Source: Quanta Magazine; Courtesy Peter and Rosemary Grant
Daphne Major in the Galapagos chain.
Yes, 40 years of field research on that half a square km size island, tracking, generation after generation, changes in body and beak size of different species of ground finches. Lately, they have supplemented their morphologic and bird song data with genomic analysis to get an understanding of the genetic underpinnings of morphologic change.
Rosemary and Peter Grant interviewed about their epic evolution watch:
"The diminutive island wasn’t a particularly hospitable place for the Grants to spend their winters. At less than one-hundredth the size of Manhattan, Daphne resembles the tip of a volcano rising from the sea. Visitors must leap off the boat onto the edge of a steep ring of land that surrounds a central crater. The island’s vegetation is sparse. Herbs, cactus bushes and low trees provide food for finches — small, medium and large ground finches, as well as cactus finches — and other birds. The Grants brought with them all the food and water they would need and cooked meals in a shallow cave sheltered by a tarp from the baking sun. They camped on Daphne’s one tiny flat spot, barely larger than a picnic table.
...They visited Daphne for several months each year from 1973 to 2012, sometimes bringing their daughters. Over the course of their four-decade tenure, the couple tagged roughly 20,000 birds spanning at least eight generations. (The longest-lived bird on the Grants’ watch survived a whopping 17 years.) They tracked almost every mating and its offspring, creating large, multigenerational pedigrees for different finch species. They took blood samples and recorded the finches’ songs, which allowed them to track genetics and other factors long after the birds themselves died. They have confirmed some of Darwin’s most basic predictions and have earned a variety of prestigious science awards, including the Kyoto Prize in 2009".
indefatigable to the end..
"Do you plan to go back to Daphne?
RG: We stopped intensive work after 40 years, but we do plan to go back.
PG: The oldest person died at 122 years old. That means we have 40 more years".
Habitats varied on different islands. Darwin realized that sometime in the distant past one ancestral population of finches must have immigrated from the South American mainland and then diverged into several morphologically distinct species, each a fit to its habitat. That was one of the threads of reasoning he weaved into a more comprehensive theory of common descent and evolution through natural selection.
The book, Beak of the Finch by Jonathan Weiner, is a bit dated but is still a riveting account of Rosemary and Peter Grant's research.
Update: @avinashtn alerted me to the Grant's book "40 Years of Evolution".