Data Zone
Justification of Red List category
This species occurs at a greater number of locations than was once thought, however there has been a continuing reduction in the extent and quality of habitat and it has a very small breeding range rendering it susceptible to stochastic events and human impacts. It is therefore classified as Vulnerable.
Population justification
Point counts and surveys of density conducted in 2002-2004, indicate a minimum population size of 2,500 pairs or 5,000 mature individuals, roughly equivalent to 7,500 individuals in total.
Trend justification
Although this species can persist in degraded habitats, it is present at lower densities than in low-altitude natural forests which are being cleared for cultivation and timber (del Hoyo et al. 2009), hence the population is suspected to be declining: the likely rate of decline has not been quantified.
Dicrurus waldenii occurs sparsely and locally on Mayotte (to France) in the Comoro island group. It is fairly widespread in the humid northern and western parts of the island, but may have a restricted ability to disperse between patches. It is found commonly over 200 m around Mts Hachiroungou, Mtsapéré, Combani and Bénara, Sohoa Forest, and at lower altitude along the west coast. It is also found at lower densities in areas of degraded habitats between the four mountains, and in mangroves at Dzoumonyé-Bouyouni, Miréréni-Chirongui and Tsingoni-Mroale-Soulou. It is absent from the entire southern peninsula, Mt Choungui and the lowland dry forests of Dapani-Sazilé (del Hoyo et al. 2009). Research up to 1994 showed it to be more abundant than Grand Comoro Drongo D. fuscipennis, with a population of at least 100 individuals (Louette et al. 1993, M. Louette in litt. 1999, Stevens and Louette 1999). However, point counts and surveys of density conducted in 2002-2004, indicate a minimum population size of 2,500 pairs (Rocamora 2004).
It occurs at the margins of evergreen forest (Benson 1960), in secondary forest, thickets and plantations (Safford and Evans 1992), and also on the coast in mangroves and littoral woodland (Louette et al. 1993, R. Safford in litt. 1999, Safford 2001). It also occurs at low densities in areas with forest patches alternating with Ylang-ylang plantations, orchards, forest clearings and agricultural fields (del Hoyo et al. 2009). Recent research suggests that the species prefers higher altitude, possibly wet, locations and is more abundant in larger forest patches, and those with a higher percentage cover of tall trees (Stevens and Louette 1999). It is insectivorous, and cicadas make up almost half of the prey items taken (del Hoyo et al. 2009). It may also take small vertebrates, although this is yet to be recorded (del Hoyo et al. 2009). Nesting has been observed between September and February. The nest is a solid round cup made of intertwined plant fibres built on a fork in a variety of tree species. It has a clutch-size of one-three eggs (del Hoyo et al. 2009). The incubation period is 19-21 days, followed by a fledging period of 17-25 days (M. Louette in litt. 2007, del Hoyo et al. 2009). Juveniles are dependent for one month after fledging and then remain with their parents until the start of the next breeding season (del Hoyo et al. 2009).
Deforestation for cultivation and timber is probably the greatest threat given that Mayotte's dense human population is growing steadily and the majority are involved in traditional food cultivation (del Hoyo et al. 2009). Furthermore, the network of reserves protecting its range do not have formal protection under French law (G. Rocamora in litt. 2010). The mangroves around Baie de Bouéni are threatened by heavy sediment loads from the deforested interior. Devastating cyclones seem to occur about every ten years (Louette et al. 1988, Safford 2001). The potential introduction of new nest predators is an important threat, and nest failure due to predation may already be as high as 75% (del Hoyo et al. 2009).
Conservation Actions Underway
Although forest cover has declined (6,000 ha, 25% of Mayotte's forests, disappeared between 1949 and 2002), a network of forest reserves totalling c.4770 ha now covers all remaining natural forests (del Hoyo et al. 2009). The most important of these for D. waldenii are probably Combani (3 km2), Majimbini (13 km2), Dzoumonyé (4 km2), Tchaourembo, Voundzé, and Hajangoua (Safford 2001). A bird monitoring scheme began in 2008 initiated by the Direction de l'Environnement et du Développement Durable of the Collectivité de Mayotte, which should soon provide the first population trend for the species (G. Rocamora in litt. 2010).
28 cm. Large, black bird with very long, deeply forked tail. Black plumage with deep greenish blue gloss. Tail fork shows the extremities splayed out, imparting a suggestion of a lyre shape. Bill black, strong; heavier and longer than those of D. adsimilis and D. macrocercus. Feet black. Iris red. Sexes alike, with males tending to be slightly larger. Juvenile brownish-black with less gloss, slightly paler underparts and not so well-developed tail fork. Voice Soft plitt plitt when hawking insects. Buzzing notes and scratchy cries including a loud tyok repeated several times, squaa-aa-kuchuk and throaty choo-kroo-kreech when alarmed at the nest. Song is a harsh jumble of chirps and squeaks. Pairs perform duets in their territories throughout the breeding season. Imitates call of other bird species.
Text account compilers
Calvert, R., Ekstrom, J., Pilgrim, J., Symes, A., Taylor, J., Warren, B., Ashpole, J & Westrip, J.
Contributors
Louette, M., Rocamora, G. & Safford, R.
Recommended citation
BirdLife International (2024) Species factsheet: Mayotte Drongo Dicrurus waldenii. Downloaded from
https://datazone.birdlife.org/species/factsheet/mayotte-drongo-dicrurus-waldenii on 23/11/2024.
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 23/11/2024.