Figure 3.

(a,b) Orientation versus downwind direction for insect targets observed at a radar site at Mara River (1°03′ S, 35°15′ E) in southwestern Kenya, in March 1982. Orientation was approximately towards the north in a variety of downwind directions (west through northeast). (c) Example of a crosswind unimodal heading at Mara River 9 March 1982, 20.41–21.02 h, at an altitude range of 540–600 m. The distribution shown is of body alignment—an axial quantity, but the shaded section indicates the ‘head end’ direction, deduced from other information. The mean heading was towards 338° (circular s.d. 24.8°), i.e. aligned at 63° to the mean displacement (D) which was towards 270–280° at 11 ± 2 ms⁻¹. Wind speed of 10 ms⁻¹ was directed towards 264°.