EX
Alaotra Grebe Tachybaptus rufolavatus



Justification

Justification of Red List Category
Thorough surveys of Lake Alaotra in 1989, and further surveys in 2004 and 2009 failed to find any evidence of the species. Considering the last confirmed sighting of the species was in 1982, and in view of the threats to the species, its lack of mobility and restricted range, this species is now considered to be Extinct.

Population justification
None are believed to remain in existence.

Distribution and population

Tachybaptus rufolavatus was endemic to Madagascar and known chiefly from Lake Alaotra (ZICOMA 1999). There were no direct observations since 12 were seen at Lake Alaotra in December 1982, and two were seen (in addition to several apparent hybrids) near Andreba on Lake Alaotra in September 1985. Individuals with some characteristics of the species were also seen on Lake Alaotra in 1986 and 1988 (Hawkins et al. 2000). A survey in 1999 and visits in 2000 found no individuals (of this or any species of Tachybaptus) on Lake Alaotra or surrounding lakes. Records outside the Lake Alaotra region were unreliable as species was probably incapable of prolonged flight, so in all likelihood never occurred very far from Lake Alaotra (ZICOMA 1999, Hawkins et al. 2000). A recent visit to Lake Amparihinandriamabavy failed to find any grebes (F. Hawkins in litt. 2009). It is now considered Extinct, as no suitable wetlands remain unsurveyed in the Alaotra region (G. Young in litt. 2009).

Ecology

Behaviour This species was presumed to be strongly sedentary since its small wings render it unable to fly long distances. Some movements to highland lakes and ponds other than Lake Alaotra were thought to have occurred as a result of the degradation of its preferred habitat, as opposed to representing habitual movement (del Hoyo et al. 1992). It was usually found in pairs, sometimes in association with T. ruficollis (Langrand 1990). It was thought to have a flexible breeding season, with historical records of breeding in April-June and in January-March (del Hoyo et al. 1992). Habitat Lake Alaotra is a large, shallow, brackish lake. Its shores were historically covered with dense vegetation including papyrus and reeds, which may have been important for this species (del Hoyo et al. 1992). Diet It fed almost exclusively on fish (Langrand 1990). Breeding site Nothing was known of its breeding ecology (Langrand 1990).

Threats

Several major factors contributed to this species's extinction. The use of monofilament nylon gill-nets at Lake Alaotra has proliferated recently, to the extent that they now cover a large part of the open lake. They undoubtedly kill many diving waterbirds; however the introduction of this fishing method probably only happened after the grebe had already been greatly reduced in number or had disappeared. It is also likely that the introduction of the carnivorous fish Micropterus salmoides and Channa striata has been a major factor in the species's decline and extinction (ZICOMA 1999). Soil erosion from deforested hillsides, agriculture and sedimentation have lowered the water quality of the lake. Introductions of exotic plants, mammals and fish, especially Tilapia, probably depleted essential foods for the species (Pidgeon 1996), and natural habitat has been lost through the conversion of marsh areas to rice farms (Wilmé 1994). Hybridisation with T. ruficollis, probably a recent colonist from Africa, has occurred in the past and may have been the major contributing factor in this species's decline (Hawkins et al. 2000). Poaching is also thought to have played a significant role in the extinction of the species (Wilmé 1994).

Identification

25 cm. Small grebe with rather long, stout bill and short wings. In breeding plumage, dark, oily blackish cap, and line down nape. Pale cinnamon on throat and ear-coverts, with mottled dusky and rufous underparts and dark brownish back. Characteristic pale yellow iris, and variable pale gape-wattles. Solid, blackish bill with white tip. Similar spp. From other grebes by pale iris, dusky underparts and longer bill. Little Grebe T. ruficollis lacks pale cinnamon throat and lower ear-coverts. Madagascar Grebe T. pelzelnii has whitish line under eye. Hints Dives for small fish near fringing aquatic vegetation, often with other species of grebe.

Acknowledgements

Text account compilers
Benstead, P., Bird, J., Calvert, R., Ekstrom, J., Evans, M., Khwaja, N., Malpas, L., Shutes, S., Starkey, M., Symes, A., Martin, R

Contributors
Young, G., Hawkins, F.


Recommended citation
BirdLife International (2019) Species factsheet: Tachybaptus rufolavatus. Downloaded from http://www.birdlife.org on 06/12/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 06/12/2019.