Seasonal migration patterns in Eurasian blackcaps

New research from the University of Oxford has found unexpected migration patterns in the Blackcap, an iconic European bird species: while most of us would prefer to spend the winter somewhere warm and sunny, many of these small birds fly north every year. 

Our planet is changing, and so too are the migrations of birds that crisscross its hemispheres. Shifting climates and landscapes have caused many species to modify where they go, when they depart, and even if they migrate at all. Research published in Proceedings of the Royal Society B sheds new light on the migrations of the Blackcap, including the surprising origins of a new wintering population in Britain.  

Researchers from over a dozen institutions, including the University of Oxford, British Trust for Ornithology, and Max Planck Institute, tracked 100 Blackcaps across Europe to understand their changing migration patterns. Although few Blackcaps spent the winter in Britain prior to 1960, they are now a common winter visitor—a change that has been linked to climate change and garden bird feeding. 

The researchers discovered that Blackcaps wintering in Britain do the opposite of most other European bird species: they fly north for the winter. These birds arrived from France, Spain, Germany, and other continental European countries to spend the winter in Britain. 

Why risk the cold? The study found that Blackcaps wintering in Britain returned to their European breeding areas 10 days earlier in spring than those wintering further south, which may provide an evolutionary advantage by allowing them to access the best breeding sites.

“Past experiments with Blackcaps form the foundation of our understanding of bird migration, but they were primarily done in the 1990s, before today’s golden age of tracking technology,“ says Benjamin Van Doren, a primary author on the study from the University of Oxford. “It is incredibly exciting to finally track these birds in the wild.”

The study also found that Blackcaps breeding in central Europe changed migratory directions over a surprisingly short distance. In autumn, Blackcaps in western Europe migrate southwest and those in eastern Europe migrate southeast. The scientists identified an area in Austria only 27 km wide where the transition from southwest to southeast directions occurs. They say that this pattern indicates a strong evolutionary advantage to using the proper direction.

For the researchers, these findings are only the beginning, a stepping stone to unlocking the mysteries of bird migration. “Our study lays the groundwork for genomic research with these same birds, where we hope to identify the genes that control where they go and when they migrate,” says Van Doren.

Read more here.