Pigeons combine compass and landmark guidance in familiar route navigation

Abstract

How do birds orient over familiar terrain? In the best studied avian species, the homing pigeon (Columba livia), two apparently independent primary mechanisms are currently debated: either memorized visual landmarks provide homeward guidance directly, or birds rely on a compass to home from familiar locations. Using miniature Global Positioning System tracking technology and clock-shift procedures, we set sun-compass and landmark information in conflict, showing that experienced birds can accurately complete their memorized routes by using landmarks alone. Nevertheless, we also find that route following is often consistently offset in the expected compass direction, faithfully reproducing the shape of the track, but in parallel. Thus, we demonstrate conditions under which compass orientation and landmark guidance must be combined into a system of simultaneous or oscillating dual control.clock shift ͉ homing pigeon ͉ sun ͉ pilotage ͉ route recapitulation S equential use of a map for position fixing and a compass for onward guidance has long been regarded as the fundamental model characterizing avian navigation (1, 2). Although there continues to be disagreement over the details, it is generally accepted that over unfamiliar terrain olfactory signals are used to cue position, and a solar or magnetic compass is used to guide orientation home (reviewed in ref. 1). Curiously, much less is known about what happens when birds reach familiar terrain. Current evidence suggests that pigeons reduce dependence on navigating by atmospheric chemosignals, and instead use the memorized landscape to determine their position with respect to home (1). Nevertheless, there are two competing hypotheses for how homeward orientation is then controlled. The first hypothesis, sometimes called ''pilotage'' (2, 3), suggests that guidance is compass-independent and involves orienting directly by the pattern of visual landmarks. The second hypothesis, sometimes referred to by the term "mosaic map" (4) by some authors (5), suggests that guidance between familiar locations is compass controlled just as it is from unfamiliar locations (6). Current evidence is equivocal (7,8). We have previously shown that with extensive local experience homing pigeons come to rely on highly stereotyped, individually distinct flight paths (and that this faithful route-following does not require the magnetic compass; see ref. 9). Birds displaced off route usually return directly to their memorized path, implicating direct attraction to visual landmarks (10). Nevertheless, clock-shift experiments, which attempt to alter the pigeon's dominant time-compensated suncompass, indicate that compass orientation may be used even from familiar release sites (8,(11)(12)(13)(14)(15)(16)(17)(18)(19). Thus the role of the sun-compass remains substantially unresolved, with inferences largely dependent on classical vanishing data which can only provide partial information on a bird's navigational decisions. Using miniature precision Global Positioning System (GPS) logging technol...

Route following and the pigeon's familiar area map

“…2). Since its original discovery, route following has been demonstrated or visualised in published experiments from at least 13 different sites and at distances of up to 25 km from the home loft (Armstrong 2010;Biro et al, 2004;Biro et al, 2006a;Biro et al, 2006b;Biro et al, 2007;Flack et al, 2012;Pettit et al, 2013). Route following was also suspected, but Route following and the pigeon's familiar area map Tim Guilford* and Dora Biro not explicitly demonstrated, in a study in the USA (Mora et al, 2012), and discussed as an important part of individual flight behaviour, but not explicitly measured, in a study in Italy (Dell'Ariccia et al, 2008).…”

Hippocampal‐dependent familiar area map supports corrective re‐orientation following navigational error during pigeon homing: a GPS‐tracking study

“…A navigational map enables a pigeon to determine the direction of displacement relative to home from unfamiliar as well as familiar locations. However, over familiar terrain, navigation can be guided by a memory representation of familiar landmarks ⁄ landscape features in addition to the navigational map (Wallraff & Neumann, 1989;Braithwaite & Guilford, 1991;Wallraff et al, 1993;Gagliardo et al, 2001;Biro et al, 2004Biro et al, , 2007. Recently, there has been growing interest in the landmark-based navigational mechanisms that homing pigeons can employ over previously experienced, familiar areas closer to the loft, with an emphasis on visual landmarks ⁄ landscape features (Bingman & Able, 2002;Biro et al, 2002;Wallraff, 2005b;Gagliardo et al, 2007).…”

Flight responses by a migratory soaring raptor to changing meteorological conditions

“…This is because study of flight strategies of birds requires precise spatial data collected at extremely high temporal frequencies [2 -4]. Until recently, research in this area was constrained by limitations of data from short-duration tracking [4 -6], infrequent GPS satellite telemetry [7] or GPS data loggers requiring manual download [3,[8][9][10]. Because large, wary and sparsely distributed birds of prey are difficult to recapture for data logger retrieval and impractical to track over long distances with gliders, there have historically been no tools useful to study the in-flight micro-scale decisions birds make over long distances.…”