Let's Talk About Birds: Gold-medal nest builders

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This is one of a series presented by the National Aviary, which works to inspire respect for nature through an appreciation of birds.
Gold-medal nest builders

If nest building were an Olympic event, then surely the East African team of Taveta golden weavers (currently "training" in the Tropical Forest room at the National Aviary) would be favored to win gold in the hundred-nest dash.

Ever since they were moved into the lush and spacious Tropical Forest exhibit from the confines of the Aviary's old Desert exhibit (where their nest-building obsession was limited by the amount of available nest-building material and suitable attachment sites), they have begun building nests left and right. In nature, Taveta golden weavers prefer to build their nests on thin branches hanging over water, which provides protection from predators. The Tropical Forest, with its flowing stream on one side and pond on the other, is an ideal habitat for them.

From start to finish, an industrious weaver can build a nest in as little as one day, but a few days is more usual. This includes tearing and cutting hundreds of strips of cycad and palm leaves to the right thickness and length for every stage of the weaving process. The strands are stitched together very tightly, using intricate loops and knots, and the finished nest is about the size of a softball with an opening on the side or bottom. Like all birds, weavers are born "knowing" how to construct the nest that is typical of their species. Even though their weaving and knot-tying skills can improve with practice, male weavers have an innate genetic blueprint for building their intricately woven nests.

When a male has finished a nest, he may hang upside down from the entrance hole, calling and waving his bright yellow wings to "advertise" his "open house" to females searching for a mate who can provide her with a safe place to lay her eggs. Females seem to prefer "fresh" nests made of supple green plant material, so males continually add new "grass" to the outside of their nests. Because females also are choosy about the location of nests, males usually build more than one. In our exhibit, five males are vying for the attention of four females, which has led to 11 nests being built in just the past few weeks.

If Taveta golden weavers are nimble nest-building gym-nests, then our Hammerkop is the Olympic weight-lifter in our Tropical Forest exhibit. This crow-sized member of the stork family builds the largest domed nest of any bird in the world -- as much as four feet wide and five feet high and built out of thousands of large sticks and heavy clumps of mud and grass.

Of all the things that fascinate us about birds, such as their flight ability and their songs, perhaps nothing is more amazing to us than the care and skill they show in building homes for themselves and their young. Although the nesting season for most of our wild birds is ending, you can always find nesting birds when you visit the National Aviary.



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