. Bulletin of the British Ornithologists' Club. . Fig. 2. Display phases of Orthorhyncus cristatus exilis (see text). 1) The male hovers with erected green iridescent crest in a vertical position in front of the female about half a metre distant. 2) The male flies in 'slow-motion' at a high wing-beat rate towards the female and abruptly claps the wings against the fanned retrices, producing a mechanical noise. 3) Immediately in front of the perching female the male, still with erected crest, starts flying to and fro at high speed in a semi-circle around the female. At the end of each semi-circ
. Bulletin of the British Ornithologists' Club. . Fig. 2. Display phases of Orthorhyncus cristatus exilis (see text). 1) The male hovers with erected green iridescent crest in a vertical position in front of the female about half a metre distant. 2) The male flies in 'slow-motion' at a high wing-beat rate towards the female and abruptly claps the wings against the fanned retrices, producing a mechanical noise. 3) Immediately in front of the perching female the male, still with erected crest, starts flying to and fro at high speed in a semi-circle around the female. At the end of each semi-circle the male again produces a mechanical sound by beating the wings against its widely spread tail- feathers. During this flight pattern of the male, the colour of the iri- descent green crest changes in relation to its angle to the female. The iridescence is optimally displayed when the male is exactly centrally in front of the female. The male repeats this flight 4-6 times. During the male's display the female is motionless except for slightly opening the beak in phase 3. Thereupon, the male copulates with the female. A similar display has been observed with the Wire-crested Thorntail Popelairia popelairii (Schuchmann 1976). Acknowledgement: The hummingbird research project was kindly supported by G. Charles, Dept. of Forests, Castries, St. Lucia, J. W. Glover gave the manuscript a critical reading. References: Bond, J. 1961. Birds of the West Indies. Collins: London. Colwell, R. K. 1973. Competition and co-existence in a simple tropical community. Amer. Nat. 107: 737-760. Feinsinger, P. 1975. On the relationship between wing disc loading and foraging strategy in hummingbirds. Amer. Nat. 109: 217-224. Pitelka, F. A. 1951. Ecologic overlap and interspecific strife in breeding populations of Anna and Allen Hummingbirds. Ecology 32: 641-661. Schuchmann, 1976. Beitrag zur Biologie des Haubenfadenkolibris, Popelairia popelairii. Z. Koln. Zoo 19: 11-13. Address: Karl-L. S
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