So here’s this article, “Rethinking extinction,” the main point of which is that things aren’t as bad as commonly stated. It’s written by Stewart Brand, who I understand is considered a “green modernist” or some other flavor of supposed environmentalist who takes a more “pragmatic” and corporate-friendly or high-tech-will-save-us approach to resolving environmental problems.
I don’t have the background to evaluate the majority of his data and know whether it’s true or whether it’s just carefully framed (but the generally unhappiness of the commenters suggests the rosy picture he’s painting might be a little -too- rosy), but some of the things he pointed out about the high rates of extinctions on islands struck me.
Many new species readily emerge on ocean islands because of the isolation, but there are few other species to co-evolve with and thus they have no defence against invasive competitors and predators. The threat can be total. An endemic species under attack has nowhere to escape to. The island conservationist Josh Donlan estimates that islands, which are just 3 per cent of the Earth’s surface, have been the site of 95 per cent of all bird extinctions since 1600, 90 per cent of reptile extinctions, and 60 per cent of mammal extinctions. Those are horrifying numbers, but the losses are extremely local. They have no effect on the biodiversity and ecological health of the continents and oceans that make up 97 per cent of the Earth.
The frightening extinction statistics that we hear are largely an island story, and largely a story of the past, because most island species that were especially vulnerable to extinction are already gone.
The island ecosystems have not collapsed in their absence. Life becomes different, and it carries on. . .
What he does NOT go on to mention, anywhere, is that there is more than one kind of island population.
When I was looking through the IUCN’s Red List for extinct species last year, in the invertebrate section, I found so many snails. So many! For the species for which there was much information, there seemed to be a common theme: they were known to only one place. They’re snails – they can’t fly, they don’t move fast, they don’t range over 100s or 1000s of acres. Ditto some aquatic insects. And I saw a similar thing with a number of species of extinct fish: they were residents of one stream or river or lake. Deer can travel great distances. Many birds do as well. Freshwater fish have some limitations.
In my reading, sometimes I find a story about a conflict between a developer and some local conservation agency, because the developer wants to build a hotel or whatever on this plot of land where the only known species of some rare plant, or frog, lives.
If you’re a small animal – or a plant, or a fungus – you don’t need the land you live on to be surrounded by 1,000s of miles of water for your home to effectively be an island, and for the threat of a new, highly competitive species (i.e., invasive, especially a new predator), or habitat destruction, to be as bad for you as what happened to the birds of Mauritius Island.
I also think it is misleading for Brand to complain about how the IUCN lists certain populations of a species as at risk of extinction, when their total global population is not. Cod, all together, may not be in the same level of danger of extinction as cod off the eastern seaboard of the United States – but that doesn’t mean the danger that particular population IS in isn’t a worry. If the local population is only 3% of what it was 200 years ago, I think that’s a problem for the entire ecosystem. Similarly, judging the health of the salmon population by looking at ALL salmon of one species is a far different thing than the salmon from one particular river – there may be chinook in multiple watersheds, but each stream develops its own unique population that is adapted to the unique features of that stream (when does it flood, does it end in an estuary, etc.). Trying to boost the population by bringing in hatchery fish who aren’t native to that stream is not going to lead to success the way that helping the native salmon recover, even if technically they are the same species.
I do hope he’s right, that we really aren’t well on our way to a 6th Great Extinction, but I’m not sure he’s presenting things in the most objective manner.