Why familiar landmarks often override the compass
When an animal has learned a route, the visual panorama along that route becomes a strong steering signal. In night-active bull ants, landmark guidance was found to dominate over polarised skylight as a compass cue during route following [1]. Desert ants likewise adjust their path according to extended landmarks, and how much they rely on compass cues depends on the state of their global vector—the internal sense of direction and distance built up during the journey [3]. This suggests that landmarks are not just decorative: they can recalibrate or override the compass-derived heading.
Pigeons show a similar pattern. On familiar routes they can navigate using landmarks alone, and their route following integrates compass and landmark information rather than relying on either in isolation [2]. The practical implication is that a memorized visual scene acts as a local map, while the compass supplies a broader directional frame that landmarks can refine or correct.
The compass still sets the frame and fills the gaps
Landmark dominance does not mean compass cues are irrelevant. In bull ants, polarised skylight still provides compass information during night route following, even though landmarks are the stronger influence [1]. In pigeons, compass mechanisms—solar or magnetic—are used to cue position over unfamiliar terrain, where learned landmarks are not yet available [2]. So the compass is most useful when the animal is off its familiar route or when landmarks are absent or unreliable.
This division of labor makes sense: a compass gives a global direction that works anywhere, while landmarks give precise local corrections. The two are combined, but the weighting depends on which cue is more trustworthy in that moment.
Topography and the scale of landmarks change the balance
The size and layout of landmarks matter. Desert ants were tested with an extended landmark larger than those commonly encountered on their terrain, and their path after a barrier was strongly influenced by that visual scene [3]. This indicates that topographic features—the shape and arrangement of the landscape—can act as extended landmarks that guide route following, interacting with habitual compass directions.
In birds, topographical cues are part of landmark-based navigation, and pigeons adopt habitual routes that combine visual topography with compass mechanisms [4]. The scale of the terrain thus affects whether an animal leans more on local topography or on a global compass: large, distinctive features can serve as anchors, while featureless terrain pushes reliance back toward the compass.
Learning and cue ambiguity shape what an animal trusts
Route learning itself changes cue use. As an animal becomes familiar with a route, familiar landmarks can trigger reactions that guide turns, and the question of whether a turn is cued by a landmark or by a place remains central to understanding wayfinding [5]. This means the dominance of landmarks is learned, not innate: it grows with experience on that specific route.
When cues conflict or are ambiguous, the animal's choice reveals its weighting. The evidence suggests that learned landmarks and topography generally take priority in familiar settings, while global compass cues provide the fallback and the overall directional framework [1][2][3]. The exact balance is likely species- and context-dependent, and the studies here do not pin down a single universal rule.
Sources used in this answer
Polarised skylight and the landmark panorama provide night-active bull ants with compass information during route following
Night-active bull ants use both polarised skylight and landmark panoramas for compass information during route following, with landmark guidance dominating.
Pigeons combine compass and landmark guidance in familiar route navigation
Pigeons on familiar routes can navigate using landmarks alone, and route following integrates compass and landmark guidance, with compass cues used over unfamiliar terrain.
The guidance of desert ants by extended landmarks
Desert ants' route following is influenced by extended landmarks, and their reliance on compass cues depends on the state of the global vector.
Landmark-based navigation in birds: learning and using topographical cues
Birds use visual, topographical, and magnetic cues in homing, and pigeons adopt habitual routes that combine landmark and compass mechanisms.
Route learning and wayfinding
Route learning and wayfinding involve reacting to familiar landmarks, and the cue for turning—landmark versus place—remains a central question; topography was not represented in one navigation context.