Speed fixes greater than 10 km/h were a reliable indication that a vulture was in flight
(although soaring vultures were occasionally recorded at 0 km/h, presumably indicating a bird
flying into a headwind or manoeuvring in a tight circle). Roost positions did not exceed 256 m
elevation above sea level for any vulture during the study period, and this was assumed to be the
maximum altitude at which a vulture could be perched in the study area. Vultures were
considered to be flying for all fixes obtained at altitudes exceeding 256 m, or when speed was
greater than 10 km/h at altitudes less than 256 m.