Atitlán Grebe, Podilymbus gigas

The Atitlan Grebe (Podilymbus gigas), also known as the Giant Grebe, Giant Pied-billed Grebe, and Poc, is an extinct species of water bird. It was endemic to Lago de Atitlan in Guatemala at an altitude of 5,600 feet above sea level. Before the bird became extinct, it was extensively studied by American ecologist Anne LaBastille for 25 years. Due to this, its decline is comprehensively known.

The Atitlan Grebe reached a length of about 18 to 19.6 inches. Its appearance was similar to the Pied-billed Grebe. The plumage was mainly dark brown with white-freckled flanks. The underparts were dark gray flecked with white. The head was almost black and the neck was flecked with dark brown in the spring and white in the winter. Its legs were slate gray. The bill had a bold black vertical band in the middle. The color of the bill varied from white in the spring to brown in other seasons. The irises were brown. It had small wings and was flightless.

The nest of the Atitlan Grebe consisted of 4 to 5 white eggs. Both parents reared the hatchlings.

The Atitlan Grebe became extinct mostly due to introduction of smallmouth bass and largemouth bass into Lake Atitlan. These invasive species reduced the crabs and other small fish that Atitlan Grebes depended on for food. The fish even killed grebe chicks swimming on the surface. Their decline began in 1958 and in 1965 only 80 individuals remained.

Conservation efforts by LaBastille helped the Grebe make a slow, but steady recovery, bringing the population to 210 individuals by 1973. But after the 1976 Guatemalan earthquake, the lake bed fractured, leading to a drastic drop in water levels. The water level decline further harmed the Grebe population, with only 32 individuals known by 1983. The last two birds were seen in the wild in 1989, and soon after the Atitlan Grebe was declared extinct.

LaBastille wrote a book about the Atitlan Grebe, called Mama Poc.

Image Caption: Diving Grebe. Credit: Brocken Inaglory/Wikipedia (CC BY-SA 3.0)