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48 Ramphocelus, Dec. 23, 1958, II. the time the other appears in sight! There is no doubt now but that the Black-throats tend to feed higher than the Silver-bills. Although there is a very very wide zone of overlap, I have never seen the Silver-bills go so high in big trees as the Black-throats sometimes do, and the only time I have seen the Black throats feeding as low as a foot or two from the ground like the Silver-bills do so frequently was when both families had joined together to form a particularly close-knit little flock. In other words, the Silver-bills seemed to have dragged the Black-throats down with them! The association of the 2 species may thus provide a greater range of food for both but it must increase the competition between them. I think that either species is about equally likely to lead the other. When they were following the same routes in the same direction, once the Silver-bills followed the Black-throats and once the Black-throats followed the Silver-bills! The Black-throats may tend to give ordinary CN's a little more frequently than the Silver-bills, and then CN's tend to be somewhat metallic-sounding. They also have a "Wheeeet" CN pattern more or less like that of the Silver-bill. Several times this morning I have heard an adult utter a series of "Whiit" or "Wheeeet" Notes,including anything from 3 notes to 7 or 8, when it flies away ahead of the rest of its family. Although both species are somewhat specialized to further (?) with their considerable restlessness, rather frequent CN's, and exaggerated TF's, this mixed flock does not (not is underlined) seem to be at all attractive
