Environment

Do baya weavers spin the roulette for a nesting tree?

A colony of baya weaver nests on a lone palm tree at Ottiyambakkam on Karanai Main Road, on September 22, 2021. Photos: Prince Frederick   

In Ottiyambakkam, on Karanai Main Road stands a lone palm tree bent down with the efforts and expectations of male baya weavers. The choice of this tree for a colony of nests suggests whimsicality, causing one to wonder if baya weavers live by the roulette.

While a legion of lakes in the region, watched over by palm trees that stand on their bunds like towering sentinels wilt under rejection by the baya weavers (Periya Eri in Siruseri with its arresting palm plantation clearly among the jilted), this palm tree is puffed up with pride. Imagine the good luck of a villa-based gated community situated diametrically opposite this tree. However one wonders how many residents would have noticed it, let alone recognised their fortune. Getting to the overwhelming question at hand, did the baya weavers veer away from the "rule book" of nesting site selection? If so, how much?

If one expected a copy-book approach, the baya weavers should have chosen a palm or any other tree that stands with the heels resting on the edge of a waterbody. It is a device to insulate the eggs and later the nestlings against predation. A tree that leans like a tower of Pisa into a waterbody can raise questions in a creature out for a bite.

Adding another layer of safety against predators would have meant that the mantle fell on a thorny tree in this attitude of penance.

A colony of baya weaver nests on a lone palm tree at Ottiyambakkam on Karanai Main Road, on September 22, 2021. Photo: Prince Frederick 

A colony of baya weaver nests on a lone palm tree at Ottiyambakkam on Karanai Main Road, on September 22, 2021. Photo: Prince Frederick   

This palm tree is parked a cricket pitch distance away from a waterbody.

When this writer shared this sighting and the questions around it, ornithologist V Santharam said the birds would have plumped for this tree, weighing three key concerns. One of the three uncovers the bane of pilferage in the life of the industrious and gallant male baya weaver. “The male baya weaver collects 500 to 600 different strands of grass to craft a nest. To collect the nest material, it has to head out often, and if these trips are long, there is the risk of pilferage by a neighbour. So, the choice of a tree for a nesting colony would be partly dictated by quick access to nest material,” explains Santharam.

“Another major consideration — probably the most important — is the availability of food. The adult baya weaver eats all kinds of seeds with its beak specifically designed for cracking open hard seeds. However, the nestlings need to be fed the larvae of caterpillars. The choice of nesting site would factor in these considerations.”

Besides, there is the factor of “history”, says Santharam.

“A nesting tree along with others would have been traditionally used for community nesting. While other trees would have gone, a lone tree may be around, and the baya weavers prolong the tradition with this survivor.”

(Field Notes is a column about the resident and migratory birds of Chennai)


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Printable version | Oct 25, 2021 6:40:55 AM | https://www.thehindu.com/sci-tech/energy-and-environment/do-baya-weavers-spin-the-roulette-for-a-nesting-tree/article36674230.ece

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