Saturday, 25 February 2017

Spain 24: Red? Squirrel

Red Squirrel - Spanish form
Once upon a time the only tree dwelling squirrel to be found across most of Europe was the Eurasian Red Squirrel Sciurus vulgaris. With a global range from Spain across to the Pacific coast and north to Siberia, there are currently 23 subspecies defined by size and colour of coat. 

Sciurus vulgaris - global range
We came across several Red Squirrels in Spain and were rather taken aback to find that they were not, in fact, red. Instead they were almost black with a reddish belly. This is the standard appearance of the subspecies found in the north of Spain, alpinus. Two other subspecies have been identified in the Iberian peninsula, a large form in the south termed infuscatus, and a medium sized form with a black tail termed numantius which is found in the Systema Iberico. 

Red Squirrels are not always Red! - Urals subspecies in winter coat
In Britain the subspecies is an endemic form called leucurus, but there is an often overlooked problem with this form. During the medieval period there was widespread deforestation across much of England and Scotland and Red Squirrels became extinct over much of their range. With encouragement for forestry from the 18th Century onwards the possible habitat greatly expanded, and as part of the fashion for ornamenting land owners’ estates Red Squirrels of various European subspecies, mainly from Germany and Sweden were imported and released in both England and Scotland. As a result, there are probably very few true, pure blooded British Red Squirrels left, although the population in Cumbria seems to be relatively free from admixture.

British Red Squirrel
Eurasian Red Squirrels prefer conifers, but they can survive in deciduous woodland especially where there is hazel and a reasonable variety of food sources. Cones are stripped of their seeds, and in addition they will eat fungi, fruit, and occasional bird eggs and nestlings.  Vagaries in the seed crop can cause major fluctuations in numbers, and unfortunately they cannot compete successfully with Eastern Grey Squirrels, S. carolinensis, which has been introduced to Britain, and unfortunately also Italy. Eastern Grey Squirrels can eat acorns, which Red Squirrels avoid, and make more use of fallen nuts and other sources on the ground, while Red Squirrels spend more time in the canopy. Grey Squirrels are also vectors for the parapox virus to which they are immune but is lethal to Red Squirrels.
Eastern Grey Squirrel
Since pine cones and seeds are available all year round there is no need for Red Squirrels to hibernate, but in bad weather they spend long periods in their nests or dreys. A squirrel drey is a globular bundle of twigs in the fork of a tree and grass containing a nest chamber lined with moss. The squirrels use these for sleeping and shelter, and females use them to raise their young.
Reproduction in Red Squirrels begins in February and March with males chasing females. After mating a pregnancy of 38 days results in a litter of 3-4 young. They reach independence at 8-10 weeks. A female may then mate again in midsummer and produce another litter. Life span may be as much as 10 years in captivity, but maximum lifespan in the wild is nearer 3.
Pine Marten
Natural predators of Red Squirrels are mostly avian such as owls or Goshawks, but they are also prey when on the ground for Red Fox or Stoat. Pine Martens may chase them through the trees as well. In the UK, it appears that Pine Martens may actually benefit Red Squirrels, as the larger and more terrestrial Grey Squirrel is preferred, and as a result the competitive edge tilts against Greys in favour of Red Squirrel.

(images from Wikimedia)

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