So what was the mysterious beast shown in the photo? As usual, the Tet Zoo readership proved too clever to be fooled by such a rubbish trick. That white blurry streak in yesterday’s photo was…
…. not a fox, lynx, marten, white carrier bag, draft excluder, house cat, tree trout, rhinogradentian, dormouse, slug, ent, iguana, arboreal monitor lizard, tree octopus, kitten, raccoon, tree-eel, kite skeleton, nor, sadly, a late-surviving, modern-day, dwarf arboreal gorgonopsian (wow – an impressive list of in-jokes there). It is nothing more than, as some of you correctly guessed, a lowly Grey squirrel Sciurus carolinensis, but an albino one. I saw it from the bus, and leapt off and gave chase. The little bugger evaded me and vanished. Later that same day, Richard Hing and I went in quest of it: it was still hanging around at the same place (this all happened in Portsmouth’s Victoria Park), but despite my best efforts I was unable to get a good photo. And, hey, the photo was taken with my mobile phone, so I wasn’t exactly working with the best equipment. Given that the photo is so awful, I thought identification of the object of interest might prove a challenge. Well done Douglas Gogerty, Epicanis, Paul Barrett, Nick and everyone else who correctly identified it.
Albino Grey squirrels aren’t really a big deal – they’re routinely reported in British urban populations, particularly those in southern England (Kent, Surrey and Sussex in particular), and people have been seeing them in and around Victoria Park for ages. There are also various places in the country with high proportions of melanistic Grey squirrels (Muirhead 1998): Hertfordshire is most strongly associated with melanism in the species, mostly because 12 melanistic individuals were introduced to Woburn [adjacent photo taken by Lindsay Abbas].
As, I suppose, everyone knows, the Grey squirrel is a native of south-eastern Canada and eastern USA, but as early as the 1820s it was being introduced to Britain. The first reported British sighting is from Denbighshire in Wales and dates to 1828 – there are other Welsh records that are said to predate 1830, but the details are vague (Lever 1977). The problem is that no-one knows who introduced these squirrels, or where they came from. And no, I don’t think there’s a good case to make that this North American endemic might have been an overlooked Welsh native. Documented introductions first occurred in Cheshire in 1876, and by the early 1900s people were introducing them all over the place. Virtually all of these squirrels came from North America of course, but we know of one individual (a female released in Buckinghamshire in 1909) who came from the South African colony: these had been introduced to Groote Schuur by Cecil Rhodes in about 1880. Despite a setback that occurred during the 1920s and another that happened in 1932, Grey squirrels increased their range between 1930 and 1945 and today they’re essentially ubiquitous, absent only from some islands (including the Isle of Wight), the Scottish highlands, and much of Ireland (Gurnell 1987, Matthews 1989) [accompanying range map borrowed from here: the forest research grey squirrel management site].
Grey squirrels are mostly a bad thing here in Britain. Some people (Bill Oddie among them) argue that they get a lot of people interested in wildlife, as they’re among our most familiar, personable mammals. But they’re a significant menace to forestry (they strip bark and kill saplings) and have been recently shown to have a major negative impact on passerines: believe it or don’t, they routinely eat passerine chicks, and might be one of the most important factors in passerine decline.
It is widely alleged that the spread of the Grey squirrel has resulted in the decline of Britain’s only native squirrel, the smaller, tufted-eared Red squirrel S. vulgaris [shown in adjacent image: from here]. This is a complex issue and even now it is argued as to what has really resulted in red squirrel decline. Grey squirrels do not hunt down and kill reds, nor are greys necessarily any better at adapting to life in urban places, as the Regent’s Park red squirrels in London seem to be doing fine, despite living alongside greys (Gurnell 1987), nor are reds doing badly because they’re limited to coniferous woodlands (they are equally at home among broadleaved trees). However, it does indeed seem that greys can replace reds: an established population of greys will lower the recruitment rate of juvenile reds into the population (Wauters et al. 2000). Greys also act as a vector for the transmission of the parapox virus: this kills red squirrels and can extirpate whole populations, yet greys typically show high sero-prevalance for antibodies to the virus and don’t die from it (Shuttleworth 2003).
Entirely by coincidence, Erik Meijaard – yes, the Erik Meijaard – added a comment about squirrels to Tet Zoo ver 1 on Friday (go here). And one last thing – if you like squirrels this youtube video is mandatory viewing (warning: it includes a few swear words).
Back to normal business soon enough; sorry for yet another distraction.
Refs – –
Gurnell, J. 1987. The Natural History of Squirrels. Christopher Helm, London.
Lever, C. 1977. The Naturalized Animals of the British Isles. Hutchinson & Co, London.
Matthews, L. H. 1989. British Mammals. Bloomsbury Books, London.
Muirhead, R. 1998. Black squirrels in Britain. British Wildlife 10 (2), 102.
Shuttleworth, C. 2003. A tough nut to crack: red squirrel conservation in Wales. Biologist 50 (5), 231-235.
Wauters, L. A., Lurz, P. W. W. & Gurnell, J. 2000. Interspecific effects of grey squirrels (Sciurus carolinensis) on the space use and population demography of red squirrels (Sciurus vulgaris) in conifer plantations. Ecological Research 15, 271-284.