirrel. Native to north-east America, the grey was considered to be a fashionable addition to private estates in England, and widely introduced to the UK during the late nineteenth and early twentieth century.

Starting in 1876, with the release of a singe pair on an estate in Cheshire, by the 1930s the grey squirrel population had exploded. A bounty for culled squirrels was established in the 1950s, but by then it was too late to halt the invasion. It’s now estimated that there are at least 2.5 million grey squirrels living in our gardens, parks and woodlands.

Source: BBC News

Source: BBC News

Red peril

Red squirrels are fussy eaters – greys are not. Unlike reds, they tolerate tannins, munching on tannin rich unripened acorns, which are a high-energy food source. This means that although red squirrels can eat ripened acorns, by the time they get to the dinner table, there are no acorns left to eat.

Unfortunately, acorns are one of the main food sources used by reds to build up their winter fat reserves. As a consequence, over time, direct competition with greys results in the gradual starvation of reds, a loss of physical condition, and the reduced ability to reproduce. Through direct competition alone, greys can replace reds within approximately 15 years.

Grey squirrels are also larger, and able to store up to four times more fat that than reds, meaning they are more likely to survive a harsh UK winter. They also produce more young, and can live at higher densities than reds (up to 15 individuals per hectare, compared to 2-3 per hectare for reds).

On top of this, grey squirrels carry the squirrel pox virus, and although they aren’t particularly affected by it, reds have no immunity. When passed on, a red squirrel will die within weeks. Studies suggest that the squirrel pox virus results in red squirrel population decline that is up to 25 times more rapid than through competition with grey squirrels alone.

Effects of the squirrel pox virus. Source: Red Squirrels in South Scotland

Effects of the squirrel pox virus. Source: Red Squirrels in South Scotland

Unfortunately the virus is now widespread across England. In Cumbria it is believed that up to 75% of greys have the disease. It’s now also spreading into Scotland, which until recently has been pox free, and a key stronghold for red squirrels. This map shows the distribution of grey squirrels with the virus in southern Scotland.

As a consequence of all this, from a population estimated at 3.5 million prior to the introduction of grey squirrels, there are now only approximately 138,000 red squirrels left in the UK. The majority are found in Scotland, with only about 15,000 left in England and 3000 in Wales.

Community conservation

In a good example of landscape scale, community conservation, Red Squirrels Northern England are culling grey squirrels, and monitoring approximately 300 woodlands, employing a team of rangers, an army of volunteers (over 1000 of them), and the buy-in of landowners with woodlands supporting red squirrels.

Culling involves catching and shooting greys using baited traps, whilst monitoring incorporates standardised techniques including observational surveys and camera trapping. This video provides a short summary of the work being undertaken by Red Squirrels Northern England.

Their efforts have been successful. A 2013 study indicates that in cull areas, red squirrel numbers rose by 7% from the previous year. This is the first recorded population increase of red squirrels in over 100 years. The study also indicates that grey squirrel numbers decreased by 18%.

Similar stories are being reported in other areas of the UK. Greys have been eradicated from Anglesey, viable populations of red squirrels have been established on offshore islands, and real progress has also been made in southern Scotland.

The future

Work is being undertaken to develop a vaccine, administered in food, to inoculate red squirrels against the squirrel pox virus. Perhaps this would be a more palatable outcome than widespread culling, which has received some criticism from animal welfare groups.

However, it will be several years before the vaccine is ready for testing. Until then, if we want to protect the few remaining red squirrels in the UK, it doesn’t look like we have many other options.

You can donate to Red Squirrels Northern England here. Should you wish volunteer your time, the Northern Red Squirrels website provides a database of local volunteer groups across the UK. Failing that, spread the word – because the red squirrel needs your help.

About Tom Evans

Tom is a Conservation Scientist with a background in Environmental Impact Assessment (EIA). He holds an MSc in Conservation Science from Imperial College London, and is currently undertaking a PhD at University College London (UCL), funded by the Natural Environment Research Council (NERC). His research focuses on the identification and management of impacts associated with invasive alien species. All views expressed are his own, and do not represent the views of UCL or NERC.
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