NOETH AMERICAN MARSH BIRDS 201 



the ground. On Juno 8, 1919, 1 found a colony of from 200 to 300 pairs 

 probably the same olony, nesting in an extensive patch of low cedars 

 near the shore, a mile or more away ; even at that date most of the 

 nests contained young, some of which were fully grown and were 

 •climbing out on the branches. Dr. Charles W. Townsend showed 

 me, on July 19, 1913, a somewhat different type of rookery in Ham- 

 ilton, Massachusetts, which he had previously described ; it was in a 

 mixed swamp of larches, black spruces, white pines, and maples in 

 which the nests were from 20 to 30 feet up; the young were nearly 

 all on the wing, but there were still a few in the nests. 



I have seen several night heron rookeries on the coast of Maine, 

 where this species nests in colonies by itself or in company with the 

 great blue heron. Referring to some of these colonies Doctor Gross 

 (1923) says: 



lu Maine, spruce-covered islands or dense groves of conifers on the mainland 

 near the salt water are the places where one is most likely to meet with success 

 in locating the largest breeding places and roosts. Mr. A. H. Norton of the 

 Portland Natural History Society visited Aliens Island in June, 1921, and found 

 a rookery comprising about 100 great blue herons, and nearly 400 black-crowned 

 night herons. The nests on Aliens Island were built at an average height of 25 

 feet in the low spruce trees which there do not exceed 30 to 40 feet in height. The 

 majority of the nests were supported by the lower branches of the green conical 

 tops so that they were in plain view to an observer standing on the forest floor. 

 Several ravens were seen at this colony and Mr. Norton thinks some of the dead 

 half-eaten j'oung that were lying on the ground represented the work of these 

 black marauders. The colony at Whaleboat Island which contained only 30 

 pairs of herons in 1915 has increased to a thriving community of more than 250 

 birds, not including about 50 great blue herons which regularly nest there. The 

 nests seen here were without exception built in the tall dead spruces, those of the 

 night heron at an average height of 34 feet from the ground. None of them 

 were lower than 10 feet and one was l)uilt near the top of a tall spruce more 

 than 60 feet in height. At this place there seemed to be a rough correlation 

 between the height of the trees and the position of the nest. The majority of 

 the nests were nearly the same distance from the top of the respective trees, a 

 place where the densely branched limbs were best adapted for holding the nest. 

 They were built near the trunk and were usually supported by the bases and 

 smaller lateral branches of two or more horizontal limbs. 



In other parts of the country night herons nest under widely 

 different conditions. Where suitable trees can not be found in 

 favorable localities the herons are often found breeding in marshes 

 -or sloughs, where their nests are concealed in some secluded spot. 

 Robert B. Rockwell (1910) found a particuhxrly interesting colony 

 •of this type near Barr, Colorado, of which lie writes: 



As we approached the spot where the colony was supposed to be located, not 

 a sign of the birds was to be seen — save the monotonous expanse of cat-tail 

 marsh, flanked by a small rush-bound lake on one side and the sunburned prai- 

 rie on the other. We had worked well into the cat-tails, which towered some 

 distance above our heads, when as if by a given signal the breeding birds rose 



