92 BIRDS OF LA PLATA 
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COCOI HERON 
Ardea cocoi 
Above grey; head, wings, and tail slatey black; beneath white ; 
neck and sides striped with black ; length 36 inches, wing 18 inches, 
tail 7 inches. Sexes alike. 
Tuts fine Heron is found throughout South and 
some parts of North America. In size, form, and 
colour it closely resembles the Common Heron of 
Europe; in flight, language, and feeding-habits the 
two species are identical, albeit inhabiting regions 
so widely separated. In the southern part of South 
America it is not seen associating with its fellows, 
nor does it breed in heronries; but this may be 
owing to the circumstance that in the temperate 
countries it is very thinly distributed; and it is 
highly probable, I think, that in the hotter regions, 
where it is more abundant, its habits may not appear 
so unsocial. Though they are always seen fishing 
singly, they pair for life, and male and female are 
never found far apart, but haunt the same stream 
or marsh all the year round. Azara says that in 
Paraguay, where they are rare, they go in pairs and 
breed in trees. On the pampas it makes its solitary 
nest amongst the rushes, and lays three blue eggs. 
The following general remarks on the Heron 
apply chiefly to the Ardea cocoi, and to some extent 
also to other species of the Heron family. 
I have observed Herons of several species a good 
