Aldabra Drongo
Dicrurus aldabranus
Passeriformes Order – Dicruridae Family
INTRODUCTION:
The Aldabra Drongo is endemic to Aldabra Atoll in Seychelles Islands. It has restricted range on the four main islands of the atoll. It occurs in Aldabra Nature Reserve where the habitat is protected, but nest-predation by cats and rats limits the population size, although there is no evidence of decline.
The Aldabra Drongo is currently listed as Near Threatened.
DESCRIPTION OF THE BIRD:
Biometrics:
Length: 23 cm
Weight: 40-53 g
The Aldabra Drongo has glossy black plumage overall. The dark greenish-blue gloss is duller on both flight feathers and rectrices. The long tail (13-14 cm) is slightly forked, with outer rectrices slightly curved outwards. The worn plumage is browner.
On the black head, the long nasal and frontal feathers are curved forwards and slightly upwards.
The strong bill is black and slightly hooked. The eyes are red. Legs and feet are black.
Male and female are similar, but the female has shorter nasal/frontal feathers.
The immature has grey-brown upperparts except for the white uppertail-coverts. Wing-coverts and secondaries have white edges, and numerous feathers have buffy tips. Wings and tail are shorter.
The underparts are mostly white with some amounts of buffy or brownish-grey. The eyes are brown, not red.
RANGE:
The Aldabra Drongo occurs on the four main islands of Aldabra Atoll including Grande Terre, Malabar, Polymnie and Picards, and also on neighbouring islets.
HABITAT:
The Aldabra Drongo frequents wooded habitats, dense scrub, Casuarina equisetifolia coastal forest and mangroves.
The nesting-sites are mainly found in Casuarina and mangrove woodlands where the birds nest in tall trees.
CALLS AND SONGS:
The Aldabra Drongo is a noisy, vocal species with very varied repertoire.
The contact call is a nasal, wheezy “oink-eugh”. In flight, it gives high-pitched “eugh-eugh-eugh”. The alarm call is a harsh, nasal “chirr” and it drives away intruders from the nest by chasing them while giving musical whistles followed by two harsh notes, described as “ti-ti-you caw caw” repeated rapidly.
We can hear a soft, high-pitched twittering given by both mates during the courtship displays.
BEHAVIOUR IN THE WILD:
The Aldabra Drongo feeds on large insects, small geckos and other lizards. Insect’s diet includes cicadas, grasshoppers and various Diptera species.
It hawks insects on the wing while gliding from perch. The prey is pursued by flying between patches of vegetation and by flycatching. It also catches insects from branches and trunks.
It can be seen hunting at night around artificial lights, and also at dusk over beaches. It may sometimes take the prey in claws, but more usually with the bill.
The Aldabra Drongo is often seen alone or in family groups of 2-5 individuals foraging together. They forage between 2 and 8 metres above the ground and are conspicuous when perched.
The Aldabra Drongo is monogamous and very territorial during the breeding season. It is very aggressive against intruders, including larger birds such as herons, frigatebirds, boobies, crows, raptors, doves, gulls… and humans!
The courtship behaviour includes duets between mates. During displays, both birds are facing each other while shaking vigorously their wings and wagging their tails from side to side. These displays are accompanied by soft, high-pitched chatter. The male may sometimes take a dead leave and offer it to the female.
The Aldabra Drongo is resident.
It is agile while foraging in typically undulating flight.
REPRODUCTION OF THIS SPECIES:
The laying usually occurs between November and February, and chick-rearing coincides with the start of the rainy season involving insect abundance.
The nest is a round cup strongly woven in a fork towards the end of a thin horizontal branch. It is placed between 2 and 8 metres above the ground, sometimes higher, up to 13 metres. The nest is built over an open area or near water in mangroves, and usually in tall trees.
It is made with plant fibres, needles or twigs, dry grass, leaves and spider webs. It is built by both mates in 10-20 days.
The female lays 1-3 white to creamy-white eggs with dark markings. Both adults incubate during 16-18 days. The chicks are fed by both parents with insects. They fledge 15-19 days after hatching, but they still depend on adults for several weeks. They remain in family groups until at least the following breeding season.
PROTECTION / THREATS / STATUS:
The breeding success is very low due to high level of nest predation by crows, cats, rats, herons, coucals, falcons… However, a replacement clutch often follows nest-predation.
The Aldabra Drongo has small range and the population was estimated at 1,500 individuals, equating to 1,000 mature individuals in 1983. Surveys conducted between 2002 and 2013 showed stable population trend.
The Aldabra Drongo is currently listed as Near Threatened.
Fr: Drongo d'Aldabra
Ang: Aldabra Drongo
All: Aldabradrongo
Esp: Drongo de Aldabra
Ita: Drongo di Aldabra
Nd: Aldabradrongo
Sd: aldabradrongo
Text by Nicole Bouglouan
Sources:
HANDBOOK OF THE BIRDS OF THE WORLD Vol 14 by Josep del Hoyo-Andrew Elliot-David Christie - Lynx Edicions – ISBN: 9788496553507
The Birds of Africa: Volume VIII: The Malagasy Region: Madagascar, Seychelles, Comoros, Mascarenes - Par Roger Safford, Frank Hawkins – ISBN: 1408190494, 9781408190494- Editeur: A&C Black, 2013
CREAGUS – Don Roberson - Dicruridae
Drongos - From Wikipedia, the free encyclopedia
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