Familiar route loyalty implies visual pilotage in the homing pigeon

Abstract

Wide-ranging animals, such as birds, regularly traverse large areas of the landscape efficiently in the course of their local movement patterns, which raises fundamental questions about the cognitive mechanisms involved. By using precision global-positioning-system loggers, we show that homing pigeons (Columba livia) not only come to rely on highly stereotyped yet surprisingly inefficient routes within the local area but are attracted directly back to their individually preferred routes even when released from novel sites off-route. This precise route loyalty demonstrates a reliance on familiar landmarks throughout the flight, which was unexpected under current models of avian navigation. We discuss how visual landmarks may be encoded as waypoints within familiar route maps.

Fig. 1.

Flight tracks recorded from nine homing pigeons from a variety of release sites. (A) Shown are flights of individual subjects (birds 1–9) from Weston Wood and its vicinity. (B) Shown are flights by the same birds from High Cogges and its vicinity. Light blue circles indicate the location of the training release sites. Blue tracks correspond to subjects' final three training flights; red tracks show four subsequent off-route test releases (location of off-route sites marked by orange circles). Bird 9 failed to home on its second release from High Cogges and is thus missing from B; bird 5 disappeared after its second off-route test release from the High Cogges area. Location of home is indicated by a white dot. (Scale bars, 2 km.) [Map image copyright 2004, Crown Copyright Ordnance Survey, an EDINA Digimap/Joint Information Systems Committee (JISC) supplied service.]

Fig. 2.

Circular diagrams showing changes in flight trajectory upon birds' first contact with their established routes during off-route test releases at Weston Wood (A) and High Cogges (B). Triangles indicate angular deviations in individual off-route trajectories before and after initial contact with the same bird's established route (open triangles correspond to tracks for which birds approached their established routes from the right, and filled triangles correspond to tracks for which they approached them from the left). Circles indicate angular differences between the established route and the off-route trajectory after initial contact (open and filled circles are distinguished as above according to direction of approach). Arrows show mean vectors for angular deviations in precontact versus postcontact off-route trajectories (solid arrows) and postcontact off-route versus established route trajectories (dashed arrows); filled arrowheads denote left approach and open arrowheads denote right approach. See text for further detail.