Fig. 14

Orographic updrafts resulting from wind at the direction indicated (top row), and the resulting presence map (bottom row) for fall migration in the Appalachian region. The updraft color scale is such that it is blue when updrafts are above the 0.85 m/s threshold and can be used for orographic soaring. The bottom row includes the elevation map in light gray combined with relative presence density in green (darker green indicates higher density). The starting position of the simulated birds is near the north boundary, and their movement intention is shown by the arrow. a Typical low wind speed conditions at 80 m AGL; b typical high wind speed conditions at 80 m AGL