In my on-going attempt to improve myself I recently attended a lecture by Paul Eric Aspholm on brown bear tracking. This was a much more enjoyable and informative lecture than the last one attended and full of such interesting facts that I just had to share them!
Though the brown bear (Ursos arctos) is found throughout Eurasia and North America the talk focussed on those living in Scandinavia (Norway, Sweden, Finland) and Russia west of the Ural Mountains. In the first half of the 19th century Scandinavia implemented a cull with the intention of wiping bears out. This cull was halted in the 1930s and since then populations have rebounded. Much of the work by Mr Aspholm involved tracking bears to determine population size and movements across the region.
The focus of the talk was shit. Lots and lots of shit. Spring shit, which is mostly grass. Summer shit, which is mostly meat and bones (growing bears need calcium!) and autumn shit, which is mostly berries. The bears are so dextrous that they can pick and eat individual berries and can get through tens of kilos of blueberries in a day! Female bears are quite careful about where they defecate but the males are much more casual in their toilet habits, to the extent that they sometimes accidently walk in a previous bear’s deposit!
The shit is gathered by helpful hunters (who sometimes collect human shit by accident!) and is sequenced to obtain genetic information about the depositor which can be used to track individual bears. Other tracking methods involve collecting hair in hair traps (a line of barbed wire set in a square with a delicious – to bears – smelling lure in the middle) and collecting footprints in snow. This last method was the most innovative (to me, at least). Bears walking over snow will leave skin cells in their footprints. All the scientists have to do is collect a few footprints (around 5-7), melt the snow, get the cells and then sequence the DNA to get a complete genetic profile.
These methods enable researchers to track the habits of individual bears over many years and sometimes several countries. They have been able to show that the bear populations have rebounded well since the end of the cull, with around 8 females reproducing each year in Norway. The hope is to get that to around 15 females a year, still significantly lower than the estimated pre-cull population but a healthy size considering the amount of habitat currently available to them. Most surprisingly of all, the populations show no evidence of genetic bottlenecking or reduced even genetic diversity despite little movement between populations.
As a public service we were given some tips in case we ever come across a brown bear. The traditional advice is to sing. This is, surprisingly, true as it is a sound that only humans can really make. If you scream, you sound like a frightened animal and a perfect chance for a snack. If you shout, you sound like an aggressive animal looking for a fight and the bear is likely to oblige. We were advised not look into their eyes, and most importantly of all – don’t turn your back on it. This is apparently an invitation to play and bears play rough!!
It was an absolutely fascinating talk and I learned so much. Many thanks to Mr Aspholm for such an interesting lecture.
Author
Sarah Hearne: hearnes[at]tcd.ie
Photo credit
wikimedia commons
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