Red-vented Bulbul - Behaviour and Ecology

Behaviour and Ecology

Red-vented bulbuls feed on fruits, petals of flowers, nectar, insects and occasionally geckos. They have also been seen feeding on the leaves of Medicago sativa.

Red-vented bulbuls build their nests in bushes at a height of around 2–3 m (7–10 ft; two or three eggs is a typical clutch. Nests are occasionally built inside houses or in a hole in a mud bank. In one instance, a nest was found on a floating mat of Water hyacinth leaves and another observer noted a pair nesting inside a regularly used bus. Nests in tree cavities have also been noted.

They breed from June to September. The eggs are pale-pinkish with spots of darker red more dense at the broad end. They are capable of having multiple clutches in a year. Nests are small flat cups made of small twigs but sometimes making use of metal wires. The eggs hatch after about 14 days. Both parents feed the chicks and on feeding trips wait for the young to excrete, swallowing the faecal sacs produced. The Pied Crested Cuckoo is a brood parasite of this species. Fires, heavy rains and predators are the main causes of fledgeling mortality in scrub habitats in southern India.

Their vocalizations are usually stereotyped and they call throughout the year. However a number of distinct call types have been identified including roosting, begging, greeting, flight and two kinds of alarm calls.

They are important dispersers of seed of plants such as Carissa spinarum.

The Red-vented Bulbul was among the first animals other than humans that was found to be incapable of synthesizing vitamin C. However a large number of birds were later found to likewise lack the ability to synthesize vitamin C.

Like most birds, these bulbuls are hosts to coccidian blood parasites (Isospora sp.) while some bird lice such as Menacanthus guldum (Ansari 1951 Proc. Natl. Inst. Sci. India 17:40) have been described as ectoparasites.

Along with Red-whiskered Bulbuls this species has led to changes in the population dynamics of butterfly morphs on the island of Oahu in Hawaii. Here the population of white morphs of the Danaus plexippus butterfly have risen over a period of 20 years due to predation of the orange morphs by these bulbuls.