The common ancestor of the finches probably had a pointy beak, and some species later developed blunt beaks better for crushing seeds.
Medium ground finches (Geospiza fortis) on the island Daphne Major, for instance, evolved pointier beaks after a drought in 1985 and 1986.
The Centrality of Finches to the Development of the Theory of Evolution
The first place to look for a record of the role of Darwin's finches in Darwin's thinking is in his published works, especially The Voyage of the Beagle (2) and The Origin of Species (3) where he argued for evolution by natural selection, an analogy for formation of new species.
We did not observe adult House Finches feeding the nestlings, although adult finches used nearby feeders with black oil sunflower seeds.
House Finches have been documented as interspecific brood parasites of Black Phoebe (Sayornis nigricans), Cliff Swallow (Petrochelidon pyrrhonota), and Hooded Oriole (Icterus cucullatus) (Shepardson 1915, Holland 1923); to our knowledge, however, our report is the first to document House Finch nestlings fledging from a host species' nest.
By the third night, the Finches had eaten all their strawberries, but they still had four little cakes and some whipped cream.
No matter how hard the Finches tried, they could never use up all the strawberries, whipped cream, and cake at the same time.
Huber studies the species called medium ground finches (Geospiza fortis).
These finches are demonstrating the kinds of changes that could lead to a split into two new species, Huber says.
The finches poke twigs or cactus spines into crevices to dig out insects, explains Sabine Tebbich of the Max-Planck Institute for Behavioral Physiology in Seewiesen, Germany.
Among woodpecker finches, birds in the dry areas probe with tools more frequently than birds in humid areas do, the researchers report.
The birds, commonly known as Darwin's finches, also possess physical traits that are highly inheritable, such as weight and bill size.
For most of the year, the finches subsiston seeds of varying size and hardness.
The loss of neurons in the MAN suggeststo Bottjer that zebra finches
are born with a wide capacity for possible notes and that later, once they've learned the species' songs, they discard the cells for notes they no longer need.