Charles Darwin extensively studied pigeons to illustrate artificial selection. Domestic pigeon breeds showed him how deliberate breeding could produce striking differences within a single species.
Darwin became especially interested in fancy pigeons during the 1850s and kept a dovecote at Down House. He communicated with pigeon breeders, examined many breeds, and compared traits such as body shape, beak form, plumage, colouring, and behaviour. Breeders selected birds with desired characteristics and repeatedly bred them, causing those traits to become more pronounced over generations.
In On the Origin of Species, published in 1859, Darwin used pigeon breeding as a familiar example of variation and selection. He argued that if human breeders could produce dramatically different varieties through selective breeding, nature could also favour inherited differences over many generations. Artificial selection was directed by people; natural selection, in contrast, operates through environmental pressures and reproductive success.
Darwin did study other domesticated animals and plants, so pigeons were not his only example. They were particularly persuasive because breeds that looked remarkably different could still interbreed and trace their ancestry to the rock pigeon. The birds were therefore a model for understanding variation without treating every breed as a separate species.