BREEDING HABITS OF WEAVERBIRDS—FRIEDMANN 303 
these little sparrowlike birds attain truly great proportions—as much 
as 25 feet long and 15 feet wide at the base and from 5 to 10 feet in 
height! While each nest is the product of not a lone individual, or 
even a pair, but of a whole flock of as many as 75 or 80 pairs, still the 
sheer bulk of the nesting material gathered and placed by the birds 
is a striking testimony to the tremendous year-round urge of the nest- 
building instinct in this species. The time I spent studying this bird 
in the western Transvaal in 1925 was one of the most fascinating 
experiences an ornithologist could have, and I cannot refrain from 
including here part of my notes, at the expense of repeating some items 
already published in an earlier paper (1930). 
As the common name of the bird implies, Philetfairus is very social 
in its habits; in fact it is probably as social as any bird could possibly 
be. It is always found in flocks, feeds in flocks, and breeds in large, 
many-apartmented compound nests. The smallest flocks that I saw 
contained about 20 birds; the largest one at least 150. The flocks 
seem to stay pretty much in the same general vicinity all the year 
round, and the birds use their huge, massive nests as roosting places 
during the nonbreeding season. With this extreme sociability and 
sedentary habit of life the territorial relations of the species have-been 
modified in a way that is quite remarkable, perhaps unique among 
birds. Instead of each pair of birds having its own breeding territory, 
each flock seems to have a definite territory, and as the individual 
flocks are usually far enough apart not to compete with each other, 
the boundaries of these territories are seldom crossed by individuals 
of other flocks and other territories. However, in a few cases in my 
own experience two flocks were fairly close together (i. e., two nests 
were on trees not very far apart), and the birds mingled more or less 
while feeding, but in these cases far more fighting and quarreling was 
observed than in all the others together. In an area approximately 
100 miles long and 10 miles wide, or 1,000 square miles in all, I found 
only 26 nests of the social weaver, so it can be seen that the flocks 
ordinarily do not live in very close juxtaposition to each other. (The 
nests are so large, and so conspicuous at great distances, and the 
country so open and easy to examine, the trees being so relatively few 
in number, that I am quite certain I found practically every nest in 
this area.) 
The nests observed varied in size as did the flocks. The smallest 
nest found measured about 3 feet in diameter at the base and was 
about 3 feet high and had about 10 entrances on the under surface, 
indicating that it contained that number of individual nests. The 
largest one found was incomplete, i. e., a piece of it had broken off, 
breaking its supporting branches by its weight, but the remaining 
part was a large, flat, horizontal mass of straw, more or less repaired 
at its broken edge, and measured about 25 by 15 feet at the base and 
