182 BIRDS OF LA PLATA 
rule that each cock bird fi; only one hen, I have 
known several instances of a cock with two hens, 
the two females laying their eggs in one nest and 
taking turns in sitting on them. I have also found 
instances of two males to one female; and in one 
case where I watched the birds I noticed that when 
the female was on the nest the males stood over her, 
one on each side. 
I once had my attention drawn to a large concourse 
of Térus by the strange behaviour of two individuals 
amongst them, and I stayed to watch their proceed- 
ings. It was in the dry, hot weather, and a great 
many birds had congregated to drink at a lagoon. 
Some hundreds of them were standing about, quietly 
preening their feathers, and in the middle of the 
flock two birds were conspicuously marching about, 
stiff and upright as a couple of soldiers engaged in 
some military exercise, and uttering loud notes full 
of authority. Every few minutes a fresh bird would 
arrive and alight at some distance from the water, 
on which the two noisy birds would bustle up, and, 
ranging themselves behind it, run it with loud drum- 
ming notes to the margin; then, standing close 
together, they would wait till its thirst was quenched, 
after which they would run it away to some distance 
from the water, of which they seemed to have made 
themselves dispensers. For over an hour I continued 
watching them, and every bird that arrived was 
conducted to and from the water in this ceremonious 
manner. 
Occasionally several couples unite and soar about 
