Wednesday, 15 January,
2003, 11:29 GMT
Climate changes disrupt
birds
Shifts in spring temperatures in central Europe may be having a significant
effect on the ability of birds to breed successfully, say scientists.
While the full impact of climate change is not yet clear, some birds
whose populations rely on hatching two clutches of eggs a year may
be hit hard.
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The
research, covering two decades of data and published in a journal of
the Royal Society, looked at populations of great tits (Parus major)
and blue tits (Parus caeruleus).
However, the researchers said that these species were representative
of many other common European birds. |
Blue tits: Breeding
habits have changed
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Food shortage
Obviously, the birds choose spring because
it is the time of year with an abundance of suitable food - in this
case caterpillars and suchlike.
However, a warmer spring hastens the development of the caterpillars,
meaning there is a shorter period before they become butterflies or
moths.
This means there may be insufficient food to support two broods in a
single spring.
The researchers found that in areas in which "double-brooding"
was commonplace, the move was towards single brooding.
And in areas in which birds only produced one brood, the timing of egg-laying
tended to be earlier.
This, said the researchers, was clear evidence that climate change was
having an impact.
Wait and see
Dr Marcel Visser, from the Netherlands Institute of Ecology, said many
factors would influence whether there would be an adverse impact on
bird populations over time.
However, he said it was likely that a move from "double-brooding"
to single clutches would not be beneficial.
He states: "Climate change is changing all these populations of
birds.
Obviously, the warmer winters might mean that more of the birds are
likely to survive through the winter."
"What we are trying to find out now is whether these birds are
likely to adapt to the changes."
John Lanchberry, head of climate change at the RSPB, says that he would
expect to see more opportunistic species moving into new areas further
north.
However, he added: "They can only do this if the food is there
for them to eat.
"The danger is if different species move at different rates - you
could end up with a different ecosystem."
source: http://news.bbc.co.uk |
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