Figure 1.
Energy demands of flapping flight increase with body mass (E = M1.17; [13]) more rapidly than do basal metabolic rate (BMR = M0.78; [16]) or energy demands of soaring/gliding (2× BMR; [14], [15]). Schematic shows these relationships, assuming constant body and wing shape, size and wing loading.
Figure 2.
Altitude and topography of flight types.
Flight modes were manually classified based upon flight patterns, changes in flight altitude, and underlying topography for locations of golden eagles during spring migration 2009–2010. A) Thermal soaring includes points (triangles) that are closely spaced with increasing altitude. B) Gliding points (circles) connect flight segments of thermal soaring, with points decreasing in altitude. C) Slope soaring segments include locations (squares) along ridgelines that are close to ground level (less than 200 m). The background map shows topographic relief with darkened slopes of ridgelines.
Figure 3.
Progress path and progress distance.
The progress path is the straight line that connects the first and last points that a satellite tag recorded for each golden eagle as it migrated from the 39.5° to the 42.5° north latitude. For each flight segment, the progress distance is the distance along the progress path defined by the latitudes of the start and end points of the segment. The progress speed is the quotient of the progress distance for the segment and the time an eagle spent traveling along the actual path of the segment.
Table 1.
Mean ± s.e. ground and progress speeds for flight modes used by five golden eagles migrating through Pennsylvania during spring migration, 2009–2010.
Table 2.
Model parameters ± s.e. and statistics for effects that influence ground and progress speed (m s−1) of golden eagles as they passed through the central Appalachians during spring migration, 2009–2010.
Table 3.
Means ± se of predictor variables and time measures for flight modes used by five golden eagles that migrated through Pennsylvania during spring, 2009–2010.