414 Mr. E. Gibson on the Ornithology of 



Breeding -Notes. — In the year 1873 I was so fortunate as to 

 find a breeding colony in one of our largest and deepest 

 swamps. There were probably twenty or thirty nests, placed 

 a few yards apart, in the deepest and most lonely part of the 

 whole " canadon " (superlative of " Canada ") . They were 

 rarely built up from the water, like the Chimangos {M. chi- 

 mango), but, being very slight structures, were easily sup- 

 ported by the " bunco " (a water-rush) at a height of from 

 two to three feet above the water, and consisted of slight 

 small platforms of dead " durasnillos " (a woody-stemmed 

 water-plant) , with a cup-shaped hollow in the centre, the latter 

 lined with pieces of green bunco, particularly the flower and 

 seed- tufted extremities. Among the nests of R. sociabilis I saw 

 two or three of the Chiraango {Milvago chimango) and a few of 

 our common Night-Heron (Nycticorax obscurus, Bp. ?), of 

 which there was also a breeding colony about a hundred yards 

 off*. During my presence the birds remained high overhead, 

 shifting their position slightly every now and then, and uttering 

 their creaking cry at intervals. On the 23rd November I 

 took twenty-six eggs (no clutch exceeding three in number) , 

 while only two nests had young (two apiece). On the 30th 

 most of the eggs were much incubated ; and on the 21st De- 

 cember some of the young birds had flown, others were of 

 various sizes, and only a very few nests still had eggs. There 

 were no old nests to be seen about the colony, showing that 

 the site had only been selected that year; and neither there 

 nor anywhere else in our locality have I found R. sociabilis 

 breeding since. 



The eggs, as I have said, never exceed three to the nest ; 

 and the average of twenty-two specimens gives If ^ x 1^^ as 

 their measurement, the largest of the series being If-^ X 1^, 

 and the smallest If^ x \\^. They much resemble those of 

 the Sparrowhawk, and also vary greatly. The ground-colour 

 is generally a bluish white, blotched and clouded very irregu- 

 larly with dull red-brown ; but the rufous tinge is sometimes 

 absent, or is replaced by ash-grey. In short, it would take 

 a large series of eggs in order to produce what might be called 

 a typical set of eggs. 



