In the Kalahari Desert, South Africa, a native bird called the Sociable Weaver Bird constructs massive nests that, from a distance, looks like a giant haystack that's fallen into a tree. The foundation of these nests are often trees or a utility pole such as the ones that carry telephone wires. Over these the birds create a frame with larger sticks and then build walls from dry grasses to form individual rooms, and line each chamber of the nest with softer grasses and fibers. Sharp spikes of straw protect the entrance tunnels from predators. These nests are the largest built by any bird, and are large enough to house over a hundred pairs of birds. Some sociable weaver nests have remained occupied for several generations spanning over 100 years.
The nests are highly structured and provide birds with a more advantageous temperature relative to the outside. The central chambers retain heat and are used for nighttime roosting. The outer rooms are used for daytime shade and maintain temperatures of 7-8 degrees Celsius inside while outside temperatures may range from 16-33 degrees Celsius.
The birds acquired the name “sociable” not because they live in large colonies, but because they are known to share their nests with several other species including owls, vultures, eagles, red-headed finches, ashy tits, familiar chats, and many more. The weaver birds are more than willing to welcome the guests. More residents mean more eyes keeping a watch for danger. And the weavers often learn from the other birds where new sources of food can be found.