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Observations on the Horned Screamer
Frank B. Gill, F. J. Stokes and C. C. Stokes
The Wilson Bulletin
Vol. 86, No. 1 (Mar., 1974), pp. 43-50
Published by: Wilson Ornithological Society
Stable URL: http://www.jstor.org/stable/4160433
Page Count: 8
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A population of 35 Horned Screamers was observed for eight days in the llanos of Colombia. The birds tended to be sedentary, remaining on a single perch for as much as two hours during the morning. Occasional flights to new perches were rarely longer than 200 m. The birds were never seen soaring and only rarely seen flying. Three basic vocalizations were used--loud goose-like Honking and Trumpeting and a somewhat melodious Moo Co. Calls were limited almost completely to the morning hours before the birds fed. Isolated pairs frequently duet with the Moo Co, primarily in response to disturbance. Arrivals of relocating individuals were typically accompanied by Honking, often with head bobbing. Communication between groups scattered around the lake involved Honking, Trumpeting and Moo Cos. The low fundamental frequencies and the well-developed harmonic of these calls suggest a long trachea (about 30 cm). Comparison is made with the other two members of the family--Chauna chavaria and C. torquata, and the behavior of certain waterfowl, especially the Magpie Goose, Anseranas.
The Wilson Bulletin © 1974 Wilson Ornithological Society