Point of decision: when do pigeons decide to head home?
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Pigeons released away from their loft usually fly around at the release site for a while before they finally leave. Visual observations had suggested that the moment when the birds decide to head home is associated with a certain change in flying style. To see whether this change is also reflected by GPS-recorded tracks, a group of pigeons equipped with flight recorders was released at two sites about 10 km from their home loft. The initial part of their flight paths was analyzed in order to find objective criteria indicating the point of decision. We selected the highest increase in steadiness as the best estimate for the moment of decision. This criterion allows us to divide the pigeons’ paths in two distinct phases, an initial phase and the homing phase, with the moment of decision, on an average, 2 min after release. The moment of decision marks a change in behavior, with a significant increase in steadiness and flying speed and headings significantly closer to the home direction. The behavior of the individual birds at the two sites was not correlated, suggesting no pronounced individual traits for the length of the initial phase. The behavior during this phase seems to be controlled by flight preparation, exploration, and non-navigational motivations rather than by navigational necessities alone.
KeywordsGPS-recorder Flight tracks Steadiness of flight Homing pigeons C. livia f. domestica
Our work was supported by the Deutsche Forschungsgemeinschaft (grant to R.W.) and the Freunde und Förderer der J. W. Goethe-Universität Frankfurt am Main. We sincerely thank B. Siegmund and the students A. Kristoff, R. Savanatan, and F. Wicker for their valuable help with the releases, and an anonymous referee for stimulating and helpful suggestions. The experiments were performed in accordance with the rules and regulations of animal welfare in Germany.
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