Figure 1.

Satellite tracks of migrating bar-headed geese: (a) three-dimensional map showing release locations (black crosses) of bar-headed geese in India (n = 2 sites) and Mongolia (n = 1 site). Coloured lines represent 16 individual geese, and coloured background shading indicates elevation. Solid thick white line shows the great circle route. White crosses show locations of the 14 ‘eight-thousanders’ (the world's highest mountains, each over 8000 m in elevation). Five peaks are largely obscured owing to their proximity to other peaks. (b) Cross-section of land elevation under the arithmetic mean bar-headed goose northwards migration from Indian wintering (left side of plot) to Chinese and Mongolian breeding grounds (right side of plot).