Irenidae – Fairy-bluebirds
The two fairy-bluebirds are small passerine bird species found in forests and plantations in tropical southern Asia and the Philippines. They are the sole members of the genus Irena and family Irenidae, and are related to the ioras and leafbirds. These are bulbul-like birds of open forest or thorn scrub, but whereas that group tends to be drab in colouration, fairy-bluebirds are sexually dimorphic, with the males being dark blue in plumage, and the females duller green.
Both species eat fruit, especially figs, and possibly some insects. They lay two to three eggs in a tree nest.
The call of the Asian fairy-bluebird is a liquid two note Glue-It.
As the names would suggest, the Asian fairy-bluebird occurs across southern Asia, and the Philippine fairy-bluebird in that archipelago. They are robust birds that resemble Old World orioles in shape and size. Males are larger than females, and the two species weigh between 50g & 100g, with some of that variation being caused by sexual differences and some by geographic variation. There are clines in size differences in both species which can be attributed to Bergmann’s rule, with the northernmost populations being larger on average. Both species have a powerful deep and notched bill used for crushing, with that of the Philippine species being larger. Their feet are small, which suggests that they spend less time climbing in order to feed and more time on the wing.
Their plumage is exceptional, with the upper-parts being deep rich blue. The Asian fairy-bluebird is sexually dimorphic in its plumage, with the male being much brighter than the female, but the Philippine fairy-bluebird exhibits much less difference and the female is almost as bright as the male. The deep colour is provided by specialised naked feather-tip barbs. Although the fairy-bluebirds are highly visible in sunlight they are much less visible in the shade of the forest.
They have a discontinuous distribution from India to Java and Vietnam. In India the species is present in the south west of the country and in the north east. From Burma it has a continuous distribution (in suitable habitat) throughout most of South East Asia, and down into Borneo and Sumatra, as well as on the Andaman Islands. The species has not been reliably recorded on Sri Lanka since the 1870s. The Philippine fairy-bluebird is found only on Luzon, Polillo, Leyte, Samar, Mindanao, Dinagat and Basilan.
They are dependent upon fruit producing forests, but both species seem to exist in a wide range of forests, both evergreen and semi-evergreen where they forage widely to obtain food.. Within forests they are usually found in the canopy. They generally eat fruit of a certain size, and will crush larger fruits in order to make them manageable. Most food is obtained in the canopy. In addition to fruit berries may be eaten, as well as nectar, although this behaviour has only been reported in birds in India. In contrast to adults, however, insects are the principal component of the diet of nestlings. In the Philippines birds have been observed following troops of macaques, possibly in order to collect flushed insects.
Male courtship displays include elaborate vocalisations, which the female responds to with nest building. Nests are constructed in trees or tall bushes from twigs, moss and grasses, and males and females cooperate in rearing chicks
There are just two species in this family of Fairy Bluebirds; they are:
Asian Fairy-bluebird Irena puella
Philippine Fairy-bluebird Irena cyanogaster
Number of bird species: 2