Heat-shield mechanism, stringent security checks and expert craftsmanship… With summer fast approaching, Hema Vijay goes around the city to put together fascinating nuggets about the Baya weavers who get ready for the nesting season with their signature gourd-shaped hanging nests

Not many humans take the initiative to build ingeniously designed, cosy homes just to woo a mate and to house the to-be-born children, but our tiny Thookanaan kuruvi (Baya weaver bird) does it all the time. The male weaves amazing hanging nests that come with heat-shield mechanisms and security checks to stay out of reach of predators. The female inspects these nests midway during the construction, and she accepts the male’s advances only if she is satisfied with the nest and its location. Once this romantic bond is struck, the male goes on to complete the nest and the couple lives and breeds happily thereafter. When females reject nests, some male weavers have been spotted tearing up the nest in frustration, say birders.

Baya weavers begin nesting as summer approaches, and now is a good time to take in the ingenuity of this avian operation. So remarkable are the building techniques and nest-building rituals of the weaver bird that it is now referred upon as a management strategy. Apparently, zoo-musicologist A.J. Mithra was working on a book on the weaver bird’s nest-building expertise, before he passed away earlier this year.

Spotting weavers

To spot weaver birds, head to the city outskirts or green areas within the city with access to seed sources as food for the weavers. Look carefully at trees near open fields in suburban areas such as Tambaram, areas en route to Vedanthangal, etc. Zoom in on trees such as the palm, acacia and thorny varieties; and in recent times, on suspended cables too. Trees with branches hanging over water bodies are a good bet too, as these minimise access to predators. If you spot one nest, you are likely to spot several more, as weaver birds like to nest in groups. In fact, African sparrow weaver birds even build ‘nest apartments’, with 100 to 300 nests within the complex!

Normally, weaver birds sport a dull yellow colour with black markings and look like sparrows at a glance. “As breeding season approaches, the males grow brighter in colour, with the yellows and the black markings becoming more prominent,” says Preston Ahimaz, Nature and wildlife consultant.

Ingenious technique

Weaver birds’ nests look neat and well-finished, as if made by an expert craftsman, without straws sticking out. The nests have a definite design that includes a looped attachment to the branch, a roof, the egg chamber, antechamber and entrance tube. “These birds build instinctively. Even one-and-half-year-old weaver birds can be spotted building fantastic gourd-shaped hanging nests,” says K.V. Sudhakar, Madras Naturalists’ Society. The nest entrance is strategically located at the base and turned downwards, to avoid entry of predators. “The Baya weaver may also build a sunshade in the form of an overhanging projection,” informs Sudhakar. Showing incredible tenacity, Baya birds make hundreds of trips to get bits of plant fibre to create nests. “They build the nests over a few weeks’ time, and the nests are quite sturdy and last a few seasons,” says Vandana, avid birder.

So how does the weaver bird engineer such a complex shape? Apparently, the Baya uses its claw to keep the grass strand in place around the branch and loops the strand around the branch, and then knots it. It even makes reverse windings to strengthen it further. The weaver bird next extends the loop into a ring-shape by piercing strands into already formed loops, and proceeds to weave the nest into its characteristic shape.

“In the half-finished stage, when the nest looks like a tube with an open swollen pouch at its base, the male flaps its wings to catch the attention of passing females. If the female accepts the nest, the nest is completed by building the entrance tube,” says Preston. The nest turns is quite sturdy, about a centimetre thick in places. “It is waterproof too,” Preston informs. Imagine, the Baya creates this safe house purely by weaving, though mud might be found stuck on the inner surface of the nest at times.

The intelligence of the Baya weaver birds is said to have earlier prompted humans to train and use them as street performers. But watching them work and live their natural lives might be even more useful.