Yellowhammer birds were introduced from Britain to New Zealand in the 1860s, where they have now become a pest. But it seems some bird song dialects that have gone extinct in the UK still persist in the birds introduced to the antipodean nation during the Victorian era.
“This phenomenon of lost birds’ dialect is an avian equivalent of what happens with human languages,” says lead author Pavel Pipek, from Charles University in Prague, in a statement. “For example, some English words, which are no longer spoken in Great Britain, are still in use in the former British colonies.
He added: "It was fascinating to have this unique opportunity to study yellowhammer dialects from native and introduced populations and how they have evolved over 150 years.”
The study of the birds down under utilized the role of the citizen scientist. By using recordings that members of the public had taken of the birds, both audio and video, they were able to build up a library of the vocalizations and dialects the birds use across the country. From this, they could then compare it to how the birds back in their native land sing and see where the differences lie.
In the study, published in Ecography, they found that the yellowhammers in New Zealand had a much wider repertoire of dialects that those in Britain – in fact, almost twice as many, which surprised the researchers. They expected that the native birds would have had a wider range when compared to those introduced, simply because those in New Zealand would have seemingly gone through a bottleneck.
They think that while the 600 or so introduced birds retained their original song structures, at least in some populations, those that remained in the motherland lost many. This, the researchers suggest, is probably down to the fact that yellowhammer numbers in the UK have plummeted, and as they have vanished from the farmlands, they have taken some of their dialects with them.
“At one time they were a common sight, but sadly their numbers have declined so rapidly that nowadays they are difficult to find in many parts of the UK,” says Dr Mark Eaton, RSPB principal conservation scientist and study co-author. “It’s likely the decline in yellowhammers has led to some of their original dialects being lost yet these have survived in the songs of the birds in New Zealand due to the abundant populations.”
The tune of the New Zealand yellowhammers may therefore act in effect as a living archive of what the British countryside sounded like over 100 years ago.