Data from: Non‐breeding flight activity in pallid swifts Apus pallidus

Flight activity recorders have recently confirmed that alpine and common
swifts spend the majority of their non‐breeding period on the wing, which
may last 6‐10 months. Here we test the hypothesis that the closely related
pallid swift, a species with a breeding distribution around the
Mediterranean, lead a similar aerial life‐style during its migration and
wintering periods. The pallid swift usually lays two clutches in one
season and therefore spends more time in the breeding area than the common
swift. We successfully tracked four pallid swifts with data loggers that
record light for geolocation and acceleration every 5 minutes to monitor
flight activity. The birds wintered south of the Sahel in West Africa from
the Ivory Coast to Cameroon. The pallid swifts spent the majority of their
non‐breeding time in flight, especially the first two months after leaving
the breeding area in autumn, while a few landing events occurred during
the winter. The total time grounded was <1%, similar to that of the
common and alpine swifts. The mass specific flight metabolic rate of
swifts is similar to the average non‐breeding metabolic rate of a long
distance terrestrial migrant, suggesting swifts are not more likely to
procure oxidative damage as a consequence of continuous flight than other
migrants. The open airspace used by swifts may provide a relatively safe
habitat that explain the high survival rate found in swifts.