Point of decision: when do pigeons decide to head home?

Abstract

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.

Waiting time before release increases the motivation to home in homing pigeons (Columba livia)

“…Therefore, we can suppose that this cannot reduce below a certain threshold. However, the reduced time and flight path in the start zone evidenced in our results are in accordance with the hypothesis of a motivational and social component influencing this initial phase, not excluding the orientation function (Dell'Ariccia et al, 2008;Schiffner and Wiltschko, 2009;Wiltschko et al, 2007). The time spent in the start zone is dependent on the flight speed and on the flight path length.…”

“…Pigeons, when released, spent some time flying around the release point, or just nearby, before heading home (Matthews, 1951;Schiffner and Wiltschko, 2009). This initial phase of flight has been mainly explained as a gathering of navigational information at the site (Biro et al, 2002;Spott, 1993) or a technical preparation to the flight (Schiffner and Wiltschko, 2009). Therefore, we can suppose that this cannot reduce below a certain threshold.…”

“…Despite this anecdotal knowledge, a systematic scientific research on this topic is missing. However, motivation to home, acting as a behavioural factor, can have a significant influence on homing and orientation performances of pigeons, as has been recently suggested in the discussion of some results (Biro et al, 2002;Dell'Ariccia et al, 2008;Schiffner and Wiltschko, 2009).…”

“…Immediately after release, most pigeons first circle for some time around the release sites in a radius of about 1 km before choosing a flight direction (Matthews, 1951;Biro et al, 2002;Schiffner and Wiltschko, 2009). We consistently observed that during a series of releases, the last released pigeons headed home more rapidly and circled less around the release site than the first released pigeons.…”

“…Although it seems clear that circling time has a social and motivational component (Dell'Ariccia et al, 2008;Schiffner and Wiltschko, 2009;Wiltschko et al, 2007), the rapid vanishing of late-released birds could reflect improved adaptation to local navigation cues. Using GPS tracking enables the assessment of both the flight behaviour around the release site and the navigational efficiency during the entire flight home.…”