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.