Class: Aves (Birds)
Body length: 5.5 inches (14 centimeters)
Weight: 0.9 to 1.06 ounces (26 to 30 grams)
Life span: (not known)
Incubation: 12 to14 days
Number of eggs laid: 2 to 6
Weight at hatching: approximately 0.07 ounces (2 grams)
Age of maturity: fledge at 14 to 16 days, mature plumage at 16 to 18 weeks
Conservation status: stable
• Sociable weavers may seem like clever artisans with their nest-building
ability. But the birds build or add to their nest instinctively—they
don't need training and can only create their dwelling place the
same way their ancestors have done.
• The largest sociable weaver nests are over 20 feet (6 meters) wide and close to 10 feet (3 meters) tall with more than 100 individual nesting chambers. Some weigh several tons and can get so heavy they knock down the supporting tree.
• Record holder: the sociable weaver is the builder of the largest tree nests in the world.
Birds: Sociable Weavers
Weaver world wonders
The sociable weaver is a very common little brown bird in the Kalahari region of southern Africa. However, this sparrow-sized critter may quite possibly be one of the most interesting birds in the world! Sociable weavers are unlike most other birds due to their lifestyle and nest building: they weave one nest for their entire colony as well as for future residents. This is no ordinary nest—it is massive, like a giant apartment block occupied by up to 100 sociable weaver families all year long. Some sociable weaver nests have remained occupied for over 100 years!
From a distance, the sociable weaver nest may resemble a haystack hanging in a tree. But if you crawl under the nest and look up you will see the entrances to the different chambers within the nest–sort of like a bee's honeycomb. Nest entrance tunnels can be up to 10 inches (25 centimeters) long and 3 inches (7 centimeters) wide. Round, cozy nesting chambers are usually 4 to 6 inches (10 to 15 centimeters) in diameter. There may be 5 to 100 nesting chambers in a single sociable weaver nest, providing a home for 10 to 400 birds!
Photo by Kenneth Fink
Making a home for all
When building the nest, sociable weavers use different materials for different purposes. Large twigs form the roof of the nest, dry grasses create the separate chambers, and sharp spikes of straw protect the entrance tunnels from predators. Nesting chambers are lined from top to bottom with soft plant material, fur, cotton, and fluff. A proper nesting tree should have a long, smooth trunk and high branches to discourage slithering predators such as Cape cobras and boomslangs, a type of tree snake. For some sociable weavers in Africa, the perfect nest-building tree has become a utility or telephone pole.
Weaver nests need constant care because of the nature of the materials used. Weavers have to continually add more material to keep the nest intact.
A climate-controlled nest
Large nests help the sociable weavers stay comfortable in the harsh climate of the Kalahari Desert. During freezing winter nights a move to the nest’s well-insulated center chambers helps the little birds stay warm. Scorching summer temperatures are easier to weather when roosting in one of the outer chambers of the nest.
My house is your house
The sociable weaver’s nest sees plenty of guests—a regular Kalahari Desert inn! The South African pygmy falcon Polihierax semitorquatus relies completely on the sociable weavers’ nest for its own home, often nesting side by side with the sociable weavers. The pied barbet, familiar chat, red-headed finch, ashy tit, and rosy-faced lovebird often find comfort in the cozy nesting chambers, too. Vultures, owls, and eagles will roost on the nests’ broad roof. Why are weavers willing to share the huge nest they worked so hard to make? 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.
Bugs on the menu
Sociable weavers need less water than any other bird. Most never take a drink, getting all the moisture they need from their food: bugs. Insects make up 80 percent of their diet, and the juicy harvester termites are a favorite. The rest of their diet is made up of seeds. At the San Diego Zoo, the weavers are offered crickets, fly and mealworm larva, finch seed, tropical fruit, and chopped greens.
All in the family
With so much family under one well-thatched roof, mom and dad have lots of helpers for the new chicks. Juvenile sociable weavers will provide food for their younger brothers and sisters. Parents will even provide insects for their neighbors’ young. And can you imagine never moving away from home? Sociable weavers do not migrate; in fact, chicks may never leave the nest. Fledgling chicks might just move to an empty nesting chamber nearby.
The San Diego Zoo is home to the only colony of sociable weavers in the United States. These busy builders are supplied with dry grasses each day so that they may tirelessly grow their nests. Always in motion, always together, the sociable weavers are an inspiration to see.