What was the species of bird that Darwin observed and thought to be wrens warblers and blackbirds?

Darwin observed several species of finches during his time in the Galápagos Islands, which he initially thought were wrens, warblers, and Blackbirds. These finches, later known as Darwin's finches, played a crucial role in his formulation of the theory of natural selection, as he noted their variations in beak shape and size adapted to different ecological niches.