Homing behavior of pigeons after telencephalic ablations.

In a first experiment, dorsomedial forebrain ablated birds showed similar homeward orientation when compared to untreated controls independent of whether the birds were released from a previous training site or a site they had never been before. However, although all control birds returned to the home loft, only 2 of 28 birds with lesions homed successfully. In a subsequent experiment, both sham operated control birds and birds with lesions of the visual Wulst homed successfully when released only 800 m from and in full view of their respective home lofts. Pigeons with dorsomedial forebrain lesions, however, failed to return to their respective home lofts. The results show that the avian dorsomedial forebrain plays a critical role in that step of the homing process by which a pigeon returns to its home loft once in its vicinity, and that the failure to reassociate with the home loft is a likely result of deficient recognition of the home loft and/or its surrounding area. In an additional experiment, pigeons with Wulst lesions were shown to orient as controls and to successfully return to the home loft when released from two distant sites. This experiment demonstrated that the avian Wulst plays no necessary role in the homing behavior of pigeons.