January
10, 2019, Cell Press
Researchers
have found yet another way in which climate change has been detrimental to
migrating birds. As European winters have become warmer, pied flycatchers
traveling from Africa over long distances to reach breeding grounds in the
Netherlands are arriving to find that resident great tits have already claimed
nesting sites for the season. As a result, the number of flycatchers killed in
great tit nests has risen dramatically. The work appears January 10 in the
journal Current Biology.
"When
pied flycatchers and great tits are more synchronous in their timing, this
leads to a higher level of conflict over nesting sites," says Jelmer
Samplonius, who did the work at the University of Groningen, the Netherlands,
and is now at the University of Edinburgh, UK.
Samplonius's
team got interested in the dynamics between pied flycatchers and great tits in
part because both species rely on a short burst of food
resources—caterpillars—to raise their young. When the birds' timing is well
matched with the caterpillar peak, they are more successful in raising their
offspring.
Given the
reliance on the same food and nesting resources, it was clear the two species
interacted quite a bit. Pied flycatchers were known for trying to take over
great tit nests. They also eavesdropped on resident great tits to gain
information the long-distance migrants otherwise lack about local conditions.
After
years of careful monitoring, Samplonius says, "it was hard not to
notice" that many flycatchers were dying in great tit nests. In other
years, "virtually none" met that same fate. Could synchrony between
the two competitor species explain the variation?
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