Fig. 1. Circular diagram of the vanishing bearings of the control (filled circles) and clock-shift (open circles) groups released 9.95 km from home in Oxford, UK. Birds were released individually and followed through binoculars until they vanished from sight. Bearings at vanishing were recorded for each bird. The mean bearings and vectors are shown in the diagram as the arrows in the inner circle (filled arrow, control; open arrow, clock shift). r is the mean vector length, and is the mean vanishing bearing. The edge of the inner circle represents a vector length of 1. The single-headed arrow represents the home direction (H), and the double-headed arrow represents the predicted home direction for clock-shifted birds (CS). Reproduced from Holland (1998).

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