Big Bird, also known as the Big Bird lineage, is one of the species of

Darwin's finches Darwin's finches (also known as the Galápagos finches) are a group of about 18 species of passerine birds. They are well known for being a classic example of adaptive radiation and for their remarkable diversity in beak form and function. They ...

that is exclusively present on

Daphne Major Daphne Major is a volcanic island just north of Santa Cruz Island and just west of the Baltra Airport in the Archipelago of Colón, commonly known as the Galápagos Islands. It consists of a tuff crater, devoid of trees, whose rim rises above the ...

of the

Galápagos Islands The Galápagos Islands () are an archipelago of volcanic islands in the Eastern Pacific, located around the equator, west of the mainland of South America. They form the Galápagos Province of the Republic of Ecuador, with a population of sli ...

. It originated from a single male

Española cactus finch The Española cactus finch (''Geospiza conirostris''), is a species of bird in the tanager family Thraupidae. It is one of Darwin's finches, and is endemic to the Galápagos islands, where it is restricted to Española, Genovesa, and the Darwin ...

(''Geospiza conirostris'') that immigrated to Daphne Major in 1981, which founded a hybrid lineage by breeding with a female medium ground finch and creating 5 offspring. It resembles the medium ground finch but is relatively larger, hence, the name. The offspring tend to breed only with their own family members, thereby giving rise to reproductive isolation and undergoing speciation. Discovered by the research team of

Peter and Rosemary Grant Peter Raymond Grant (born October 26, 1936) and Barbara Rosemary Grant (born October 8, 1936) are a British married couple who are evolutionary biologists at Princeton University. Each currently holds the position of emeritus professor. They ...

, the formation of Big Birds as a distinct species is considered as an instance of observed

speciation Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within ...

and as a process of evolution by

natural selection Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the Heredity, heritable traits characteristic of a population over generation ...

. The original Big Bird bred with a female medium ground finch to create five bigger offspring (F₁). A drought from 2003–2005 wiped out all of the population except for a F₃ brother-sister pair, which went on to mate with each other when the rain returned. All surviving Big Birds are the offspring of these two finches, coded 19228 and 19798 in the 2017 ''Science'' article. Their father was descended from a F₁ hybrid male and a resident female medium ground finch. Their mother was descended from two F₁ hybrids. As a result, all current Big Birds (the last generation as of 2017 being 3 F₆ birds) have pedigree from the immigrant ''Geospiza conirostris''.

References

{{Taxonbar, from=Q48812340 Geospiza Endemic birds of the Galápagos Islands Evolution of birds Bird hybrids