198 THE YELLOW-HEADED BLACKBIRD. 
while crossing the Plains. They would collect about camp in 
the evening, with flocks of Cowpen birds, and ramble about for 
food among the mules and horses turned out to graze. In spite of 
the season of the year, I noticed that a large part of them were in 
imperfect plumage, the inference from which is, that more than 
one year is required for them to become perfectly black and yellow. 
I saw them at various points along the Rio Grande, and first 
found them breeding a short distance west of that river, near the 
Pueblo of Laguna. A small stream there spreads into a marsh, — 
overgrown with reeds and tall rank weeds ; a favorable spot, that 
thousands of the birds had selected as a nesting place, and were 
then busy with the duties of incubation. Pretty much all these 
birds seemed to be in perfect plumage, and no young of the year 
had yet made their appearance. pois 
The nest of this species is a compact, substantial structure, 
measuring five or six inches across, and but little less in depth. 
Unlike the true Agelwi, or Marsh Blackbirds proper, these birds 
use no mud in the construction of the nest— perhaps because its 
weight would then be too much for the slender reeds to bear; the 
nest being placed in a tuft of upright flags or rushes, the stems of — 
which pass through the substance of its walls, and securely fasten 
it, though it is liable to sway back and forth in the wind. Itis 
plaited and woven entirely of bits of dried reeds, and long, coarse, 
aquatic grasses, and is not lined with different material, though the 
inside strands are finer than those outside. The brim of the nest — 
is usually thickened, and folded over a little, to form a firm edge. 
The eggs may be from three to six in number. They resemble the 
` eggs of the Scolecophagi more than those of the Agelei, lacking 
the curious straggling zigzag lines. The ground color is 4 pale 
grayish or olivaceous green, which is spotted all over with se 
shades of reddish-brown, sometimes so thickly, especially towards 
the larger end, that the ground color is scarcely perceptible. The 
eggs vary to a moderate degree in size and shape; two sel 
specimens measured respectively 1.04 X .75 and 1.15 X .76. 
_ The duties of incubation devolve mostly upon the female, and 
while she is setting, the male is fond of mounting the highest pereh 
near the nest, and giving free expression to his joyful anticip® 
tions. He twists and turns about in a curious way, and sings, es 
a manner still more amusing, a queer melody of guttural notes, 
broken at intervals by an odd grating sound, and again by afew 
