172 BULLETIN 135_, UNITED STATES NATIONAL MUSEUM 



by these birds. On stepping ashore I was startled at seeing hundreds of Louisi- 

 ana herons spring up from the open, treeless marsh and immediately settle down 

 again as I sank to cover. A few steps into the thick matted rushes and again 

 the birds arose on liurried wing beats almost directly upwards and drifted with 

 much croaking farther down the island. A few steps more and I was in the midst 

 of a nesting colony of these birds; every few yards a nest directly on the depressed 

 rushes where a high tide had beaten down the tops of the tall rank growth. 

 A hurried estimate of the number of these birds made approximately 500 individ- 

 uals, but whether both sexes were in the marsh I could not determine, and no ac- 

 curate count of the nests was attempted, as'they extended to a considerable distance 

 in at least two directions — just how far was not discovered — and an enumeration 

 under the condition would have required more time than could be spared then, 

 but enough was seen to convince me there were more than 150 nests, while there 

 might have been two or three times that number. The nests contained from 

 one to five eggs, but for the most part four, as far as examined all were freshly laid. 

 The nests were but little more than the scratching aside of the tangled rushes 

 and a few broken pieces of the same laid crossing one another to aid in retain- 

 ing the eggs from working down. 



Eggs. — The Louisiana heron usually lays four or five eggs, some- 

 times only three, occasionally six or very rarely seven. In shape they 

 vary from ovate or oval to elliptical ovate or elliptical oval. The shell 

 is smooth, not glossy. The color is pale bluish green, varying from 

 "pale Niagara green" to "lichen green." 



The measurements of 41 eggs average 44.1 by 32.3 millimeters; the 

 eggs showing the four extremes measure 60 by 33, 48 by 34, 40.8 by 

 32, 44 by 30.5 milUmeters. 



Young. — Audubon (1840) gives the incubation period as 21 days. 

 Both sexes incubate the eggs and guard the young; from the time 

 that the nesting site is chosen until the young leave the nest one of 

 the parents is always on duty. As one walks through a rookery it 

 is easy to locate the nests containing young by their plaintive peep- 

 ing notes. The young remain in the nests until they are half or two- 

 thirds grown, probably longer if not disturbed; at this age or older 

 they are easily frightened and readily leave the nest, climbing with 

 great agility over the surrounding branches. They are quite expert 

 at climbing, though apparently awkward, and can cling quite tena- 

 ciously with bill, wings, or feet. They sometimes fall, however; if 

 they fall into the water they can swim quite well and may be able to 

 reach their nests again; but occasionally they become entangled in 

 the branches, or in the sticks of the nests, which usually proves fatal, 

 as their parents do not seem able to help them in such situations; we 

 saw a number of their dead bodies hanging where they were caught. 

 The young are fed by regurgitation, after the manner of other herons, 

 as long as they remain in or about the nests, and probably longer, 

 until they learn to shift for themselves. 



Plumages. — The downy young Louisiana heron is distinctively 

 colored, quite unlike any of the others. The top of the head is 

 covered with long hairlike plumes, nearly 041 inch long, shading from 



