Evolution 101: Darwin’s finches
You couldn’t really pick a less likely pinup if you tried, but Darwin’s finches are undeniably the face of evolution. Six inches high, and drab in the extreme, they don’t make quite as good a first impression as – say – a blue-footed booby or a giant tortoise. But, for a change, this poster boy isn’t all about looks...
Why all the fuss?
Darwin’s finches are textbook examples of genetic mutation. All 13 species descended from a single ancestor which came to the islands from mainland South America, each developing unique characteristics which make them ideally suited to eating very specific foods.
The biggest differences between the species lie in their beaks.
- The three ‘tree finches’ and the warbler finch have needle-like beaks which are great for skewering insects.
- The four ‘ground finches’ have blunt, short beaks for crushing seeds.
- The vegetarian finch and the two ‘cactus finches’ have long beaks which have evolved specifically for tearing at the flesh of cacti.
You might have noticed that only 11 finches are described above. There other two include the ingenious woodpecker finch which holds thorns in its beak and uses them as tools to get insects out of their lairs. Nifty.
Why Darwin’s finches?
Darwin had nothing to do with the finches’ nickname, and to be honest they shouldn’t really be called Darwin’s finches at all. They were not even mentioned in The Origin of Species, although Darwin did write the following about them in his journal: “One might really fancy that one species had been taken and modified for different ends.” Precisely.
The name ‘Darwin’s finches’ was first used by Percy Lowe over 50 years after Darwin’s death. Darwin didn’t even even collect any of the finches during his famous visit to the islands, but fortunately some of the other people on the voyage did.
When Darwin got back to Britain, the ornithologist John Gould informed Darwin that he was dealing with entirely separate species as opposed to ‘variations’. If anything, they should be called Gould’s finches.
Will I see them?
If you book a Galapagos Cruise with SA expeditions you’ll definitely run into at least some of Darwin’s finches. In fact, some species may even eat out of your hands. You can’t help but see the small ground finch, the warbler finch and the small tree finch, but if you’re an avid twitcher you should be able to identify many more species. Bring a decent bird book and a pair of binoculars.