Clark et al. • SCINTILLANT AND VOLCANO HUMMINGBIRD COURTSHIP 
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FIG. 5. Shuttle anti dive display kinematics of the Scintillant Hummingbird. (A): sketch of the traveling shuttle display, 
traced from frames of a high-speed video, Tracings are of the bird's posture teach wing, head, body, and tail) every 8 ms. 
The male was flying towards die camera with little lateral motion, Initially, the bird was flying towards the camera while 
the wings flapped symmetrically and the body's roll angle was nominally zero (0 ms). At 8-24 ms, the wing motions 
abruptly became asymmetric (i.e„ the wings differed in stroke amplitude, stroke angles, and moved out-of-phase by up to 
90 ), and the tail was abruptly spread and twisted up and to the bird's left, while the body’s roll angle rotated to —90 (left 
side down; bird’s ventral side towards camera). The spread tail proceeded to sweep around rapidly (24-48 ms) from left to 
right, and towards the end of this motion the bird's roll angle returned to 0 . The wings returned to flapping symmetrically 
(56-64 ms) at the end of the shuttle. The w ings did not appear to strike any part of the bird’ s body during these motions, and 
six wing beats occur within the 64 ms depicted. (B): sketch of the dive trajectory with stages 1-3 labeled. Males undulated 
slightly as they ascended. Stage I: flapping with tail shut, 2; gliding with tail shut. 3. flapping and spreading tail. Stage 2 is 
only present in some dives. Subsequent dives were in the opposite direction from previous dive. 
Display Dives— Male Scintillant Humming¬ 
birds would approach u caged female, but this 
did not elicit dives (n - 3 males), similar to 
territorial male Allen's and Rufous (CJC, pers. 
obs.). We recorded natural dives from one male, 
and elicited dives from two males by releasing a 
Scintillant female on territory. The male would 
perform a shuttle display, followed by 1-6 dives, 
to females that landed in his territory. We 
recorded sounds of 17 dives from three males. 
The primary audible sound during the dive was 
the sound of the wing trill. Two additional faint 
sounds were present in seven good sound 
recordings (Fig. 4C). The dive began with the 
wing trill produced at a rate or92.5 ± 1.9 Hz (// = 
17). There was a gap lasting 0.32 ±. 0.12 sec in 
production of the trill early in the dive in seven of 
17 dives. Two to six faint pulses (p in Fig. 4C) of 
sound were produced (/? = 7 dives) al the bottom 
of the dive at a temporal rate of 16 ± 2.7 Hz (n = 
7). An additional trill appeared (trill 2 in Fig. 4C) 
at the same time these pulses were produced with 
an average pitch ranging from 5.3 to 5.4 kHz and 
a bandwidth of 0.76 kHz (n = 16). Trill two had a 
harmonic that was slightly higher in pitch than the 
wing trill. 
Males began a dive by ascending on a slightly 
undulating path to a height of —25 m (Fig. 5B). 
The male would then turn and dive at a steep 
angle, swooping directly over the female and then 
rise again, tracing a giant U. At the end of the first 
dive the male would then turn and perform the 
next dive, following the same path but in the 
opposite direction from the previous dive, in the 
same vertical plane. 
We obtained high-speed videos of part of four 
dives from two males. All lost the bird partway 
through the bottom of the dive. Males began the 
dive by powering their descent with flapping 
wings (stage 1). Males continuously flapped for 
the entire dive in three dives while in the fourth 
the male briefly switched to a glide (stage 2). 
Males repeatedly spread and shut their tail at the 
bottom of the dive while continuing or resuming 
