ABSTRACT
When homing pigeons are released, they usually do not depart directly towards home, but deviate from the home direction: the so-called ′release site bias′ (Keeton, 1973 as a translation of the German Ortseffekt by Wallraff, 1959a). These deviations, which were first described by Kramer (1957), vary in size. At most sites, they are not very large, but occasionally may be as much as 180°. Releases at the same site normally produce very similar results, which are independent of weather conditions, age and general experience of the birds (Wallraff, 1959b) so that the bias is characteristic for any given location (Keeton, 1973). In view of the modern concepts of a learned navigational ′map′ (see Wallraff, 1974; Wiltschko & Wiltschko, 1978, 1982, 1987) it is interesting to know how local experience at the site itself could affect the pigeons′ behaviour.
