Article Figures & Tables
Figures
- Table 1.
Mean morphological and kinematic values for Selasphorus hummingbirds in the Colorado Rocky Mountains
Gender Elevation m (g) R (mm) n (Hz) Φ (degrees) WDL (g m-2) S. platycercus Females 1875 3.375 56.398 34.078 146.431 0.042 2900 3.592 57.790 37.669 151.742 0.041 Males 1875 3.332 54.816 37.181 149.348 0.043 2900 3.360 54.355 37.890 151.999 0.043 S. rufus Females 1875 3.331 45.238 44.747 144.998 0.065 2900 3.800 47.711 47.623 161.085 0.060 Males 1875 3.404 42.754 54.066 163.893 0.066 2900 3.601 42.496 55.563 167.573 0.071 -
Stroke amplitude (Φ) and wingbeat frequency (n) were measured during free flight at each site
Body mass (m), wing length (R), and Φ were used to calculate the wing disc loading, WDL
Free-flight wingbeat kinematics were attained for S. platycercus females although these birds were not included in flight trials
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- Fig. 1.
Hovering kinematics in hypodense air. As ambient air was replaced with normoxic heliox, air density decreased but the partial pressure of oxygen remained constant. The data depicted here were from the experiments performed at 1875 m, although the same trends were evident at 2900 m. (A) Wingbeat frequency increased slightly with decreasing air density. (B) Stroke amplitude increased substantially with decreasing density to a limit near 180°. Values are means ± s.e.m.
- Fig. 2.
Hovering kinematics in hypoxic air. As ambient air was replaced with pure nitrogen, the partial pressure of oxygen declined but the air density varied only slightly. Otherwise, conditions were identical to that of the first experiment described in Fig. 1. (A) The wingbeat frequency decreased slightly but significantly as oxygen partial pressure decreased (see text). (B) Stroke amplitude varied considerably but exhibited no clear pattern with changing partial pressure of oxygen. Values are means ± s.e.m. All symbols as in Fig. 1. 1 mmHg=133.3 Pa.
- Fig. 3.
Kinematics in hyperoxic air. As ambient air was replaced with hyperoxic heliox, air density decreased and oxygen concentration increased simultaneously. During normoxia trials, ambient air was replaced with normoxic heliox so that air density decreased but oxygen concentration remained at 21%. Hummingbird kinematics in hyperoxia were equivalent to those in normoxia. Values are means ± s.e.m. See text for details. %O2 is the oxygen concentration at each density under hyperoxia.
- Fig. 4.
Wingbeat kinematics during hovering across a natural elevational gradient in the Peruvian Andes. Data are species mean for 43 species of hummingbirds. (A) Wingbeat frequency decreased with increasing body mass. The largest hummingbird is the giant hummingbird Patagona gigas, which is substantially larger than all other trochilid taxa and is considered an outlier. However, the decrease in wingbeat frequency with body mass is found even if P. gigas is removed from the analysis (inset; all P<0.001; see text). (B) Stroke amplitude increased with increasing elevation, mirroring the results of experiment 1 ( Fig. 1). See text for regression equations.
- Fig. 5.
Wingbeat kinematics during free hovering and load-lifting in Peruvian hummingbirds. (A,B) Raw species data, (C,D) phylogenetically corrected independent contrast data. Solid lines, free flight; broken lines, load-lifting. Wingbeat frequency decreased with increasing body mass during both load-lifting and free hovering flight. Stroke amplitude increased with increasing elevation during free flight, but not with elevation during load-lifting, because all hummingbirds reached a maximum stroke amplitude of approximately 180° at the point of maximum lifting. See text for regression equations.
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