A new study published by a team of European researchers have followed the movement of butterflies and birds in relation to a warming European climate. It found that butterflies are responding quicker to the climate than birds – a worrying trend if butterflies and caterpillars move out of the range of the birds during breeding time.
The researchers looked at data from the last 20 years and found that birds and butterflies responded to changing summer temperatures differently. Over the last 20 year warmer temperatures had moved north by 250 kms. [pullquote]A worrying aspect of this is if birds fall out of step with butterflies, because caterpillars and insects in general represent an important source of food for many birds.[/pullquote]
Butterflies moving north faster than birds.
In response to this northward movement of temperatures the butterflies had migrated northwards up to 114 km. The birds though had only moved north by up to 37 kms.
“Both butterflies and birds respond to climate change, but not fast enough to keep up with an increasingly warm climate. We don’t know what the long-term ecological effects of this will be”, says Åke Lindström, Professor of Animal Ecology at Lund University, Sweden.
“A worrying aspect of this is if birds fall out of step with butterflies, because caterpillars and insects in general represent an important source of food for many birds”, explained Åke Lindström.
Butterflies more able to adapt to changing climate.
The researchers explained that the movement differences between butterflies and birds could be explained by 2 main reasons:
- Butterflies have much shorter life cycles and can adapt quicker to changing circumstances.
- Birds prefer to return to previous nesting sites each year for breeding. This means there is a greater inertia within bird populations that prevent the adaptation to changing climate.
One of the countries that was studied for the researcher was Sweden. While the country had little butterfly data available it did show one of the biggest movements of birds in response to temperature change.
More bird species expected in Sweden due to warming environment.
In Sweden the brunt of the warming environment has - as would be expected – been taken by cold climate species such as chaffinches and reed buntings. Those species that prefer warmer climates, such as blackcaps and goldfinches, have seen their numbers increase.
While some cold environment species have been lost to Sweden other warmer climate species have been discovered in the country.
“Over the past 50 years the main factors affecting bird and butterfly numbers and distribution have been agriculture, forestry and urbanisation. Climate change is now emerging as an increasingly important factor in the development of biodiversity”, says Åke Lindström, continued “For Sweden, this will probably mean more species of bird in the long run; many new species are already arriving from the continent.”
Seven countries took part in the study covering Spain, France, the Netherlands, Sweden, the UK, Finland and the Czech Republic.