Professors make annual trip to study Galapagos finches' beaks

Peter and Rosemary Grant would fare well on "Survivor."

Living alone on a small, uninhabited island, communicating with the mainland only by radio and relying on a national park service's monthly delivery of drinking water have become second nature for this husband-and-wife research team.

Since 1973, the University ecology and evolutionary biology professors have made a yearly trip to Daphne Major in the Galapagos Islands, staying anywhere from six weeks to six months each time.

Part of the archipelago originally made famous by Charles Darwin, Daphne Major provided the Grants an ideal location for tracking evolutionary patterns in native animal populations.

With the help of the Darwin Research Station and the Galapagos National Parks authority, they gathered data with relatively few obstacles or interruptions.

Their resulting study, recently published in the journal Science, is "one of the true classics of evolutionary biology," John Burke, an Indiana University professor, said in the article.

Over three decades, the Grants focused their study on two indigenous species, the cactus finch and the ground finch.

"They were already famous in evolutionary biology before we started our work, and they seemed to us the most suitable group of birds for our ecological and evolutionary studies," Peter Grant said in an e-mail from Switzerland.

They found that the average beak size of the ground finch changed slightly according to food availability.

In 1977, a major drought hit the island, and many small-seeded plants were killed. Those finches that survived were those with larger beaks who were able to digest the larger seeds of the surviving plants.

In 1983, the rains returned, and the trend reversed. Average beak size decreased by 2.5 percent in the next generations of ground finches.

The 1983 rains killed off many female cactus finches, causing male cactus finches to interbreed with ground finch females. The resulting offspring displayed blunter beaks than customary in pure cactus finches, showing their ground finch heritage.

Get the best of the ‘Prince’ delivered straight to your inbox. Subscribe now »

Grant said since the finches are "fairly tame" they are easy to locate and handle.

The Grants marked each newly hatched finch individually, attaching several identification bands to the legs of each finch. Later, using large nylon "mist-nets," the Grants captured and measured the grown nestlings.

The isolation of the island, located 600 miles off the coast of Ecuador, aided their study. In 1934, the government of Ecuador set aside most of the Galapagos islands as wildlife sanctuaries. Daphne Major's pristine environment prevented the Grants from having to worry about outside influences skewing their data.

Early study in England's countryside led to the Grants' initial interest in natural history.

"As students," Grant said, "we became fascinated with theoretical ideas in evolutionary biology, and the power of scientific studies to answer questions."

Despite their comprehensive study, the Grants have not yet satisfied their curiosity about the evolutionary patterns they have observed on Daphne Major.

"We are continuing the study because we have not answered all our questions about the evolutionary changes that are taking place in the study populations," Grant said.

Currently compiling research for a separate study in Switzerland, the Grants plan to return to Daphne Major in the near future, hoping that the measurement of small changes will bring them closer to answering large evolutionary puzzles.