Climate change is for, and against, the birds, say scientists

Use of the phrase "going south for the winter" may soon dwindle, along with disadvantaged southern bird populations.

Research published Friday in the journal Science shows a far-reaching link between climate change and bird populations in the United States and Europe. The findings suggest certain bird species did significantly better over a 30-year period than others. 

The study, led by scientists from Durham University, is the first to demonstrate the link between bird populations and climate change is widespread, even across continents.

That’s bad news for biodiversity, lead author and Durham University biologist Dr. Stephen Willis told The Christian Science Monitor in a phone interview. 

The scientists behind the study began by classifying bird species into two groups.

Mathematical models were produced to show the relationship between specific bird populations and the types of climate where they lived. These models were then compared to year-over-year climate change data ranging from 1980 to 2010.

Bird populations that were living in regions with a climate that had changed to be less suitable for the species were classified as "disadvantaged." Bird populations that lived in regions that were becoming more favorable to their species were marked as "advantaged."

The team then consulted an independent database for population data on 145 common bird species in Europe and 380 in the US. The records showed climates played a significant role in population growth.

"There was a strong signal that those species for which we predicted climate change would be advantageous... on average were doing better than the group of species for which we predicted the climate was getting less suitable," Willis told The Monitor. 

The American robin, for example, had populations decline in southern states, where scientists predicted the climate would change unfavorably. However, in north-central states, where climate was expected to change favorably, the robin populations increased.

The same pattern of northern population increases and southern population decreases were seen in Europe as well.

The gap between the advantaged and disadvantaged populations was also found to be widening, according to the study.

But finding such a clear correlation between animal populations and climate change could be good news for scientists and policymakers working to implement policies to limit the damage of global warming.

The compiled data is a clear line on a year-to-year graph that shows the extent to which those two different species, advantaged and disadvantaged, are being impacted by climate change in each area.

"That could be a tool for lobbying to try and mitigate climate change from increasing in the future in terms of impact," Willis said.

The model could also be a tool for measuring how effective climate change policies are. For instance, it could monitor whether implemented policies result in "those two different groups...starting to behave similarly again and not have these diverging fates for these populations," he added.