the other notes of the female being long powerful notes with a trill in them; but over them sounds the clear piercing voice of the male, ringing forth at the close with great strength and purity. The song produces the effect of harmony, but, comparing it with human singing, it is less like a duo than a terzetto composed of bass, contralto, and soprano.
At certain times, in districts favourable to them, the chakars often assemble in immense flocks, thousands of individuals being sometimes seen congregated together, and in these gatherings the birds frequently all sing in concert. They invariably--though without rising--sing at intervals during the night, "counting the hours," as the gauchos say; the first song being at about nine o'clock, the second at midnight, and the third just before dawn, but the hours vary in different districts.
I was once travelling with a party of gauchos when, about midnight, it being intensely dark, a couple of chakars broke out singing right ahead of us, thus letting us know that we were approaching a watercourse, where we intended refreshing our horses. We found it nearly dry, and when we rode down to the rill of water meandering over the broad dry bed of the river, a flock of about a thousand chakars set up a perfect roar of alarm notes, all screaming together, with intervals of silence after; then they rose up with a mighty rush of wings. They settled down again a few hundred yards off, and all together burst forth in one of their grand midnight songs, making the plains echo for miles around.
There is something strangely impressive in these
The Crested Screamer. 227
spontaneous outbursts of a melody so powerful from one of these large flocks, and though accustomed to hear these birds from childhood, I have often been astonished at some new effect produced by a large multitude singing under certain conditions. Travelling alone one summer day, I carne at noon to a lake on the pampas called Kakel--a sheet of water narrow enough for one to see across. Chakars in countless numbers were gathered along its shores, but they were all ranged in well-defined flocks, averaging about five hundred birds in each flock. These flocks seemed to extend all round the lake, and had probably been driven by the drought from all the plains around to this spot. Presently one flock near me began singing, and continued their powerful chant for three or four minutes; when they ceased the next flock took up the strains, and after it the next, and so on until the notes of the flocks on the opposite shore came floating strong and clear across the water--then passed away, growing fainter and fainter, until once more the sound approached me travelling round to my side again. The effect was very curious, and I was astonished at the orderly way with which each flock waited its turn to sing, instead of a general outburst taking place after the first flock had given the signal. On another occasion I was still more impressed, for here the largest number of birds I have ever found congregated at one place all sung together. This was on the southern pampas, at a place called Gualicho, where I had ridden for an hour before sunset over a marshy plain where there was still much standing
Q 2
228 The Naturalist in La Plata.