Cyanolanius

The blue vanga (''Cyanolanius madagascarinus'') is a bird species in the family Vangidae. It is in the monotypic genus ''Cyanolanius''. It is found in Comoros, Madagascar, and Mayotte, where its natural habitats are subtropical or tropical dry forest and subtropical or tropical moist lowland forest.

Taxonomy and systematics

In 1760, the French zoologist Mathurin Jacques Brisson included a description of the blue vanga in his ''Ornithologie'' based on a specimen collected on the island of Madagascar. He used the French name ''Le pie-griesche bleu de Madagascar'' and the Latin name ''Lanius Madagascariensis coeruleus''. The two stars (**) at the start of the section indicates that Brisson based his description on the examination of a specimen. Although Brisson coined Latin names, these do not conform to the binomial system and are not recognised by the International Commission on Zoological Nomenclature. When the Swedish naturalist Carl Linnaeus updated his ''Systema Naturae'' for the twelfth edition in 1766, he added 240 species that had been previously described by Brisson. One of these was the blue vanga. Linnaeus included a brief description, coined the binomial name ''Loxia madagascarina'' and cited Brisson's work. The species is now placed in the genus ''Cyanolanius'' that was introduced by the French naturalist Charles Lucien Bonaparte in 1854.

Subspecies

Three subspecies are recognised:
* ''C. m. madagascarinus'' (Linnaeus, 1766): Found in northern, eastern, and western Madagascar. Clements splits this subspecies from the Comoros subspecies and calls it the Madagascar blue vanga
* ''C. m. comorensis'' ( Shelley, 1894): Also known as the Comoros blue vanga, it is found on Mohéli in the Comoro Islands. It tends to be larger than ''madagarensis'' and is also exhibits slight differences in colour. It has occasionally been considered as distinct species
* ''C. m. bensoni'' Louette & Herremans, 1982: It is found on Grande Comore in the Comoro Islands. It is described from only a single immature specimen, and looks very similar to ''comorensis''. Doubts have been cast on whether it is a distinctive taxon.

Description

The blue vanga is long and weighs .

Adult males are bright blue in color, with a black line through the eye which extends to base of the bill, as well as above and below the bill. It has a paler blue eye-ring. The tail as well as edges and tips of the wings are black in colour. The underparts and throat are bright white in colour. Females tend to be slightly duller in colour than males, with the underparts also being off-white in colour with a pale orange or light buffy wash. The wings are slightly tinged greenish.

Juveniles have a grayish-blue head, with the rest of the upperparts being dark greenish olive. Their tail is similar in appearance to an adult female's, but has a duller green-blue pattern. The throat is dirty-white in colour, the rest of the underparts being olive-buff.

Colours of bare parts vary according to subspecies. ''C. m. madagarensis'' has a vivid pale or cold blue beak, with a dark tip and cutting edges in adult males, and a dark brown with similar pattern in adult female. Juveniles have a black bill with pale pink base. The iris is sky-blue or greenish blue in males, and brown in females and juveniles. The legs are black in male and gray in females.

''C. m. comorensis'' has a ultramarine blue beak with a black tip in males and a dark brown tip in females. The iris is pale blue in adults, while the legs and feet are black or dark slate in colour.

Vocalisations

Calls are described as a very characteristic ''tcccch'', which is sometimes repeated to form a ''chrr-crrk-crrk-crrrrk-crk-crk'', similar to the chabert vanga's call. The song can be faster or slower, and the first note is usually of a higher pitch. They also make a ''teea teea teea'' or a harsh ''scheet'', which is thought to be an alarm call. Race ''comorensis'' has similar calls, but also makes a grating ''erch-chhh-crkk-chh-chhh-chhh-crrk'' or a harsher ''crew-crew-crew''.''

Behaviour and ecology

Diet

Mainly feeds on insects, including beetles, crickets, cicadas, caterpillars, as well as spiders. They also occasionally feed upon berries. Birds on Mohéli have been recorded eating fruit.

It forages in the middle and upper levels of trees. Feeding often occurs while hanging upside down from its feet. Most food is gleaned from the substrate, and it also sally-gleans from branches and leaves. It usually forages in groups of up to 6 birds n the non-breeding season, and in pairs while nesting. It has also been observed foraging in mixed-species flocks throughout its range.

Breeding

The breeding season is thought to be from October–December. Juveniles are taken care of by both sexes. The observed nests were placed around above the ground, near a fork between near-vertical, slender branches. The nest is cup-shaped, and made out of fine twigs and a pale down-like material.

Eggs are pale blue to green and have mid-sized lilac-gray to red-brown speckles, which are the densest at the larger end. They are 19.9–21.2 × 15.8–16.2 mm in size.

Distribution

The species is found in northern, eastern, and western Madagascar, as well as on the islands of Grand Comore and Mohéli in the Comoros Islands. It inhabits the midstory and canopy of deciduous dry forests in the western part of its range, and evergreen humid forest in the west. It has also been observed in littoral forests, the adjacent second growth, and even in mangroves. It occurs up to an elevation of , although it has been reported up to elevations of .

It inhabits a variety of woodland on the Comoro Islands. It is known to inhabits habitats above an elevation of on Mohéli. On Grand Comore, it is mainly known from degraded forest patches with banana cultivation on the slopes of Mount Karthala at an elevation of .

Status

The nominate race on Madagascar faces few threats due to its large range and population. It is classified by the IUCN Red List as least concern. However, the subspecies on the Comoro Islands is threatened by a limited range, deforestation and habitat loss, and degradation of the habitat due to invasive plant species like '' Syzygium jambos'', ''Lantana camara'' and ''Clidemia hirta''.

References

{{Taxonbar, from=Q509183

blue vanga
Birds of the Comoros
Birds of Madagascar
Birds of Mayotte
blue vanga
Taxonomy articles created by Polbot
Taxa named by Carl Linnaeus