Charles Darwin’s finches

Somehow, many millions of years ago, a finch arrived on the Galapagos Islands. Did it float on a raft of greenery and logs from the mainland? This was long before a boat would have carried it across the thousand miles from the South America mainland.

The finch spread to the other islands of the Galapagos over time. To survive on each island, the finch adapted over many generations to the conditions, particularly the food sources that were available. Charles Darwin’s theory of evolution was based in large part on the finches he observed on the Galapagos Islands.

In a handy guidebook that we took along, “Birds, Mammals, and Reptiles of the Galapagos Islands” by Andy Swash and Rob Still, photos of the finches were spread out over 4 pages, and they looked a lot alike – except for their beaks. There are 13 Darwin finches currently on the islands and 13 different beaks.

The authors, and our guides, warned of great problems in identifying many of these birds. Still, it would be interesting to see how far we could get in trying to identify the finches we were able to photograph. The photos were not always very good, but we hoped good enough for our identification purposes. To guide novice birdwatchers (like us), a chart in the guidebook showed a profile of all the finches’ bills to help with identification.

Finch, sharp-beaked (young juv)

Our guide excitedly pointed to this very young sharp-beaked ground finch on Genovesa Island. These finches eat seeds usually, but on two other islands, Darwin and Wolf, have used their beaks to stab boobies and drink their blood. Their nickname has become “vampire” finch.

DSC06244

Only 4 finch species are found on Genovesa Island, including the warbler finch. Its thinner beak is good for probing for insects.

The beak on this male bird indicates it might be a large cactus finch. The beak works well for eating parts of the prickly-pear cactus.

The beak on this male bird indicates it might be a large cactus finch. The beak works well for eating parts of the prickly-pear cactus.

Santa Cruz Island is home to 9 species of Darwin finches. That makes it much more difficult to identify the birds we saw there. 3 of those species are uncommon, so we assumed that we could concentrate on the other 6.

We think this is a male cactus finch, but is it a small or medium? They are different species, and both quite common on Santa Cruz Island.

We think this is a male cactus finch, but is it a small or medium? They are different species, and both quite common on Santa Cruz Island.

his female small ground finch’s beak is refined for eating small seeds and parasites from tortoises and iguanas.

This female small ground finch’s beak is refined for eating small seeds and parasites from tortoises and iguanas.

The Darwin finches are only found on the Galapagos Islands.   They continue to change over time and continue to be a source of curiosity and wonder to all who see them.

One last note: In reading about the Darwin finches, it has been determined that they are not really “true finches” after all. Their closest relative in the bird family is a tanager. Who knew?

 

April 2016

 

About simpletravelourway

Beth and Joe enjoy simple travel.
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15 Responses to Charles Darwin’s finches

  1. Complete novice question: wouldn’t it have had to be two finches settling on Galapagos? Or can two species of birds together have offspring? I know … way too technical a question, but the solo bird floating on a log theory just got me thinking….

  2. plaidcamper says:

    A wonderful post! Lovely photographs, and what fun you must have had in trying to identify each finch. I really enjoyed this – thank you!

  3. Cliff Mail says:

    Nothing wrong with those photos. Looking at the size of them they would have had to hitch a ride on something. But I understand strong updrafts can deliver objects a long way. Interesting story, especially the distinct evolution on each island. We often never take time to consider the finer details of what we are seeing.

    • When in Guayaquil, we saw a good bit of debris (logs, tangled vines, clumps of plants, and birds perched on them) rafting down the river on the way out to sea, so perhaps rafting or as you say powerful winds.

  4. The trouble with finches is they don’t stay still long enough to get a good look at them, let alone take a photo. I’m impressed with all the great photos you collected.

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