Adapting to changing climate proving tricky for Europe's birds
Birds are finding it increasingly difficult to adapt to Europe's warming climes. That is the warning from a pan-European group of researchers in a major new study published in the journal Nature Climate Change. The study, which received funding from four different EU-funded projects, brings together scientists from the Czech Republic, Germany, Spain, France, the Netherlands, Finland, Sweden, and the United Kingdom.
Over the past two decades, Europe's climate has been getting steadily warmer, and set temperatures have shifted northwards by 250 km, making life unbearable for species of bird and butterfly which thrive in cool temperatures. Yet the study finds that the bird and butterfly communities have not moved at the same rate as the temperatures.
For the study, birds were divided into two groups, depending on whether they thrive in slightly 'colder' or 'warmer' climates. For example, chaffinches and reed buntings are 'colder' species, while blackcaps and goldfinches are 'warmer' species.
The study was funded as part of the EU's STEP ('Status and trends of European pollinators') project, which was boosted by a grant of some EUR 3.5 million under the 'Environment' Theme of the Seventh Framework Programme (FP7). Funding also came from the CLIMIT ('Climate change impacts on insects and their mitigation') project, part of the ERA-Net BiodivERsA2 network, funded in part by almost EUR 2 million under FP7's 'Coordination' Theme.
The study also received a boost from two Sixth Framework Programme (FP6) projects: ALARM ('Assessing large-scale environmental risks with tested methods') which received just under EUR 13 million of EU funding under the programme's 'Sustainable development, global change and ecosystems' Thematic area; and MACIS ('Minimisation of and adaptation to climate change: Impacts on biodiversity') which was funded to the tune of EUR 900 000 under the 'Research for policy support' Thematic area.
After analysing 20 years’ worth of data on birds, butterflies, and summer temperatures, the team concluded that some birds and butterflies have difficulty adapting quickly enough to the warmer climate. For many of these species, attempts at moving further north have for the most part been unsuccessful.
One of the study authors, Professor Åke Lindström from Lund University, Sweden, comments: '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.'
Butterflies have adapted more quickly to the changing temperatures, and have moved on average 114 km north, whereas birds have only moved 37 km. The researchers suspect that this difference can be attributed to the butterflies' shorter lifespans that make it easier for them to adapt quickly to climate change. As birds like to return to the same breeding ground year in year out, they show more resistance to changing behaviour patterns.
However, this two-tier adaptation process could pose problems for birds, as Professor Lindström explains: '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.'
The team were able to measure which birds were moving where by looking at which 'colder' and 'warmer' birds appear in which areas. They quantified the yearly change in community composition in response to climate change for 9 490 bird and 2 130 butterfly communities distributed across Europe.
'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 Professor Lindström.