Cape San Antonio, Buenos Ayres. 35 
sufficient to notify its approach. This whistle is its only note 
or call, and also serves to express warning and alarm. 
Breeding-Notes.—It nests very early ; for I have taken a 
nest on the 24th of July, the five eggs of which were much 
incubated. July and September are the favourite mouths ; 
but eggs may be taken as late as the middle of November. 
The position chosen is always in one of the largest and deepest 
swamps, the nest being placed among the thickest rushes, at 
some distance from one of the lagoons, but connected with 
it by a lane of clear water; for the birds always leave the nest 
by swimming. It is built from the bottom of the swamp, 
sometimes through four or five feet of water, above the sur- 
face of which it rises a foot or a foot and a half. The dia- 
meter at the top is about two feet, the depression for the eggs 
slight, with a few feathers from the Swan scattered about it, 
but not sufficient to be called a lining. Dry rushes, of the 
common kind known as “ hunco,”’ form the building-material. 
It is a pretty strong, compact structure, but not sufficiently 
so to support a light man’s weight, as I found to my cost on 
springing from my horse onto the first nest I found ; for it 
immediately subsided, and left me waist-deep in the water, 
with a young horse to mount proverbially known for its 
quickness, and barebacked into the bargain. Never mind 
how I managed to regain my seat ultimately ; but I carried 
off the eggs in triumph. 
Nothing would be easier than to expatiate on a certain day 
in the Cisneros swamp, such as I had two years ago, with a 
tame old horse under me, firm ground underneath, the water 
unusually clear and free from weeds, and so deep that only 
the seat of the saddle was above its surface. I spent three 
hours in the heart of this swamp, on a calm sunny day, floating 
noislessly along the narrow open channels among the bright 
green rushes—now seeing a Swan swim slowly away from its 
great nest, where lay the three or five large handsome eggs— 
again stopping to poke up the suspended nest of that curious 
aquatic opossum (Didelphys crassicaudata, Desmarest), and 
watch the truculent little villain spring out and also swim 
or dive away puffing viciously—then turning my horse to 
v2 
