Darwin's finches continue to surprise scientists

Researchers at McGill University are providing new insight into one of the most studied organisms on the planet, Darwin’s finches in the Galápagos Islands. Until now, the range of the finches had not been sufficiently studied due to the treacherous nature of their habitat. 

However, an international team of researchers was able to track the birds on the island of Santa Cruz by using small electric backpacks. They found that the finches cover a lot of ground within 24 hours. 

Study lead author Marc-Olivier Beausoleil explained why this subject was necessary to examine. “Understanding the real space needs of these birds is crucial both to refine the interpretation of previous studies and to ensure the conservation of these birds in a landscape increasingly threatened by the expansion of urban areas.”

The researchers observed behaviors that they had not anticipated. For example, they found that the finches commute the equivalent of 30 soccer fields in a single day. The experts wondered why the finches traveled so far since, during the day, they rarely went more than 100 meters from their nests.

Although most birds don’t roost in groups during the breeding season, Darwin’s finches are an exception, according to the study. 

“Almost all the tagged finches left their breeding territories after sunset and moved four times the distance they normally cover in the daytime,” said Beausoleil. “The mysterious destination: a lush grove of poison apple trees (Hippomane mancinella) located by the sea where nearly a thousand finches gather nightly to rest.”

The question is, why would they do this? Carlos Camacho, a researcher at Instituto Pirenaico de Ecología and coordinator of the study explained that sleeping in the company of others helps the birds fight the cold and reduces the risk of predation.

“Although the advantages of this behavior are not as evident in a place where temperatures are mild and predators are scarce,” said Camacho. “This leads us to think that this behavior may have been inherited from their continental ancestors.” 

Even 150 years after Darwin proposed his theory of natural selection, his finches still have something to teach us. The researchers believe that their findings will help inform diversity conservation.

The research is published in the journal Ecology and Evolution.

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By Erin Moody , Earth.com Staff Writer