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This is where I post various musings about wildlife and ecology, observations of interesting species (often invertebrates)
and bits of research that grab my attention. As well as blogging, I undertake professional ecological & wildlife surveys
covering invertebrates, plants, birds, reptiles, amphibians and some mammals, plus habitat assessment and management
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Wednesday, 22 December 2010

Reindeer in Britain: ecology, conservation and welfare outside their native range

Known as caribou in North America, reindeer (Rangifer tarandus) were once widespread in Europe reaching as far south as Spain, but are now mainly found in Norway and parts of Russia, in some cases being found wild alongside domesticated herds. Whilst their bones occur frequently in prehistoric middens, the last reliable record in Britain was approximately 8,300 years ago after which they disappeared (later records are uncertain), probably due to climate change, although hunting pressure may have also been a factor. However, 29 reindeer were reintroduced to Scotland by Swedish Laplander Mikel Utsi in the 1950s. Despite some climate-related difficulties such as troublesome insects, the herd generally thrived, although mortality rates are raised due to dog attacks and eating discarded litter. The herd is now managed at 130-150 animals across two areas - the Cairngorms and the Cromdale Hills – and are the only genuinely wild (if managed and visited) reindeer in Britain. There are other more-or-less free-ranging herds such as at the Trevarno Estate near Helston in Cornwall. These animals were introduced as a Christmas attraction in 2008 and have acclimatised to the warmer-than-Arctic weather, even producing the first calf in England for probably thousands of years in spring 2010.

Reindeer on short montane grassland.
The lack of fecundity is unsurprising given the challenge of the English climate (OK, it’s cold at the moment, but...) especially in the south-west. Reindeer are cold-adapted and fond of their Arctic diet of mushrooms, lichens and other vegetation with their associated minerals. Reindeer’s cold-adaptations include short legs, ears and tail, a hairy muzzle, broad flat hooves for walking on snow (winter) and boggy ground (summer), dense winter coats and particularly rich milk (more than 20% fat while human milk is 3.5% fat) to help the young survive and grow in cold conditions. They are also poorly adapted to the diseases and parasites found in the warmer areas of Britain, with reports of animals dying prematurely having been imported for festive grottos and parades (especially following relaxation of quarantine rules), and subsequently being exposed to diseases from British livestock, along with issues of poor diet and welfare, and the stress of transportation from large semi-wild herds.

Reindeer on grasslands below mountains.
Research by Hughes et al. (2008) on Canadian animals suggests that even in the Arctic, parasites may impact populations by worsening the effects of forage availability (which is seasonal and limited) on individuals’ condition, fecundity and survival. The study showed that, in females over 2 years old, by the end of winter there was a significant decrease in body weight with increased nematode burden, and a decrease in back fat depth with increased warble-fly (Hypoderma tarandi) abundance (which was also associated with reduced chance of being pregnant). Although not directly relevant to the British population, it is possible that muskox (Ovibos moschatus) share some parasite species with reindeer, leading to elevated burdens in the co-host. Thus, parasites may have contributed to a previous shift in winter range by reindeer herds, suggesting in effect a type of competition between the two species. If a similar effect were seen in Britain, reindeer would be unable to shift away from the effects of disease and parasites as most are in captivity (often with relatively inexperienced owners/handlers), while the wild Scottish herd is constrained within a limited area. Thus welfare and animal husbandry standards need to be high (at present, reindeer owners do not have to report unusual deaths to the Veterinary Laboratories Agency, so rigorous research and scrutiny is difficult) and it is important to understand the ecology of such an Arctic-adapted species when introduced into a warming temperate environment.

Lastly, predation; there may be none of the large 'typical' predators such as wolves in Britain (yet), but there is video evidence from Finland of golden eagles (Aquila chrysaetos) hunting reindeer calves - I've not heard of this happening in Britain, but with golden eagle numbers having increased in Scotland, I would be very interested to hear if this behaviour has been witnessed...

For general background information on reindeer, click here.

Bye for now - and season's greetings! Got any lichen...?

Reference
Hughes, J., Albon, S., Irvine, R., & Woodin, S. (2008). Is there a cost of parasites to caribou? Parasitology, 136 (02), 253-265 DOI: 10.1017/S0031182008005246

Picture credit
Thanks to ‘Animal Photos’ for making these images available via the Version 3.0 Attribution-ShareAlike Creative Commons License.


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