Grey-capped social weaver

Based on recent DNA-analysis (which did not include P. cabanisi), the genus Pseudonigrita belongs to the group of sparrow weavers (subfamily Plocepasserinae), and is most related to Philetairus socius. This clade is sister to Plocepasser.[6] Provided that the sister relationship between the Pseudonigrita-species is correct, the following tree expresses current insights.

Eggs are laid throughout the year, but there is a peak that enables the birds to make use of periods that food is plenty, such as between August and December in South Sudan and between March and May in eastern Africa. Three or four eggs are laid in a roofed nest, that is suspended from a thin branch an in ant-gall acacia (Acacia drepanolobium), or another spined and ant-housing acacia. The nest consists of grass straws, and during breeding and feeding the nestlings has one downward-facing opening. Eggs are approximately 19 mm long and 14 mm in diameter, greenish, bluish or white, unadorned or with fine black or olive colored specks, more dense at thick end, or so heavily blotched that the overall color seems olive-brown or ash-grey. Both parents share breeding duty but the female about twice as often as the male, until after thirteen or fourteen days, the eggs hatch.[4]

The birds make long series of seven to ten high-pitched piercing squeaks, sounding like tseeer-tseeer-tseeer-....[7][12]

The grey-capped social weaver feeds on both grass seeds and insects, such as grasshoppers, beetles, termites and caterpillars. Feeding mostly takes place in groups at some distance from the colony.[7]

In P. arnaudi, nests are not only used for breeding and to protect the chicks, but also for fully grown birds to sleep at night. The species builds roofed nest in thorny Acacia trees and forms colonies. One of the two entrances is closed however just before eggs are laid and opened again around the moment of fledging. Male and female share incubation duties. Adult and adolescent birds from previous broods often help in nest building and feeding the chicks. The nestlings are initially fed on a diet consisting exclusively of insects, and grass seeds are only given during the last days. Fledging occurs after about twenty days.[8][10][11]

Nests are built hanging from thin branches, often in Vachellia drepanolobium, sometimes in other acacia species such as umbrella thorn acacia (V. tortilis), blackthorn (Senegalia mellifera) or gum acacia (S. senegal). The nests have thick walls. These are constructed from grass straws, which, in the dry climates where P. arnaudi is found, keep well for many months. Nest are often constructed with two or three side-to-side or under old nests.[4][10][11]

In Kenya, some individuals rested in their nests year round, also outside the breeding periods, with two to five together. The immediate surroundings of the nests were generally not defended against birds from other families that nest or sleep in the same Acacia tree that houses the colony. However, birds from other trees were usually attacked when landing in the colony tree. The order in which birds are allowed to feed is according to dominance, although members from other families from the same colony where better tolerated than birds from other colonies. Aggression was rare or absent between members of the same group. The behavior of the grey-capped social weaver closely resembles that of the sociable weaver Philetairus socius.[10][11]

Roofed nests, with two downward-facing nest entrances, colony nesting, and choosing a thorny nesting tree, are all considered adaptations that help limit predation. Aggregated nests, thick walls and communal sleeping are considered adaptations against the cold nights in the arid distribution area of P. arnaudi.[11]

Chestnut sparrows (Passer eminibey) sometimes drive grey-capped social weavers from their nests to take them over. Cut-throat finches (Amadina fasciata) however only use deserted nests.[4]