Scientific
American
Harald Franzen
 Global
warming may have yet another negative side effect: it could disrupt birds' breeding
patterns and subsequently reduce their numbers considerably, according to a new
study published in today's Science.
The rise in global temperature is
likely to change the normal turn of seasons such that spring will arrive earlier.
Although this may seem appealing at first, an earlier spring might come without
the familiar chriping of birds. Indeed, the warmer weather could lead some birds
to breed earlier in the year when food is not as readily available. Fewer birds
would breed and fewer would survive.
To test this hypothesis, a team of
scientists from Canada, France and the U.K. took a closer look at two populations
of tiny blue tits called Parus caeruleus (see image) in southern France and on
the island of Corsica. They discovered that whereas the birds on Corsica bred
at the time when caterpillarsÑa ready food sourceÑwere most plentiful, the birds
on the mainland were out of sync. They bred several weeks before the caterpillar
population reached its peak. This relative food shortage made it more difficult
for the mainland blue tits to rear their young and thus reduced the number of
breeding adults overall. |
