The sociable weaver Philetairus socius is a colonial and highly social bird endemic to southern Africa, occurring in the arid savannahs associated with the Kalahari biome, from northern Namibia to north-central South Africa.
They usually start breeding at the end of winter, but their breeding activity is closely linked to rainfall and they can carry on breeding for 8-10 months or longer, leading to year-round breeding (recorded once in our population). This means that a single female will lay a very high number of clutches in a single season. We have recorded several cases where more than 10 clutches where laid by a single female within one breeding season.
The clutches usually vary between 2-4 eggs, but when the conditions are very good, clutches of 5 or even 6 eggs can be produced (clutches of one egg are also possible under poor conditions, though that is rare). The incubation period is typically 15 days and the nestling period 21-24 days
Sociable weavers are cooperative breeders, which means that they have helpers at the nest. These are non-breeding adults that assist raising the chicks and looking after the nest (contributing to cleaning, nest maintenance and defence). The helpers are usually offspring from previous broods, but can be more distant relatives (such as uncles or cousins) and even unrelated birds may sometimes help.
In our population, the presence of helpers is associated with improved reproductive success, and this effect is more noticeable under adverse conditions (such as low rainfall or higher temperatures). However, under whether extremes, such as hot spells, reproduction is badly affected, whether or not there are helpers at the nest, a worrying sign given the global climate crisis.
These weavers cooperate in other tasks, the most impressive being the communal nest building, which allows their massive nest structure to be built and maintained for several decades. They also cooperate to watch out for predators and to mob them. For example, they can mob snakes, which are their main nest predator (in particular boomslangs Dispholidus typus and Cape cobras Naja Nivea), and pygmy falcons Polihierax semitorquatus), which use the sociable weaver nest chambers for reproduction and roosting, but may sometimes predate on the nestlings and fledglings.