Data Zone
Justification of Red List category
This species has a very small population which is suspected to be in decline. It has been eliminated from some sites by a combination of predation by introduced fish and entanglement in monofilament gill-nets, and is suffering habitat loss to rice cultivation. The rate of decline could accelerate in the next 16 years (three generations), although the rate of decline has not been quantified. Therefore, the species is listed here as Endangered.
Population justification
The population has been estimated to be only 2,000 individuals (A. Bamford in litt. 2018) (roughly equating to c.1,300 mature individuals), although it has been suggested that the species may have been difficult to find for some time (A. Konter in litt. 2018). Indeed there has been suspicion that the population may have been very low for a while (e.g. potentially 1,500-2,500 individuals; M. Rabenandrasana in litt. 2007). Given there is some uncertainty, and that these are only rough estimates, the population size has been placed here in the range 1,000-2,499 mature individuals.
Trend justification
The species is considered to be in decline owing to habitat loss, introduced species and bycatch. This decline is expected to accelerate over the next 16 years (three generations) as wetlands are increasingly targeted for cultivation and the species becomes more restricted to small wetlands that are unused by humans (O. Langrand in litt. 2007, M. Rabenandrasana in litt. 2007, H. G. Young in litt. 2007), but the rate of decline has not been accurately quantified.
Tachybaptus pelzelnii is still widespread and reasonably common in western and central Madagascar, with pairs or individuals on many small lakes. Surveys in the late 1990s recorded the species at 25 Important Bird Areas distributed throughout Madagascar (ZICOMA 1999), but it is suspected to be undergoing rapid declines. On Lake Alaotra, the number of Tachybaptus (including a small proportion of T. rufolavatus) declined from several hundred in 1985 to 10-20 in 1993 and to none in 1999 (ZICOMA 1999). Several hundred individuals may survive in the forested lakes of the northwest plateau, where Aythya innotata survives, and at one other lake complex (H. G. Young in litt. 2012, A. Bamford in litt. 2018). However, elsewhere the species may only occur in very small numbers (A. Bamford in litt. 2018, R. Safford in litt. 2018). The present decline in the population is expected to accelerate over the next 10 years as increasing wetland conversion and overfishing continues to restrict the species to small lakes that are inaccessible and unsuitable for human use (O. Langrand in litt. 2007, M. Rabenandrasana in litt. 2007, H .G. Young in litt. 2007).
Behaviour This species is sedentary but will disperse in search of suitable habitat (del Hoyo et al. 1992). Breeding has been observed during the months of August to March (Langrand 1995). Breeding pairs are territorial but sometimes nest close to one another, and groups of 150 individuals have been recorded (del Hoyo et al. 1992, Fjeldså 2004). Habitat The species was thought to prefer shallow, freshwater lakes and pools, with a dense covering of lily-pads Nymphaea (del Hoyo et al. 1992, Langrand 1995, Fjeldså 2004), but has also been found in several much deeper lakes (H. G. Young in litt. 2012). It occasionally occurs in brackish waters and slow-flowing rivers (del Hoyo et al. 1992, Langrand 1995, Fjeldså 2004). It appears to be capable of breeding in the above-mentioned habitats, including small temporary lakes (ZICOMA 1999), where a suitable covering of vegetation exists. Diet It probably feeds mainly on insects, but is also known to take small fish and crustaceans (Langrand 1995, Fjeldså 2004). Breeding site The nest is a floating structure of aquatic plants, anchored to offshore vegetation, particularly waterliles (Fjeldså 2004). Clutch-size is 3-4 (Fjeldså 2004). Breeding was recorded year round, but is likely seasonal at a given site (Safford and Hawkins 2013).
The most serious threat in the west is from reduction of habitat, especially conversion for rice cultivation and cash crops (O. Langrand in litt. 2007, H. G. Young in litt. 2007). In addition, the use of pesticides and fertilisers in agriculture is increasing and freshwater ecosystems in Madagascar are severely degraded by the proliferation of exotic aquatic plants such as Eichhornia and Salvinia spp. (O. Langrand in litt. 2007). All grebe species in Madagascar are extremely threatened by the intensification of fishing activities (H. G. Young in litt. 2007), and death through entanglement in monofilament gill-nets are probably a significant threat. The species is apparently considered a delicacy (H. G. Young in litt. 2012), but its low density may mean that it is only taken opportunistically during fishing activity (J. Westrip in litt. 2018). The introduction of exotic fish represents an additional threat (O. Langrand in litt. 2007, H. G. Young in litt. 2007); e.g. at Lake Alaotra, adults are predated by carnivorous snakehead fish Channa spp. (H. G. Young in litt. 2007). The introduction of exotic herbivorous fish (Coptodon zillii) has considerably limited the development of aquatic vegetation and favoured the Little Grebe T. ruficollis (Langrand 1995). Hybridisation with T. ruficollis has been suggested as an additional threat (Langrand 1995), but there is no supporting evidence (ZICOMA 1999).
Conservation Actions Underway
It is recorded from six protected areas, but numbers within them are small. To assess and prioritise wetlands for protection, a monitoring procedure has been proposed using birds, particularly T. pelzelnii, as indicators (Langrand and Goodman 1995). The Malagasy government has recently ratified the Ramsar Convention, and this may herald improved conservation measures for wetlands.
25 cm. Small grebe with distinctive facial pattern. In breeding plumage, blackish cap and line down neck, reddish rear ear-coverts and sides of neck, pale grey cheeks, throat and foreneck, and narrow whitish line under eye between cap and ear-coverts. Reddish eye, black bill with slight whitish tip. Pale brown underparts, dark brown-grey back. Similar spp. From other grebes by greyish cheeks and front of neck, lack of gape-wattles, and white line between cap and ear-coverts. Also, from Alaotra Grebe T. rufolavatus by red eye. Hints Often on small lakes and forested wetlands, where it is easily missed, but also on larger water bodies, including rivers, where it may be found among fringing vegetation.
Text account compilers
Khwaja, N., Calvert, R., Ekstrom, J., Shutes, S., Starkey, M., Evans, S.W., Symes, A., Taylor, P.B., Westrip, J.
Contributors
Rabenandrasana, M., Konter, A., Langrand, O., Hawkins, F., Safford, R., Bamford, A., Young, G., Westrip, J.
Recommended citation
BirdLife International (2024) Species factsheet: Madagascar Grebe Tachybaptus pelzelnii. Downloaded from
https://datazone.birdlife.org/species/factsheet/madagascar-grebe-tachybaptus-pelzelnii on 22/11/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 22/11/2024.