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 Post subject: White-browed Bulbul: Common and voluble but shy
 Post Posted: Wed Sep 07, 2005 1:25 am 
White-browed Bulbul: Common and voluble but shy

By Jagath Gunewardena
@ The Island

Bulbuls are medium-sized birds with short, round wings, medium or long tails, short sturdy legs and soft plumage. They are arboreal in habit and feed mainly on fruit. They belong to the family Pycnonotidae that is represented by six species in Sri Lanka. Two of them, the Red-vented Bulbul and the White-browed Bulbul are familiar to many, being common and widespread birds that are often met with near human habitations.

The White-browed Bulbul [Pycnonotus luteolus insulae] is 20 cm. [8 inches] long and has a long tail and a full plumaged body. The upper parts are a drab olive green colour. The face has an elaborate pattern that makes identification easy. A thin black line from the beak runs through the eye to the back of the head, topped by a broad prominent white brow [or supercilium] and a crescent shaped white patch cupping the eye from below. A thin black moustache stripe goes to the back of the head. Several thin black lines can be seen on the light brown or greyish ear-coverts. The chin and a small patch behind the beak are light yellow. The greyish or greenish-grey breast pales into a dirty white or yellowish white in the abdomen. The undertail coverts are a bright light yellow. The beak is black and the legs are black or grey. The eyes are deep dull red or blood red. Males and females are similar in colouration. The drab colouration has earned it the Sinhala name Guru-Kondaya, although it does not have a crest characteristic of many members of this family.

An active bird that usually lives as pairs, it moves from branch to branch and from tree to tree, often making loud calls. It is a bird that likes low trees and shrubs, but does not descend to the ground. It

is somewhat shy and retiring, preferring to spend much of the time hidden among leafy branches that provide it with enough shelter, and comes out only for short periods. At times, a pair will ascend to the highest branches of a tree or to telephone or power cables but will not stay exposed for long. It is a noisy bird whose presence is often made known by the loud cells. The mostly uttered cell is a loud bubbling noise similar to air being blown into water through a straw. The Sinhala name Guluguduwa refers to this particular cell. Another is a loud chrr-chrr which is more of an alarm cell. There are several other loud cells uttered at times.

Its food consist mainly of fruits and it distinctly prefers small berries, such as Lantana, Coffee. Katu-pila, Cinnamon and Eraminie that can be swallowed whole. At times, it feeds on soft ripe fruits like papaw. It continues to feed throughout the day. It has the habit of sipping the nectar of large flowers such as Erabadu, Katuru-murunga and plantains. In homegardens, they lose much of the shyness and can be approached chosely if not frightened by sudden movement. The white-browed Bulbul is peaceful, unlike the Red-vented Bulbul which is quite aggressive. Each pair seems to have a loose territory, but were never seen chasing away another.

The breeding season is from December to June, but occasional nests are found during the other months. The nest is a neat little cup, loosely constructed with thin twigs on a fork of a branch, often about 1 to 3 meters above ground level. Both birds take part in the construction of the nest, incubation of eggs, feeding and tending of young. The eggs number two or three, white or pinkish in colour with red-brown markings. Although adults feed mainly on ripe fruits, young birds are fed exclusively on a diet of small, soft-bodied creatures, such as insects and spiders picked off the branches but are predated also by, snakes and Koels. It is possible that a pair may nest more than once during the season.

The white-browed Bulbul inhabits open scrubland and is found throughout the low country Wet and Dry Zones, and in the hills upto 1000 meters and even higher in the Uva Province. It is described in literature as one of the commonest birds in Sri Lanka. It has always been more common in the Dry Zone, which has more areas of habitat than the Wet Zone. The numbers and the range of distribution has steadily increased during the past two decades in many Wet Zone areas. It does not go into forests but prefers the borders. The clearing and degradation of many Wet Zone forests has provided more scrubland for it. It also tends to avoid human habitation with lots of tall trees, preferring areas with shrubs and open spaces. Our neighbourhood in Nugegoda with a lot of tall trees never had any resident white-browed Bulbuls. A pair was seen visiting the area during the previous two months occasionally but never stayed for long, departing always in a few minutes. In contrast, the eastern parts of the town and the Kotte Sanctuary which has large open areas have a fairly large population. This kind of local differences in distribution was seen in several other places.

The habit of gulping down small fruit with seeds and later defecating the seeds at other places helps in the distribution of such plants. Several alien invasive plants which bear edible fruits are helped to spread by the White-browed Bulbul. The alien shrub Lantana Camera [Gandapana in Sinhala] provides a lot of small berries that turn black when ripe and are very much favoured by this bird. The shrubs in addition provide the ideal type of habitat for it. The Lantana shrub is a troublesome invasive in many areas of Wet and Dry Zones. The Hairy Clidemia [Clidemia hirta] is another invasive that is spreading in the Wet Zone, both in forests and open areas. This shrub produces large, numbers of small berries that turn black when ripe and is eagerly consumed by this bird. The third invasive favoured by the White-browed Bulbul is the Chinese Guava [Psidium Catteleianum] that produces bunches of small fruit that turn yellow when ripe and is found in Colombo, Kalutara and Ratnapura Districts. The fruit becomes soft when ripe and is gulped down by this bird and excretes the hard seeds. Although this bird feeds on the fruits of the invasive Annona Glabra, it does not help in its dispersal.

The white-browed Bulbul is found only in India and Sri Lanka. The farm found in Sri Lanka, Pluteolus insulae was named by late Hugh Whistler in 1932 and is considered as an endemic sub-species. However in his Avifaunal Survey [1944] he claimed that he doubts the validity of the sub-species and that further research may show that two races occur in the country, and that specimens collected from Uragaha had been darker than others. He had stated that it is sufficient to draw attention to the problem for the moment. Hugh Whistler died in 1942, before the survey report was even published and it seems that no more attention was given to it, since.

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