Among the movements of animals across the surface of our planet, the wide-r
anging migratory journeys of birds and the smaller-scale foraging excursion
s of social (hymenopteran) insects provide some of the most intriguing exam
ples of biological systems of navigation. Many sensory cues have been found
to be involved in accomplishing these tasks, but how this sensory informat
ion is integrated into the animal's overall system of navigation has remain
ed elusive. Several over-arching concepts such as sun- or star-based system
s of astronavigation, E-vector-based spherical geometry, map-and-compass an
d bi-coordinate position-fixing schemes have been developed to account for
the animals' performances. Although these metaphors have some heuristic val
ue, they are potentially distracting and might obscure some of the most imp
ortant computational strategies used by the brain. Moreover, these top-down
approaches are especially inappropriate in trying to understand the evolut
ionary design of an animal's navigational system. Instead, we must go back
to basics, use modern recording technology to unravel the detailed spatial
and temporal structures of migratory routes and foraging trajectories, stud
y the animal's sensory and computational abilities by combining behavioural
and neurophysiological, approaches, then work bottom-up, as volution did,
by trying to integrate the individual navigational methods. Rather than bei
ng part of a general-purpose navigational toolkit, the various guiding mech
anisms have most certainly arisen from an opportunistic grafting of particu
lar special-purpose modules on to pre-existing sensory-motor control system
s.