FIGURE 3. (A) Wing-lifting display of male Eastern Blue bird (Sialia sialis). From Fig. 28 of Grieg (1971). (B) Variants of wing raising in the ground tyrant Muscisaxico/a albilora. From Fig. 3 of Smith (1971 ). [CJ Frequency distributions of height of wingtip in wing-lifting display of the Eastern Blue bird,illustrating hypothetical situation sranging from clear unimodality (I) to clear bimodality (IV) (see text for discussion).