Maclean 1964 10 June 3 displaying O's between NACS and Drum area. Little interaction. After 15 min. one singing over entire area; others gone (?). 2 displaying over garlic ridge. Cueing - 1 display heard over both bluffs. Otherwise nothing! 11 June 1 on ground E. of High Explosives dump (drum area) - silent feeding 1 min. - flew 40 ft, gave trill. Flew 100 yps - aerial display for ca. 15-20 sec. Fly up to 20 ft - glide, then give "twittering" trill with wings nearly level, vibrating at about same frequency as trill note (connection between muscles causing wing vibrations and sound?) Hear some (?) displaying ca. 150 yps NE. 5 min. - back, feeding. Flew 100 yps N - short aerial display (<5 sec.) 1 min - 2 SP back. 1 approaches other - tail up 45° . Raised 1 wing 60°, then other . Other bird flew 60 ft; displaying bird followed; landed 1 ft. away, separates as foe. Aggressor flew off rapidly, displayed 10 ft. above ground, drove off intruder. Neutral bird follows. Both landed 150 yps. SE. Near w/ 4 eggs (SP-1) located - center of polygon in low grass. Fairly deep (ca. 1½") cup lined with grass, few lichens. Deeper, better protected, better lines than Bairos. ♀ gave twittering trill c.a. 40 ft. away - no distraction display. Flew when approaches. ♂ came, joined in trill. ♂ harsher,