Under these drastically changing conditions, the struggle to survive favored the larger birds with deep, strong beaks for opening the hard seeds. Smaller finches with less-powerful beaks perished.

and the tree finch has a parrot-shaped beak suited for stripping bark to find insects. The Grants have focused their research on the medium ground finch, Geospiza fortis, on the small island of ...

A close up of the large ground finch <i>Geospiza magnirostris</i> that competed ... and colleagues was titled, "A beak size locus in Darwin's finches facilitated character displacement during ...