Feb. 21, 2013 — Common swifts climb to
altitudes of up to 2.5 km both at dawn and dusk. This unexpected behaviour was
discovered by geo-ecologist Dr Adriaan Dokter of the University of Amsterdam's
(UvA) Institute for Biodiversity and Ecosystem Dynamics (IBED) together with
colleagues from the Royal Netherlands Meteorological Institute (KNMI), the
Royal Netherlands Air Force and Lund University.
The research results were published as a
featured article in the March issue of the scientific journal Animal
Behaviour.
In the summer, swifts make their presence felt
in the city, especially because of the screaming sound they make. These common
urban birds appear to have unusual movement patterns. Besides a short breeding
period under urban roofing tiles, these birds spend all year on the wing:
foraging, mating and even sleeping are all performed in flight. Using a novel
radar technique, Dokter and his colleagues studied the nocturnal flight
behaviour of the common swift with the assistance of a weather radar belonging
to the KNMI.
Dokter explains: 'We always assumed that common
swifts ascended in the evening as part of their sleeping cycle. However, now
that we have observed the bird perform ascents at both the start and the end of
night-time periods, this interpretation seems to be incorrect. The ascents must
have a different function, with the birds making use of the unique
opportunities offered by the twilight period.'
No comments:
Post a Comment