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April 20, 2012

Animal Pioneering: Masked Weaver's Nest

copyright Chris Eason
Masked Weavers are very common birds in South Africa, building their unusual woven nests in summer. A male will build many nests and attract a female to lay eggs in each one. I have seen clusters of up to ten nests built by one male. But these finches don't start out as master builders. In their first year, male weaver build their nests in the wrong place, or (like tenderfoot Scouts) get their knots wrong and the nests fall out their trees before they have a chance to attract a tenant.

A first year weaver started building a nest in my garden recently - about 1,5m (5 feet) off the ground. He abandoned his construction - the nest was far too close to the ground to be safe from predators - but left this starting knot. If you look closely you'll see a loose series of half hitches and windings, twisting and braiding back over each other. Weavers do generally start their knots at a fork in a branch as well, to give the nest a better anchoring point.

Here is the next step in the process, the initial 'ring' that the weaver then perches on to do the rest of the weaving.

This drawing from page 212 of the book
Animal Architects (ebook) shows the sequence most weaverbirds follow to construct their nests: After the establishing knot, they tie a ring which they perch on while they build the roof, egg chamber and entrance, finally lining the nest in preparation for an egg to be laid.

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