Date: February 25, 2019
Source: University of Helsinki
Summary:
According
to a new study, migratory birds in Europe and Canada have substantially
advanced the timing of their spring migration due to climate change. The
average migratory bird has advanced its spring migration by approximately one
week in five decades, and the duration of the migration season has increased.
The
greatest advances were found among short-distance migrants that winter in
Europe or North America: about 1.5-2 days per decade. Long-distance migrants
that winter in the tropics have also advanced the start of their migration, but
only by approximately 0.6-1.2 days per decade.
"Based
on changes in median migration dates, birds have on average advanced their
spring migration by a little over a week since the late 1950s," says
Aleksi Lehikoinen from the Finnish Museum of Natural History, University of
Helsinki.
Some
species show much greater advances. For instance, Whooper Swans now arrive in
Finland about two weeks earlier than in the 1980s.
The
advances in spring migration dates are not equal across the migration season.
Early migrants of a given species have advanced their migration dates more than
late migrants within the species' migration season. First migrants have the
highest pressure to arrive at their breeding grounds as early as possible,
whereas late migrants are typically non-breeders, which have no rush to move
north. This asymmetry has led to an overall increase in the duration of
migration.
