Isn't it amazing how much detail and beauty there is in the eyebrows and the head feathers of this little bird, which must to many people be the epitome of the LBJ?
The night photo and this one were taken near the Boegoeberg dam.
Peter Connan wrote:Isn't it amazing how much detail and beauty there is in the eyebrows and the head feathers of this little bird, which must to many people be the epitome of the LBJ?
Couldn't agree more and your photos, particularly the last one, stress that perfectly.
God put me on earth to accomplish a certain amount of things. Right now I'm so far behind that I'll never die.
Even without gaudy colours, this little bird has lots of character
"Education is the most powerful weapon which you can use to change the world." Nelson Mandela The desire for equality must never exceed the demands of knowledge
Leighton GM, Meiden LV (2016) Sociable Weavers Increase Cooperative Nest Construction after Suffering Aggression. PLoS ONE 11(3): e0150953. doi:10.1371/journal.pone.0150953 http://journals.plos.org/plosone/articl ... ne.0150953
Abstract
The major transitions in evolution rely on the formation of stable groups that are composed of previously independent units, and the stability of these groups requires both cooperation and reduced conflict. Conflict over group resources may be common, as suggested by work in both cichlids and humans that has investigated how societies resolve conflict regarding investment in group resources, i.e. public goods. We investigated whether sociable weavers (Philetairus socius) use aggressive behaviors to modulate the cooperative behavior of group mates. We find that the individuals that build the communal thatch of the nest, i.e. the individuals most at risk of exploitation, are the most aggressive individuals. We show that individuals that invest in interior chamber maintenance, possibly a more selfish behavior, suffer relatively more aggression. After suffering aggression individuals significantly increase cooperative construction of the communal nest thatch. We show that cooperative individuals target aggression towards selfish individuals, and the individuals suffering aggression perform cooperative behaviors subsequent to suffering aggression. In addition to other evolutionary mechanisms, these results suggest that aggression, possibly via the pay-to-stay mechanism, is possibly being used to maintain a public good.
Don't come and tell me that the instincts of animals are very different from the human ones, only on another level
"Education is the most powerful weapon which you can use to change the world." Nelson Mandela The desire for equality must never exceed the demands of knowledge
Identification
Measuring around 14 cm in length, the Sociable Weaver has a black chin, black barred flanks and a scalloped back. It weighs between 26 and 32 grams and sexes are indistinguishable.
Conservation status
Least concern.
Habitat and Distribution
The Sociable Weaver’s range is centred within the Northern Cape Province of South Africa, and it isstrongly associated with the arid savannahs characteristic of the southern Kalahari region.
Breeding
Sociable Weavers build large compound community nests, a rarity among birds. These nests are perhaps the most spectacular structures built by any bird. The communal nest mass contains multiple independent nest chambers that are used for roosting throughout the year and for breeding. These weavers are cooperative breeders, with up to five (or sometimes more) ‘helpers’ assisting the breeding pair by bringing additional food to the young in the nest.
Sociable Weavers breed in response to rainfall, so the length of the breeding season varies from year to year. Females usually lay 3-4 eggs in a clutch, and can lay successive clutches, as long as the breeding conditions remain favourable. A maximum of 15 clutches was recorded in a 10 month-long breeding season, as a result of continuous predation by snakes. The oldest recorded adult was 16 years old.
Relationships with other species
In an ecological sense, Sociable Weavers are more than just birds, they are ecosystem engineers. Colonies cooperate to build the largest nests of any bird in the world. These iconic structures provide shelter for not only the weavers themselves, but many other species of small birds, including Black-cheeked Waxbills, Acacia Pied Barbets and others that can be found roosting in the nest chambers at night.
The Pygmy Falcon has a near-obligate relationship with the weavers, existing only where there is a nest to support it. The weavers seem to tolerate the falcons, despite losing the odd chick to their lodgers – but the true nature of the relationship remains to be unravelled. New research also suggests that a suite of other unexpected species, such as the Kalahari tree skink, may be more abundant in camelthorn trees that host weaver nests.
Sociable Weavers also have a close, if unfriendly, relationship with Cape Cobras and other snakes. The golden loops of a cobra raiding a Sociable Weaver nest is one of the enduring images of the Kalahari, combining both beauty and horror. Sociable Weavers are energetic, even frenetic, and do everything together. The distinctive flight call emanating from hundreds of birds, and the rush of wings as a flock barrels by, is an experience not to be forgotten.
Food
The Sociable Weaver is insectivorous, with insects comprising 80% of their diet. As an adaptation to living in the dry Kalahari Desert, where water is scarce, they obtain their water from the insects they feed on, although they will also drink water from stock troughs and farm dams when it is available. They also feed on seeds and other
plant products, foraging predominantly on the ground, but also on bark and leaves of trees.
Interaction with humans, distribution changes and expected changes
In spite of living in such a challenging environment, Sociable Weavers are one of the most common species wherever they occur. With the recent availability of man-made structures like telephone and electricity poles, the weavers have even expanded their distribution range to some areas of the northern Nama-Karoo, where they couldn’t nest in the past due to the lack of trees. It has been speculated that this expansion may be facilitated by reduced nest predation by snakes in these areas – given the difficulty of climbing the smooth, upright poles – thereby freeing the weavers from one of their main causes of breeding failure. However, other human activities may yet affect the weavers in other unpredictable ways.
Sociable Weaver – a weaver world wonder
The Sociable Weaver is a little brown bird, yet this sparrow-sized LBJ may be one of the most interesting birds in the world! Sociable Weavers are unlike most other birds due to the way they go about nest building. They weave one nest for their entire colony.
Not your average nest
This is no ordinary nest—it is massive. From a distance, the Sociable Weaver nest may resemble a haystack hanging in a tree. But if you walk under the nest and look up, you can see the entrances to the different chambers within the nest. Nesting chambers are 10 to 15 cm in diameter.
There may be up to 180 nesting chambers in a single Sociable Weaver nest, providing a home for anything up to 400 - 500 birds!
In an ecological sense, Sociable Weavers are more than just birds, they are ecosystem engineers. Colonies cooperate to build the largest nests of any bird in the world. These iconic structures provide shelter for not only the weavers themselves, but many other species of small birds, including Black-cheeked Waxbills, Acacia Pied Barbets and others that can be found roosting in the nest chambers at night.
A climate-controlled nest
Large nests help the Sociable Weavers stay comfortable in the harsh climate of the Kalahari. Centre chambers – and deeper chambers – are buffered from climate
extremes, be these cool or hot extremes. 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.
Social structure and Cooperation
The aptly named Sociable Weaver has a truly fascinating social structure. The nuclear family, composed of a breeding pair and their young, stay together throughout the whole year and into the following breeding season (or sometimes longer), roosting every night in the family chamber. Above the family unit, the neighbourhood often includes relatives living nearby (though not exclusively so). And if a snake threatens a nest, the close relatives and neighbours are more likely to mob it than birds from another part of the colony!
Finally, all these different families and neighbourhoods come together, and the whole colony moves around as a cohesive group when the birds forage.
As in any functioning society, Sociable Weavers also cooperate on multiple tasks: grown-up young help their families raising chicks and cleaning the nest, everyone participates in nest building and maintenance and, of course, all watch for predators and warn their mates if danger approaches.
