A study
led by Nebraska's Robert Zink proposes that many bird species, such as the
Canada warbler, may have completely stopped migrating during the last ice age.
The onset
of the last ice age may have forced some bird species to abandon their
northerly migrations for thousands of years, says new research led by a
University of Nebraska-Lincoln ornithologist.
Published
Sept. 20 in the journal Science Advances, the study challenges a long-held
presumption that birds merely shortened their migratory flights when glaciers
advanced south to cover much of North America and northern Europe about 21,000
years ago.
The study
concluded that the emergence of glaciers in those regions instead acted as an
“adaptive switch” that turned off migratory behavior, transforming the tropics
from a cold-weather resort into a long-term residence for certain bird species.
Of the 29
long-distance migrant species examined in the study, 20 likely saw their
northern breeding grounds become uninhabitable, according to models developed
by the researchers. When the climate again warmed and glaciers retreated back
to the Arctic, those species presumably resumed their seasonal migrations.
Lead
author Robert Zink said the conclusions could alter how scientists reconstruct
the history of bird migration.
“It fundamentally
changes the way we study the evolution of migration and think about the
migratory behavior of birds,” said Zink, professor of natural resources and
biological sciences at Nebraska.
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