When Charles Darwin comes up in conversation (it does happen, I promise), mention of the Galapagos Islands is sure to follow. The Galapagos have been described as a world within themselves. The islands are home to unique species like giant tortoises, equatorial penguins, and swimming iguanas. Darwin’s finches are also famous residents of the islands.
Darwin visited the Galapagos for five weeks in 1835 as he worked as a ship’s naturalist aboard the HMS Beagle. While exploring the islands, he collected a variety of plants and animals to study in greater detail later on. Upon his return home to England, he passed his feathered collection along to the renowned ornithologist John Gould for further examination. Gould categorized the finches he received into 13 species. All of the finches were remarkably similar in morphology except for their beaks.
Darwin was dumbfounded by Gould’s findings. Could it be that the 13 species had evolved from a single ancestral finch? The answer is yes, and the finches helped serve as a springboard to Darwin’s scientific breakthrough – nature selects for characteristics that make organisms better adapted to their environment, changing populations over time.
The beak is an avian necessity for handling and manipulating food. For anyone that’s ever put out birdfeeders for a little backyard birding, you know that different seeds attract different birds. Goldfinches love thistle, hummingbirds love nectar, and jays love peanuts. Sunflower seeds, an all-purpose food, are attractive to a variety of species.
When you live on islands that are geologically young like the Galapagos, there isn’t a wide variety of food available. Darwin described the islands as “a scattering of rocks with the scrubbiest of vegetation”. A finch that lives on the islands and eats the same food as all of the other finches faces fierce competition. Competition is a lose-lose situation. Character displacement, evolutionary changes in species to minimize competition, may best be seen in the beaks of Darwin’s finches.
Among the 13 species of finches on the Galapagos, you can see cactus finches, a vegetarian finch, ground finches, tree finches, and even a woodpecker finch. Just by reading the list of names, you get an idea of their food preferences, all of which are slightly different. Less competition often leads to greater reproductive success, the goal of survival.
If you make it to the Galapagos and come across some of Darwin’s finches, pause for a moment. You just might see the beak of the finch in action.
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