Polar Bears - Are they a key 'indicator' species?

[jridg]

Another article on the possible plight of the Polar Bear. This study is different from those I have seen in the past. Please post your opinions/comments.

BBC News Article on Polar Bears (http://news.bbc.co.uk/earth/hi/earth_news/newsid_8700000/8700472.stm)

[PatW]

I really would not have thought of the polar bear so much as an indicator species. I suppose it is how you use the term. In the field, plants often a much better indication of the type of communities. Here in FL for example, bald cypress is a good indicator of a swamp forest, pines of a sandy dry upland --- only to a point mind you and so on. You have nice easily seen nonmotile species that indicate the conditions for a certain kind of community.

Using an apex predator as an "indicator" is rather tough. Apex predators are awfully rare. They are also highly motile and have large ranges. Apex predators generally range over a number of communities. They need to eat so much that they can not really be tied to a single type of community. However, human intervention usually messes up apex predators early on so their presence is a decent indication. Think of it as diving and if you see large grouper... the reef is probably well protected because otherwise they would be fished out.

[Rhone Man]

I have always thought that the extent to which people will leap to defend an endangered species is directly related to how cute and fluffy they are - people are much more excited about saving dolphin (which are not threatended) by eating dolphin-friendly tuna, than they are about the tuna (which are critically threatened).

Extinction is a highly inexact science, but if you accept that the background rate of extinction is approximately 3 species per day (about the same rate as it has been for the last million years or so), it doesn't look hugely significant. If the day when Polar bears finally do drop into extinction was 3 weeks next Tuesday, does that mean some magical tipping point has been reached? Or is it just a really good chance to put lots of heart tugging pictures of dead baby polar bears in the media?

I know what I suspect.

[drbill]

I would think they were more of a keystone species than an indicator species, Jim. But of course I rarely see polar bears here in our SoCal kelp forests (and then only when I'm extremely narc'ed and mistake them for mermaids!).

Rhone Man: what is the basis for the extinction rate being the same over the past million years? It doesn't seem to jive with my understanding, but I don't have any facts to back that up.

[Rhone Man]

Sorry, perhaps I oversimplified. I think people do acknowledge that the rate of extinctions has gone up, but what I was trying to say was that the natural appearance and disappearance of species (the 'background extinction rate (http://en.wikipedia.org/wiki/Background_extinction_rate)') is sufficiently high that I don't think any one species can ever be called a key indicator.

And I am particularly suspicious of cute, fluffy creatures being designated as 'key'.

To wit: an article from today's BBC news (http://news.bbc.co.uk/earth/hi/earth_news/newsid_8702000/8702598.stm) about cute fluffy birds which they have now declared formally extinct - makes for a much more interesting story than would slugs, insects and other micro fauna disappearing from the eco system.

[jridg]

Whichever side you may fall out on with regard to global warming, the article points out that with less ice, there will be fewer bears. As we know, when the apex predators are removed, the balance is disturbed and things will change. How will this turn out long-term? I have no idea.

[drbill]

Agree on the cute fluffy things, Rhone Man. That's a problem with human nature. Here on Catalina people seem to care more for the introduced American bison (which were never found on the island) than the endemic island fox which came close to local extinction due to the introduction of canine distemper from pet dogs.