Ocean Surface Winds Drive Dynamics of Transoceanic Aerial Movements
Figure 4
Coupling of Cory's shearwaters migration to the stopping of westerly winds developed during the peak months of the African Monsoon in the Atlantic sector of the Intertropical Convergence Zone (ITCZ).
QuikSCAT winds on 7 September 2002 (4A) and 15 November 2002 (4B) showing the migratory “gate” located at 10°–15° N blocked and opened, respectively. Wind speed in the background increases from fuchsia (0 m·s−1) to green (6 m·s−1) to red (15 m·s−1), and arrows show wind direction. 4C, Migration (hatched red bars) starts when the frequency of blocking winds drops (black bars; winds blow towards 75°–115°). In the returning trip (range: February 11–March 10), there are no westerlies blocking the passage to the breeding areas in the Northern Hemisphere (not shown).