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Recent findings indicate a different role of the left and right hippocampal formation (RHF) in homing pigeon navigational map learning. However, it remains uncertain whether the left or the RHF may play a more important role in navigation based on familiar landmarks. In the present study, we attempted to answer this question by experimentally releasing control and left and right hippocampal ablated pigeons from familiar training sites under anosmia, to render their navigational map dysfunctional, and after a phase-shift of the light-dark cycle, to place into conflict a pilotage-like landmark navigational strategy and a site-specific compass orientation landmark navigational strategy. Both left and right hippocampal ablated birds succeeded in learning to navigate by familiar landmarks, and both preferentially relied on sun-compass based, site-specific compass orientation to home. Like bilateral hippocampal lesioned birds, and in contrast to intact controls, neither ablation group adopted a pilotage-like strategy. We conclude that both the left and RHF are necessary if pilotage-like, familiar landmark navigation is to be learned or preferentially used for navigation.

Orientation and homing performance of pigeons with the left or right eye occluded were assessed in an arena at the release site and during the subsequent homing flight. Three release sites near Pisa, Italy, were used. Compared to binocular controls, monocular birds showed a bias in orientation towards the side of the viewing eye. In the arena, this bias was considerable and the mean deviation corresponded to the angle of the optical axis, suggesting a systematic error in visual representation during directional orientation. During flight after leaving the arena the directional bias decreased and the homeward orientation increased. While there was a slight lateralization of overall homing performance in favour of the right eye, there was no lateralization in directional orientation in the arena or at vanishing. Our results show that navigational mechanisms in either brain hemisphere profit from information obtained before take off and while flying over the release site. The existence and degree of lateralization is discussed in comparison to other studies that investigated homing under monocular viewing conditions.

Experiments were performed with homing pigeons treated before release with oscillating magnetic fields produced by small Helmholtz coils placed around the neck and on the head of the pigeon or by larger Helmholtz coils surrounding the cage of the birds. In both types of treatment, which both used a single frequency of about 0-14 Hz, the pigeons’ initial orientation was strongly affected when the oscillation of the artificial magnetic field was square-shaped, whereas a triangular or sine-shaped variation had no effect.

The homing behaviour of pigeons reared in cages with only one side screened to the wind was investigated. It was found that the screening strongly affects the initial orientation of the birds which, when released, tend to fly towards a direction intermediate between home and the direction opposite to the screened side of their home loft. The induced compass preference seems to be related to the amount of wind perceived inside the home loft.The effect is also present when the screens are made of opaque materials, in order to avoid sun light reflections. The induced orientational bias shows a high degree of plasticity: it can be modified in an appreciable way by transferring groups of pigeons into lofts screened on different sides.

The authors report data on initial orientation of laughing doves (Streptopelia senegalensis) and black-billed wood doves (Turtur abyssinicus) displaced to sites, on land and at sea, 1-40 km from their home ground which was near the coast, in the area of the ORSTOM Ornithological Station of Mbour, Senegal. On the whole, the birds did not show the stereotyped directional tendencies often reported in studies on wild birds, but tended to be oriented in directions ap propriate for reaching the ground area; this was especially the case of the black-wood dove.

Systematic observations on seasonal incidence of the red admiral (Vanessa atalanta L.) in central-northern Italy were made in the course of four successive years. Our data show that our region is characterized by regular bidirectional migration which is particularly remarkable in October, during autumn migration to the overwintering sites. Red admirals' migration is highly directional: individuals fly along straight lines at the mean speed of 14 km/h, and produce highly oriented distributions of their vanishing bearings. This directional preference is not the result of passive displacement caused by winds, but is the expression of an internal tendency based on the use of a compass mechanism. Red admirals' seasonal incidence in our area significantly differs from that reported for the northern range of this butterfly species. This study constitutes the base of a long-term investigation aimed at clarifying the phenology and other aspects of migration of this butterfly species (origin and destination of migrants, mechanism of orientation) which, despite the amount of literature on this subject, are as yet not entirely understood.

Experiments were carried out with anosmic Cory's shearwaters to verify whether these birds, which are strictly nocturnal in their activity on land, use olfactory cues to localize individual nest burrows. Both the experimental birds, subjected to intranasal injection of zinc sulphate solution, which produces a reversible impairment of the olfactory mucosae, and unmanipulated controls were captured at their breeding colony on the island of Linosa (Pelagian Islands, Italy). Releases were carried out on the coast nearly 2 km away from the breeding colony. Recoveries at the nests showed that experimentals achieved significantly poorer homing success than controls. The view that the birds were disturbed in a non-specific way by experimental manipulation is weakened by the fact that injection of the same zinc sulphate solution into the coanae, a method only marginally involving the olfactory receptors, does not influence homing behaviour. Our results indicate that in Cory's shearwaters the search for individual burrows is based on, or at least complemented by, olfactory cues.

Twelve series of releases performed with first flight pigeons reared in four Italian lofts are reported. The presence of preferred compass directions (PCDs) in the initial orientation of the birds is clearly evident, even if less pronounced than in other countries. Young birds show initial bearings which are less homeward oriented and more polarized towards a PCD than do older pigeons.