THE O. & O. SEMI-ANNUAL. iy | 
TE GREAT BLUE SIER@N: 
Ardea Herodias. 
BY F.W.CURTIS, WAUWATOSA, WIS. 
The Great Blue Heron breeds in suitable localities throughout this 
state. A heronry of this species that I have in mind is about twelve 
miles from this place. This heronry is in the heart of an almost im- 
passable tamarack swamp, and covers over about ten acres of swamp. 
There are, I should judge, about one hundred and fifty nests, some- 
times two and three in a tree, ranging from 45 to 75 feet from the 
ground. Where the nests are at the extreme heighth given, the trees 
are often only three inches in diameter, and it is a trial of one’s nerves 
to be up in the air on so small a support. 
The nests are very bulky, 3 to 5 feet across, composed of sticks. 
The hollow in which the eggs are deposited is lined in some instances 
with straw, but the majority have no lining whatever. The branches 
of the trees afford little or no support on account of their small size, 
and so the nests are built entirely around the tree, thus adding greater 
security to the whole structure. On one side is a larger shelf, as it 
were, on which the eggs are deposited ; this is the nest proper. 
The number of eggs in a clutch varies from three to five, four be- 
ing the usualnumber found. Incubation extends from about the 2oth 
of April to the 15th of May and even later. 
Three sets of four eggs each, total 12 eggs, in my collection, average 
respectively : Set I, 2.68x1.82 ; Set II, 2.56x1.81 ; Set III, 2.54x1.82. 
To:al average, three sets, 2.59x.1.81. Ridgeway, in his manual of N. 
A. Birds, gives 2.50x1.50, subject to variations, as the measurements. 
It will be noticed, especially in the first set, that this is true. Like 
all the eggs of the Herons, the eggs of this species are unspotted, of 
both light and dark shades of bluish-green, more or less soiled by 
contact with the nests and marked somewhat with calcareous material. 
In the Great Blue Heron, the crown of the head is pure white, 
with two or three black feathers dependent from tie back of the head ; 
neck grayish-brown, back aud wings slate-blue, changing upon lower 
parts of wings and tail to black ; under parts, black and white ; legs 
and feet black. 
