Saving the mangrove finch:
As a young man Charles Darwin was invited along on a voyage on a ship called the Beagle. The invitation was apparently so he could keep the captain cheered up, but he improved the time by making observations in nature that later contributed to his acclaimed book Origin of Species, actually mostly a charming account of pigeon husbandry. Among Darwin’s observations was the fact that in the Galapagos islands there are finches that occupy the ecological niches of various non finch species. Evidently some finches got there before other birds and spread out and diversified.
These celebrated species are now threatened with extinction. (Saving an evolutionary icon SCIENCE vol. 329 no. 5987 July 2, 2010 page 17) In fact all have already gone extinct except for the mangrove finch, which is down to about 100 birds. The birds survive in an area that is afflicted with rats that eat the birds’ eggs. The rescue plan is to take six of them to a less rat infested area. They regard this as a desperate gamble.
I have high hopes. Previous attempts at saving endangered species have, like the current plan for the Coho salmon, consisted of trying to maximize the genetic diversity of the population. The jury is still out, but it sounds to me like a recipe for disaster. When an attempt was made long ago to rescue the passenger pigeon, the reasoning was that since they often gathered in enormous flocks for migration, that they must prefer that all the time, and all the ones that could be found were put in a single enormous cage. They went extinct.
Six strikes me as a good number. Unless the birds have been chosen from the greatest possible distance apart, all that remains is for the workers to keep their hands off a job well done and let nature take its course. We should see a lot of birds in a few years.
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