BRANTA — Jacqueline Chappell
The psychology of homing pigeon navigation
Institution: University of Oxford, UK
Supervisors: T Guilford
Details: DPhil 1996 (Completed)
Address: School of Biosciences, University of Birmingham, U.K. (Oct 2005) Email
Subject Keywords: navigation, sun compass, spatial learning, pigeon, orientation
Species Keywords: Homing pigeon Columba livia
Abstract
Recent experiments have shown that pigeons (Columba livia) use visual landmarks in homing from a familiar site, but the exact role of landmarks in the familiar area map is still unknown. In this thesis, the mechanism of visual landmark use is investigated using an open-field arena food-finding task. The arena allows landmarks to be manipulated independently of the sun compass. Pigeons appeared to rely primarily on the sun compass outdoors to locate the direction of a target goal, rather than prominent two-dimensional visual cues. However, similar experiments indoors, where the sun compass was unavailable, suggested that this reliance may have been due to a specific lack of salience in the two-dimensional visual cues provided. Pigeons were unable to locate the target goal consistently indoors when only two-dimensional cues were present and they had no view of the experimental room, but they were able to perform the task when a three-dimensional cue was added. The addition of the same three-dimensional cue outdoors reversed the reliance on the sun compass: pigeons now relied primarily on the visual cues rather than the sun compass to locate the target goal. These results suggest that pigeons may have two strategies available within their familiar area, depending on the type of landmarks available: they can use visual landmarks directly to locate the home direction, or they can use the visual landmarks merely as a label to which a sun compass bearing is attached.
These results also revealed that the clock-shift group was more directionally scattered than the control group, and showed a smaller deflection than would theoretically be expected. These are common findings of experiments involving clock-shifting pigeons in outdoor release experiments. The results of these published experiments were analysed to try to determine the cause of these effects. This analysis suggested that the clock-shift effects were probably due to conflict between the sun compass and either the magnetic compass or visual landmarks, rather than being an effect of the process of clock-shifting itself.
Finally, experiments exploiting pigeons’ alleged ability to recognise real locations pictured in colour slides could potentially be a useful tool in investigating the mechanisms of landmark use. However, results from these published experiments have been conflicting. Y-maze experiments revealed no evidence that pigeons were even able to transfer a colour discrimination from colour slides to real objects (or vice versa). This suggests that experiments involving the transfer of a discrimination from colour slides to real objects should be interpreted with caution.
These results suggest a complexity in pigeons’ use of visual landmarks in the familiar area that might not have been revealed using conventional release experiments.
Published Papers
Chappell, J. & Guilford, T. 1997. The orientational significance of visual cues to the homing pigeon. Animal Behaviour 53: 287-296.
Chappell, J. & Guilford, T. 1995. Homing pigeons use the sun compass rather than fixed directional visual cues in an open-field arena food-searching task. Proceedings of the Royal Society of London, Series B 260:59-63
Chappell, J, 1997. An analysis of clock-shift experiments: is scatter increased and deflection reduced in clock-shifted homing pigeons? Journal of Experimental Biology 200: 2269-2277.
Wallraff, H.G., Chappell, J. & Guilford, T. 1999. The roles of the sun and the landscape in pigeon homing. Journal of Experimental Biology 202: 2121-2126.