THE WHITEHEAD 77 
three nests under the camera and the two broods 
brought down from tops of isolated trees or tree- 
groups, there were innumerable cases of families 
which we believed also were fed by four old birds. 
Although, however, in the vast majority of 
cases a Whitehead’s nest is run by a quartette, 
there do seem to occur cases where a pair may 
own a nest. One such, containing eggs, I watched 
for many days without seeing the slightest indi- 
cation of ownership by more than two birds. I 
believe, moreover, that in manipulation of the 
nest for purposes of photography, I had done 
enough to excite apprehension, and to bring into 
view owners number three and four had they 
existed. On the other hand, there were eggs 
only in the nest, always estimated at a lesser 
value than young. The third and fourth birds 
may therefore not have been sufficiently con- 
cerned to show themselves. Again, what I viewed 
as interchange of duty between birds one and 
two may have been interchange of duty between 
birds one and three, or between two and three 
and two and four, and so on. Be that as it may, 
the vast proportion of Whiteheads’ nests are 
administered by four birds, not two birds. 
We never came across a family of more than 
three. Three was the number of youngsters 
photographed in the nests run by groups of four 
old birds. Three likewise was the number of 
