Scientists studying migratory birds in Europe have found that people in the UK feeding their feathered friends has resulted in at least one group of avians taking the first steps to becoming a new species.
Writing in Current Biology, Freiburg University's Gregor Rolshausen and his colleagues studied the Central European blackcap (Sylvia atricapilla), which mates in central Europe and, traditionally, migrates during winter to Spain. But in recent years, lured by generous offerings put out by UK householders, a subset of the birds have developed an alternative migration to Britain, 1800km north of where they should be.
In fewer than 30 generations, the researchers have found, the birds taking this alternative route have already begun to look different to their more southerly-favouring colleagues; they have rounder wings and narrower beaks, probably, say the scientists, because "these birds feed on food provided by humans instead of fruits as the birds that migrate southwest [to Spain] do. As a consequence they have rounder wings, which provide better manoeuverability but make the less suited for long distance migration."
These changes are genetically driven, as is the tendency to migrate to a different location in winter. Intriguingly this suggests that new species can arise side-by-side without the necessity of some kind of geographical barrier.
The team also point out that their study, in which they trapped and studied over a 2 year period migrating birds arriving at their breeding grounds in Germany, illustrates the profound impact of human activities on the evolutionary trajectory of populations.