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Photograph of an Atitlán Grebe. Unknown copyright licence.

Podilymbus podiceps gigas (Griscom, 1929)

The bird has been considered a large and flight-impaired (Livezey 1989) subspecies of Pied-billed Grebe Podilymbus podiceps (Howell & Webb 1995). (BirdLife International 2004; BirdLife International 2006)

The Atitlán Grebe looks like a larger version of the Pied-billed Grebe (Podilymbus podiceps) with a few minor colour differences, like a darker head, neck and belly (Griscom 1929; Hunter 1988). The upperparts are dark greyish brown with an almost black coloured head and neck. The underparts are dark grey flecked with white. The bill is whitish with a dark vertical band in summer adults. The eye's iris is dark brown. The feet are blackish brown. The chick is zebra-striped. (Fuller 2000) The Atitlán Grebe is almost twice as heavy as the Pied-billed Grebe, but both have roughly the same wing lengths (Hunter 1988). The Atitlán Grebe has a length of 50 cm and the length of the wing is 125-145 mm (Fuller 2000). The Atitlán Grebe is reported to be flightless (Hunter 1988).

The Atitlán Grebe was endemic to Lake Atitlán, Guatemala (LaBastille 1974). (BirdLife International 2004; BirdLife International 2006)

Image: range map of the Atitlán Grebe (in red). Created by Peter Maas for The Extinction Website. The copyright holder of this work has released it into the public domain. This applies worldwide.

Like other grebes, the Atitlán Grebe conducted spectacular courtship and territorial displays. Female and male Atitlán Grebes formed long-term partnerships and inhabited the same territory almost indefinitely. Two or three white eggs were usually laid. (Fuller 2000)

The Atitlán Grebe was first described in 1929 by the American ornithilogist Ludlow Griscom (Griscom 1929). The Atitlán Grebe population dropped from about 200 to 80 as a result of competition and predation by large-mouth bass Micropterus salmoides, introduced into the lake in 1960, but recovered to a high of 232 in 1975 when the numbers of bass plummeted (LaBastille 1984). However, increasing pressure on breeding sites from local reed-cutting and from tourism development, along with the murder of the government game warden for the national park during the political unrest of 1982 and falling lake levels following the earthquake of 1976, drove the population down to 50 in 1980 and to 32 in 1983 (LaBastille 1990). During 1987 it was announced that although a few pure individuals might survive, the species was biologically, if not actually, extinct, and at some time soon afterwards the last Atitlán Grebe died. (Fuller 2000; BirdLife International 2004; BirdLife International 2006)

The introduction of large-mouth bass Micropterus salmoides, increasing pressure on breeding sites from local reed-cutting and from tourism development, the murder of the government game warden for the national park and falling lake levels have led to the extinction of this species. 

Photo: a large-mouth bass photographed by Trisha M Shears 0n 21 February 2007. The copyright holder of this work has release it into the public domain. For more information see Wikimedia Commons.

Drowning in gill nets and disturbance by increasing boat traffic have also been suggested as contributory factors (Collar et al. 1994). Hybridisation between with the Pied-billed Grebe (Podilymbus podiceps) may have been a factor in the final extinction of this species (Hunter 1988). (BirdLife International 2004; BirdLife International 2006)

American ecologist, Anne LaBastille began her campaign to save the Atitlán Grebe in 1966. She raised the species' profile and the necessary funds for the establishment of a small refuge on the lake's banks. This refuge was left high and dry after the lake's water surface dropped by 6 metres (19 ft) in the mid 1970's. Thousands of reed clumps had to be transplanted. Edgar Bauer, one of the people who helped with this massive operation and along with Anne LaBastille one of the great promoters of the campaign to save this grebe was gunned down by unknown assassins in 1982. Nobody dared to step forward to replace him, because of the political situation in Guatemala at the time. (Fuller 2000)

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The closest living relative of the Atitlán Grebe is the Pied-billed Grebe, Podilymbus podiceps. Since the Atitlán Grebe has become extinct, it is the sole extant member of the genus Podilymbus. (Fuller 2000; Wikipedia contributors 2007)

Image: a Pied-billed Grebe (Podilymbus podiceps) in Lake Patagonia (Arizona, USA). Photographed by Wikimedia Commons user 'Mdf' in 2005 and released under the GNU Free Documentation License.

IUCN Red List of Threatened Species: Podilymbus gigas

Atitlan Grebe (Podilymbus gigas) - BirdLife species factsheet

Atitlán Grebe - Wikipedia, the free encyclopedia

Ausgerottete Arten - Atitlan-Taucher

References

(Complete website)

Collar, N.J., Crosby, M.J. and Stattersfield, A.J. (1994) Birds to watch 2: the world list of threatened birds. Cambridge, U.K.: BirdLife International (BirdLife Conservation Series 04).

Fuller, E. 2000. Extinct birds. Oxford University Press, Oxford.

Griscom, L. 1929. Studies from the Dwight collection of Guatemala birds. Am. Mus. Novit. 379: 1-13.

Howell, S. and Webb, S. (1995) Noteworthy bird observations from Chile. Bull. Brit. Ornithol. Club 115: 57-66.

Hunter, L. A. (1988) Status of the endemic Atitlán Grebe of Guatemala: is it extinct?. Condor 90: 906-912.

La Bastille, A. (1990) Mama Poc: an ecologist's account of the extinction of a species. New York: W.W. Norton and Company.

LaBastille, A. (1974) Ecology and Management of the Atitlán Grebe, Lake Atitlán, Guatemala. Unknown: Wildlife Society (Wildlife Monographs No. 37). 

LaBastille, A. (1984) Drastic decline in Guatemala's Giant Pied-billed Grebe population. Environ. Conserv. 11: 346-348.

Livezey, B. C. (1989) Flightlessness in grebes (Aves: Podicipedidae): its independent evolution in three genera. Evolution 43: 29-53.

Wikipedia contributors (2007), "Atitlán Grebe," Wikipedia, The Free Encyclopedia, http://en.wikipedia.org/w/index.php?title=Atitl%C3%A1n_Grebe&oldid=173780788 (accessed December 24, 2007).

Zusi, R. L., and R. W. Storer. 1969. Osteology and myology of the head and neck of the Pied-billed Grebes (Podilymbus). Misc. Publ. Mus. Zool. Univ. Mich. 139: l-49.

Last updated: 29^th November 2007.

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