302 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1949 
The evidence does suggest that the nest-building habit is indulged in 
out of the breeding season and by nonbreeding birds; not too different 
from the typical weavers in this respect. 
The next subfamily, the sparrow weavers and social weavers (Ploce- 
passerinae), shows a great indulgence in nest building, in and out of 
the breeding time, which culminates in the truly gigantic communal 
structures of the social weaver (Philetairus socius). Thus, of one 
South African sparrow weaver, Plocepasser mahali, Roberts (1940, 
p. 332) writes that— 
. a single pair of birds will construct as many as a dozen nests of whitish grass 
stems on the projecting branches, these being arched over the top with two 
entrances below on opposite sides, so that there is no cavity for the eggs and 
evidently made for amusement only; the nests in which the eggs are laid have 
only one entrance and are warmly lined with feathery grass tops .. . 
A somewhat different description is given by Stark (1900, pp. 84-85) 
who informs us that the species is— 
. of social habits, it remains in flock all the year round and breeds in company, 
several nests being generally built in a single tree. Rarely have I met with more 
pugnacious birds; the males in spring are constantly fighting, and so desperate 
are their quarrels that the combatants frequently lie exhausted, side by side, on 
the ground, incapable for further movement ... The nests are large, roughly 
built, kidney-shaped structures, usually placed near the ends of the branches of a 
mimosa or other thorny tree. They are constructed of long grass-stems, the 
blades and flowering tops being woven together, the stiff stalks projecting in all 
directions. During the winter each nest has two entrances from below, separated 
in the interior by a narrow bridge of grass, on which the birds roost. At the 
beginning of the breeding season one entrance is stopped up with leaves and grass, 
a shallow cavity being left in which the female deposits two or three eggs... 
As soon as the young are on the wing, the second entrance is unstopped, and the 
nest is again used, both by the old and young birds, as a roosting place. The 
nests are annually repaired and last for many years. 
A somewhat similar account holds for another species, the gray- 
headed social weaver of East Africa, Pseudonigrita arnaudi. Jackson 
(p. 1384) comments on the remarkable nest of this bird— 
. . . it is very large and quite exceptionally compact, and has two entrances 
pointing downwards. During the period between breeding seasons these nests 
are used for roosting, the birds resting on the ridge between the two entrances. 
In the breeding season one of the holes is stopped up and the eggs are deposited 
in a depression beyond the ridge on the material used for stopping up the second 
entrance. The nest is firmly woven to several twigs or branches . . . in small 
clumps of five to eight nests together. 
Of a slightly different race of the same species Jackson found (p. 1385) 
the nests ‘‘. . . were packed together so closely as to form almost one 
compound nest.” 
Probably the most remarkable of all weaverbirds’ nests is that of 
the famous sociable weaver of the western arid portions of South 
Africa, Philetairus socius. The enormous communal nests built by 
