114 BIRDS OF LA PLATA 
but whether in such cases the birds are paired or 
practise a promiscuous intercourse I have not been 
able to discover. They have a great partiality for the 
large domed nests made by the Anumbius acuti- 
caudatus, called Firewood-Gatherer in the vernacular. 
One summer a flock of about ten Bay-wings took 
possession of a nest on one of my trees, and after a 
few days I took fourteen eggs from it. Though the 
birds hopped chirping around me, manifesting great 
solicitude, the eggs were quite cold, and had I left 
them many more would have been laid, no doubt ; 
but as they were piled up three or four deep in the 
nest they could never have been hatched. 
As a rule, however, the flock breaks up into pairs ; 
and then a neat, well-made nest is built in the fork 
of a branch, lined with horsehair ; or, oftener still, 
a domed nest is seized, the Bay-wings fighting with 
great spirit to get possession, and in it, or on it, their 
own nest is made. Like their relation, the Common 
Cow-bird, they seem strongly attracted by domed 
nests, and yet shrink from laying in the dark interior ; 
as a rule when they have captured a large domed 
nest they break a hole in the side and so admit the 
light and form an easy entrance. 
The eggs of the Bay-wing are five in number, 
nearly round, and densely marked with dusky reddish 
brown. 
