[TN-Bird] Climate change and the timing of nesting of migratory birds
- From: "Charles P. Nicholson" <cpnichol@xxxxxxxxxxxxx>
- To: <tn-bird@xxxxxxxxxxxxx>
- Date: Wed, 10 May 2006 20:35:48 -0400
The British science journal Nature just published a very interesting article
about reduced nest success in the Pied Flycatcher due to the poor synchrony
between the bird's nesting season and the peak in abundance of its dominant
caterpillar food source. The Pied Flycatcher is a migratory European
species which nests in boxes and is among the most-studied birds in the
world.
The article describes what has long been predicted to be a harmful effect of
climate change on migratory birds. With milder winters and earlier springs,
the main flush of insect prey that lots of migratory birds feed to their
nestlings occurs earlier and earlier, and the migratory birds cannot advance
their breeding season fast enough to synchronize with the flush of insects.
Following is the abstract of the article, and then a description of the
study from the AAAS's ScienceNow site.
Rather thought provoking.
Chuck Nicholson
Norris, TN.
Nature 441, 81-83 (4 May 2006)
Climate change and population declines in a long-distance migratory bird
Christiaan Both, Sandra Bouwhuis, C. M. Lessells and Marcel E. Visser
Phenological responses to climate change differ across trophic levels, which
may lead to birds failing to breed at the time of maximal food abundance.
Here we investigate the population consequences of such mistiming in the
migratory pied flycatcher, Ficedula hypoleuca. In a comparison of nine Dutch
populations, we find that populations have declined by about 90% over the
past two decades in areas where the food for provisioning nestlings peaks
early in the season and the birds are currently mistimed. In areas with a
late food peak, early-breeding birds still breed at the right time, and
there is, at most, a weak population decline. If food phenology advances
further, we also predict population declines in areas with a late food peak,
as in these areas adjustment to an advanced food peak is insufficient.
Mistiming as a result of climate change is probably a widespread phenomenon,
and here we provide evidence that it can lead to population declines.
**********************************
Migrating Birds Not Early Enough
By Eli Kintisch
ScienceNOW Daily News
5 May 2006
Some pied flycatchers, a common migratory bird slightly smaller than a
sparrow, are missing their spring meals and dying as a result of climate
change, a team of scientists reported this week. The discovery is one of the
most sophisticated showing the domino effect of shifting seasons and their
impact on predators and prey.
The migratory birds fly thousands of kilometers each spring from wintering
grounds in Africa to Europe, where they breed. In 2001, scientists with the
Netherlands Institute of Ecology found that the flycatchers' reproduction
suffered because they arrived in Europe too late to have much time to breed.
Now, University of Groningen evolutionary ecologist Christiaan Both worked
with scientists from the institute and measured how many caterpillars were
available for the birds to eat by weighing the insects' droppings.
Caterpillars, they learned, have responded to an earlier spring by moving up
their peak emergence by 16 days.
But some of the birds are only breeding a week earlier than they used
to--and their young are consequently missing out on many meals. "It's
impossible for them to predict when the spring starts in Europe," says Both.
That's had a profound impact, the team reported in the 4 May Nature. Among
nine flycatcher populations they studied over 2 decades, the researchers
found that those that mistimed their arrival declined in number by a
stunning 90%, compared to better-synchronized groups that suffered only a
10% drop. Both hopes that genetics will help explain why some pied
flycatchers are leaving Africa sooner. Both is also hoping to begin tracking
birds to see if they are adapting by migrating to European areas further
north.
"It's a really important piece of the puzzle," says Cornell University
ornithologist David Winkler, who reviewed the paper for Nature. "He's adding
detail to the avian response to climate change that we don't have
elsewhere." Scientists are only beginning to learn how climate change alters
the timing of ecological interactions, but many suspect the cross-species
impacts are going to be great. Both's work, Winkler says, suggests that
other studies may be missing the fact that even when the birds migrate
sooner, they might still be missing food or other ecological needs.
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