Darwin's Finches

What are Darwin's Finches?

Charles Darwin was a naturalist who was on the British survey ship, the HMS Beagle. During his 5 year trip, Darwin visited the Galapagos and collected samples of birds from each island (Biology Coloring Workbook). These finches are famous or well known examples that illustrate the concept of evolution. The finche's are now considered a perfect example of adaptive radiation where one species diversifies into a wide range of habitats. That also goes with the finches being a classic example of evolution (http://www.hras.org/sw/sw11-04.html). Darwin did research on the finches and categorized them by their eating habits but mainly by their beaks. He noticed that their beaks vary by different shapes and sizes on the different islands (http://www.truthinscience.org.uk/tis2/index.php/component/content/article/53.html).

Darwin's Finches

What are the specific differences between Darwin's Finches?

Charles Darwin categorized the different species of finches based on their eating habits and the shapes and sizes of their beaks. Darwin found 13 different species of the finches but 6 of them are the warblerlike finch, the insect-eating finch, the woodpeckerlike finch, the plant-eating finch, the ground finch, and the cactus-eating finch(biology coloring workbook). The warblerlike finch has the smallest beak in the size and shape (http://www.doc.ic.ac.uk/~kpt/terraquest/galapagos/wildlife/island/finch.html). The insect-eating finch has a very heavy beak that allows the finch to be able to grab insects for food. The next finch out of the six is the woodpeckerlike finch, this finch lives in trees and has a long and narrow beak similar to a woodpeckers so it can drill holes in the tree. This finch has no tongue so it uses a cactus spine to dig out insects. The plant-eating finch also lives in trees but has a beak designed for eating only plants (biology coloring workbook).  Next is the ground finch which there is actually four different kinds of ground finches. The large ground finch is the largest of the ground finches and has a massive bill. The small ground finch has a dainty, short, pointed bill. The medium ground finch is between the small and large finches beaks and the upper mandible is always greater than the depth of the bill. The last ground finch is the sharp beaked or vampire finch which is very similar to the small ground finch but the bill is longer and more curved and this finch feeds off of other birds blood (http://www.galapagosexpeditions.com/islands/darwin-finches.php). The last finch of the six is the cactus-eating finch which feeds off of cactus seeds and uses its beak to crush the seeds and since the seeds are usually soft, their bill is pretty small (biology coloring workbook).

Darwin's Finches

Why are the finches on different islands so different?

The difference between where the finches evolved from all started from the finches diversifying into many different forms and adapting to their surroundings because they flew to different islands that offered more food for them to be able to survive (http://ncse.com/files/pub/evolution/excerpt--evolution--fb.pdf).From year to year the weather on Galapagos Islands changes dramatically which has a huge effect on the finches diet. Certain finches can only eat seeds while other can eat bigger foods like plants.When the weather changes, it changes the availability of certain foods which led to the conclusion of how and why the finches diversified onto many different islands (http://www.pbs.org/wgbh/evolution/library/01/6/l_016_01.html). About two-three million years ago there weren't as many islands as there are today. New islands developed from the eruption of volcanoes and over time those new islands climates started to cool and changed the vegetation on certain islands which led to the conclusion of how certain finches diversified there because of the differences between the vegetation (http://edoc.bbaw.de/volltexte/2009/1204/pdf/VII_03_Grant.pdf).