Sunday, October 29, 2000		Nature

These birds chime
By Nutan Shukla

BELONGING to the group of bellbirds, bellminers are confined to coastal eastern Australia and live in a ‘joint family system’ where every member helps the family in one way or the other. When chicks come out of the eggs they are fed by all the members of the family including the older brothers and sisters. It has also been observed that at times other birds, not belonging to the chicks’ group or family, also feed their neighbour’s children.

Not only that, when the chicks are still in the nest and are unable to defend themselves, the whole group remains cautious. Whenever danger threatens, adults perform special display which in most of the cases stops the intruder from proceeding towards the nest. As soon as any predator is spotted, the nearest bird will first crouch on the perch and at an appropriate moment it will suddenly raise its wings and flutter as if injured and then with a harsh mewing call drops to the ground where it will keep on fluttering and attracting the predator.

This falling stone display works well with the predators, like cats and goannas, who climb the tree to reach the nest. When they see a more obvious and helpless victim struggling on the ground, they will be tempted to come down from the tree, leaving the nest untouched. This is how the bird uses distraction display to its advantage.

In these birds, nesting may take place in any season and several broods can be reared in one year. Nest building, incubating and brooding is done by the female alone.

Also known as miner, they have gold-coloured bills and legs. It is believed that they have been given the common name miner to honour those explorers who searched for gold in the ground under the trees in which the birds lived.

About 20 cm in length, they have a bright yellow spot in front of the eye, besides the same coloured bill and legs. An olive green plumage gives them very effective camouflage among the tree leaves because of which they are more often heard than seen.

The name bellminer has probably been given to these birds because of their call which is a very distinctive feature of the bird. They make a single "ping" note, which sounds like small bell had been struck. Since these birds live in colonies and chime away constantly which means that there is never only a single note, instead the whole surrounding comes alive with the tinkling of a myriad of bells.

The above mentioned birds are members of a large group known as honeyeaters. They are known for their long, protruding tongue with a brush-like tip, which they use for extracting nectar from flowers and while doing so they inadvertently act as effective pollinators. It is believed that some species have co-evolved with certain species of plants.

These birds have a highly specialised tounge whose tip is deeply cleft into four parts which are delicately frayed on the edges. This forms the so-called brush. These birds, while extracting nectar, extend their tongue to it and the liquid drawn up by capillary action. when the tongue is withdrawn the mouth is closed and inside the beak tongue is compressed by the projections on the roof of the beak thus forcing the nectar or any other liquid out of the brush along the two grooves at the base of the tongue leading to the throat. The whole process takes very little time, this can well be imagined by the fact that while feeding bird inserts its tongue inside the flower at the rate of about ten times per second.