Data from: Homing pigeons (Columba livia) modulate wingbeat characteristics as a function of route familiarity

Mechanisms of avian navigation have received considerable attention, but
whether different navigational strategies are accompanied by different
flight characteristics is unknown. Managing energy expenditure is critical
for survival, therefore understanding how flight characteristics, and
hence energy allocation, potentially change with birds familiarity with a
navigational task could provide key insights into the costs of
orientation. We addressed this question by examining changes in wingbeat
characteristics and airspeed of homing pigeons (Columba livia) as they
learned a homing task. Twenty-one pigeons were released 20 times
individually from either 3.85 km or 7.06 km from home. Birds were equipped
with 5 Hz GPS trackers and 200 Hz tri-axial accelerometers. We found that,
as the birds' route efficiency increased during the first six
releases, their median peak-to-peak dorsal body (DB) acceleration and
median DB amplitude also increased. This, in turn, led to higher
airspeeds, suggesting that birds fly slower when traversing unfamiliar
terrain. By contrast, after route efficiency stabilised, birds exhibited
increasing wingbeat frequencies, which did not result in further increases
in speed. Overall, higher wind support was also associated with lower
wingbeat frequencies and with increased DB amplitude. Our study suggests
that the cost of early flights from an unfamiliar location may be higher
than subsequent flights both due to inefficient routes (increased
distance) and lower airspeeds (increased time). Furthermore, the results
indicate, for the first time, that birds modulate their wingbeat
characteristics as a function of navigational knowledge, and suggest that
flight characteristics may be used as "signatures" of
birds' route familiarity.