The Red Squirrel Sciurus vulgaris is the only species of squirrel native to the UK and Western Europe. It is about half the size of its congener, the Grey Squirrel Sciurus carolinensis, with mean head and body length 220 mm, mean tail length 180 mm and weight ranging from 239-435 g (male) and 220-355 g (female). The upper fur is uniformly dark but variable in colour, according to the season, from red brown or bright chestnut to deep brown or grey brown. This difference is partly attributed to the introduction of Red Squirrels of European origin, which have interbred with the native light-coloured race, S. vulgaris leucocorus (Hale and Lurz, 2003). The squirrel’s underside is white. Immature Red Squirrels are often redder than adults (Barrett-Hamilton and Hinton, 1910-1921). Body fur moults twice a year, in spring and autumn, with the hairs being longer in winter than in summer. The bushy tail is dark brown in the autumn and bleaches over the summer, moulting only once a year in the autumn. A characteristic feature of a Red Squirrel in winter pelage is the long dark ear tufts, which thin or disappear during the spring and summer. The total British population estimate is 161,000 (Harris and Yalden, 2008).
The Red Squirrel is diurnal, does not hibernate, swims well should the need arise, has two litters per year, produces up to six kittens per litter (average three) and can live up to six or seven years in the wild (mean three years; up to 10 years in captivity). Red Squirrels spend an average of 70% of their foraging time in trees. The population density is 0.5-1.5/ha for both deciduous and coniferous forest.
Fossil records indicate that the first recognizable tree squirrel (Protosciurus) probably evolved about 34 million years ago and the first tree squirrel in Britain, White’s Squirrel Sciurus whitei, evolved during the Pleistocene in the Cromerian period, 780,000 to 450,000 years ago (Holm, 1987; Harris and Yalden, 2008). White’s Squirrel seems to have been the ancestor of the Red Squirrel: it was present in the coniferous woodland which covered Britain at that time but appears to have died out during the Ice Ages. S. vulgaris appeared at the end of the last Ice Age, 7,000-10,000 years ago (Holm, 1987). The earliest British fossil record dates from the Mesolithic period, 8,710 BP (Harris and Yalden, 2008).
Records of the existence of Red Squirrels in northern England begin in the 1st century AD, with museum specimens of squirrel carvings (Shorten, 1962). The squirrel is part of the coats-of-arms of some northern county families, and is on the 8th century Bewcastle Cross. Its skin “was known in commerce in Berwick in 1377; the skins however may have been imported” (Barrett-Hamilton and Hinton, 1910-1921). Red Squirrel populations have fluctuated throughout the centuries through disease or bad weather. During the 15th and 16th centuries the national need for timber as fuel for industry, agriculture and war resulted in extensive deforestation and neglect of woodlands. This, plus a series of bad winters, resulted in rapid declines in squirrel populations, almost to the point of extinction in some areas. Then, during the 19th century, large forests were planted to replace those ancient woodlands and there were various Red Squirrel re-introductions. So, with plenty of suitable habitat, Red Squirrels multiplied again until they reached “peak numbers” (Holm, 1987). Barrett-Hamilton and Hinton (1910-1921) state that they “were common in all woodland localities of Great Britain, except only those in which numbers are kept in check by persecution”. In 1889, 2,281 Red Squirrels were shot as timber pests by the Commissioners of the New Forest, and in 1903 the Highland Squirrel Club proudly announced the destruction of 82,000 Red Squirrels in the first 30 years of the club’s existence (Holm, 1987).
Red Squirrel distribution in the North East may reflect the national pattern. In 1864 Mennell and Perkins wrote about squirrels in Northumberland: “Red Squirrels are abundant in many parts of our district, especially about Riding Mill, Hexham and Shotley Bridge, and in the woods north of Morpeth, but are not by any means universally distributed.” They cite the Reverend Bigge who wrote: “the red squirrel appeared a few years ago at Matfen, Cheeseburn Grange and Dissington,” suggesting that they were extending their range at this time. Records in the regional database for 1879 confirm their presence at two of these Northumberland sites. In County Durham, a Mr Hutchinson (cited by Mennell and Perkins, 1864) wrote in 1840: “Squirrels some few years ago were not known in this County. They were first introduced by Salvin of Burn Hall, and have increased and extended to most of the wooded parts.” By 1864 Mennell and Perkins found them “common in some areas of Durham County, for example, St John’s, Weardale, but not others”. The first Red Squirrel record on the regional database for County Durham was near Stanhope in 1879. From various reports around 1900 Temperley (1953) suggests that the squirrels’ local distribution actually fluctuated, but that they were “normally present at Gibside and in Chopwell woods” at that time.
As the Grey Squirrel began to establish itself in Britain around the turn of the last century (see Grey Squirrel account) some naturalists quickly became aware of the potential threat to the Red Squirrel: “… should it (the grey squirrel) gain a good footing here, as seems not unlikely, it will prove most probably to be a most formidable rival for our native species to face” (Barrett-Hamilton and Hinton, 1910-1921).
In 1953 Temperley conducted the first co-ordinated Red/Grey Squirrel survey across Northumberland and Durham. Red Squirrel presence was confirmed in all the woodland areas surveyed in Northumberland. They were also in many gardens and houses where they apparently came indoors regularly for food and were often kept as pets (Pitt, 1946).
However, in County Durham Temperley’s surveyors found them “generally scarcer than they had been in earlier years”, having “declined of late years”, and said that “The best populations were to be seen in the Forestry Commission plantations at Hamsterley and Bedburn.” Some people attributed this loss to the bad winter of 1946/47, but others disagreed. One surveyor was quoted as saying “I have also seen specimens with skin trouble similar to mange in foxes, but not often.”From the 1960s onwards, the regional database gives an interesting insight into Red Squirrel distributions (and probably observer effort, as awareness began to be raised). In the 1960s, records were few and far between (17 records overall) but Red Squirrels were to be found in areas with suitable habitat across Northumberland and most of Durham except the southeast. Through the 1970s and 1980s numbers of recorded sightings increased (106 and 240 respectively), with many more records coming in from the west of County Durham than the east.
Research into the decline had been sporadically ongoing since Middleton’s ground-breaking paper in 1930. From the early 1980s onwards it began to intensify. A comprehensive summary can be obtained by referring to Harris and Yalden (2008) and it is now well established that the presence of the Grey Squirrel is instrumental in the decline of the Red Squirrel.Grey Squirrels displace reds in two ways: by the transmission of squirrelpox virus (SQPV), to which they are immune, but which is fatal to reds (for further information see, for example, Bruemmer, 2010), and through interspecific competition for food and habitat which reduces female fecundity and juvenile recruitment (Wauters et al, 2002; and for review see Harris and Yalden, 2008).
A distribution map for Red Squirrels in Yorkshire, (Tonkin, 1985) showed that there had been no records of Red Squirrels in the area just south of the Tees since 1955. Arnold’s distribution atlas of 1993 shows that they may not have been there since 1959. County Durham’s ecologists were also noticing a loss of Red Squirrel populations, especially in the south of the county. In Cleveland, north of the Tees, the species was reported in the woodland complexes of Wynyard up to the early 1980s (John Pickard, pers. comm. to Ian Bond, 2001). It hung on much longer in the Thorpe Bulmer Dene complex between Hartlepool and Easington where the last report was in November 2005. The previous year the gamekeeper covering those woodland areas claimed to have culled 120 Grey Squirrels and blood tests on some of those proved that they carried SQPV (Ian Bond, pers. comm., 2012). Red Squirrels seem to have also disappeared from east Durham at around this time, with the last sighting in Castle Eden Dene in August 2004 (ERIC database, 2012). The database also records that a poxed corpse from Peterlee was sent for post mortem in June 2005. When Grey Squirrels arrived in Northumberland (first ERIC record is 1989 in Hexham) the decision was taken to try to save its population of Red Squirrels. Conservation strategies were initiated: The Red Alert North East programme was set up in 1991 (founded by Lord Ridley) and immediately conducted the first Red Squirrel survey, using records from the public which resulted in more than 1,200 records in the first year. Co-ordinating with Red Alert North West (1993) and the “Red Squirrels in South Scotland” project (1994), the Wildlife Trusts continued to use this initiative to promote public awareness by talks, surveys, habitat management and liaising with landowners (Stewart, 1997). In support of this, local governments wrote Biodiversity Action Plans for Red Squirrel conservation.
Further strategies were initiated, using the latest research undertaken by Peter Lurz at Newcastle University and John Gurnell at the University of London. This resulted in 16 key Red Squirrel reserves being identified across Northumberland to be managed for Red Squirrels (later increased to 17). The “Save Our Squirrels Project” which ran from 2006-2011, funded by the Heritage Lottery Fund, carried out habitat management and squirrel conservation activities with landowners and managers in the reserves and surrounding areas. Volunteer Red Squirrel conservation groups were established, under the umbrella of Northern Red Squirrels. In April 2009 the conservation effort went national with the formation of the Red Squirrel Survival Trust (RSST), under the patronage of HRH Prince of Wales. The RSST launched Red Squirrels Northern England (RSNE) in February 2011. It is a partnership project between RSST, Natural England, the Forestry Commission and the Wildlife Trusts and is the largest, most ambitious Red Squirrel conservation project yet launched. RSNE aims to safeguard and extend Red Squirrel populations and limit the impact of Grey Squirrels on Red Squirrel populations in northern England. Two hundred and seventy tetrads across Northumberland, from Slaley and the Derwent Valley northwards, have been identified and 80 woodlands are being monitored bi-annually. Employed staff are carrying out Grey Squirrel control by trapping. The objective is to confirm that, with sufficient effort, it is possible to retain a Red Squirrel population if Grey Squirrels are consistently removed (Nick Mason, pers. comm., 2012). The results of the first RSNE monitoring survey are shown in Figure 1 (over page).
In 2012 Red Squirrel distribution north of the River Tyne is still widespread in suitable habitat. In County Durham and Teesside the species is extinct except for populations at St John’s Weardale, where a Red Squirrel was photographed in November 2011; Pow Hill, where a Red Squirrel was unfortunately shot in August 2012 (T. Coult, pers. comm., 2012); the National Trust estate at Gibside, latest sighting 14 April 2012; and Ruffside, with probable small populations remaining at Killhope and Harbour House (T. Coult and H. McDonald, pers. comm., May 2012). The Red Squirrel is protected by the Wildlife and Countryside Act (1981) Schedule 5 and 6 (as amended). For details of legislative protection, a summary of UK BAP status and recommended actions, survey methodology and impact assessment see Gurnell and Lurz (2012).
Written by Veronica Carnell (November 2012)
Statistical analysis of monitoring results gathered from 2012 to 2014 suggests that Red Squirrel range remained stable for this period. It will be the first time that we have been able to say with confidence that Red Squirrel range is not in terminal decline. A reduction in Red Squirrel detection occurred during 2015 but should not distract from this positive message, as fluctuations in populations are normal. It is difficult to definitively assign one factor, as environmental stochasticity may be due to a combination of response to: weather, disease, competition, predation, or other factors external to the population.
Grey Squirrel numbers and distribution, for example, were generally down following a harsh winter in 2012/13, coinciding with a paucity of natural food supplies. It would appear that Red Squirrels did not fair so poorly during the harsh winters. The following two years (2014/15) experienced milder winters, coinciding with abundant natural food supplies, in particular with hazel and beech mast. Grey Squirrels naturally thrive under such conditions; their ability to outcompete Red Squirrels in broadleaved woodlands being well documented.
Interestingly, Red Squirrel stronghold and wider landscape survey results indicate that, proportionally, Red Squirrels occupy more survey sites within strongholds than within the wider landscape. In contrast, Grey Squirrels occupy more survey sites within the wider landscape, than in the strongholds. This is likely to be due to the combination of the historical Grey Squirrel control regime in strongholds and the tree species composition in strongholds (> conifers = small seeded tree species), which dissuade Grey Squirrels from thriving there. It should be noted that detection probability is likely to correlate broadly with population density, so non-detection implies either low density or absence.
The message is that fluctuations in wild animal populations, linked to environmental factors, are entirely natural and that Red Squirrel range seems to have stabilised. We should celebrate the achievement of the monitoring programme in documenting these results and encourage all those involved in active Red Squirrel conservation to continue their hard work.
Written by Heinz Traut (last updated April 2016)