Immigrants to New Zealand are often quick to pick up our signature twang - but it seems one ex-pat hasn't lost its British accent more than a century after moving here.

That's the yellowhammer, a bird introduced in the 19th century, and which has proven another example of New Zealand's odd role as a "living archive" for introduced species' quirks and traits long lost from their motherland.

A study just published in Ecography examined yellowhammer dialects in the UK and New Zealand, where the birds were introduced in the 1860s and 1870s and later became pests.

It found some dialects that likely existed in the UK appear to have gone extinct, yet they still exist in New Zealand - a phenomenon which also occurs in human languages.

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The research was led by a Czech researchers who encouraged volunteers to collect and submit recordings of singing yellowhammers using smartphones and cameras.

Using these recordings from the citizen science project, scientists compared the patterns of yellowhammer dialects in the native range of Great Britain, and in the invaded range of New Zealand.

Although they expected our yellowhammers to exhibit fewer dialects than those in the mother country, quite the opposite pattern emerged - New Zealand boasts almost twice as many yellowhammer dialects as Great Britain.

New Zealand yellowhammers had seven different dialects - five of which are no longer heard in Britain but have been heard in continental Europe.

The New Zealand yellowhammers were also found to sing a greater number of different dialects.

Experts think the best explanation for their findings is that New Zealand yellowhammers have retained song structures which were originally from the UK.

However, these dialects have subsequently been lost in the mother country, possibly due to the widespread decline in yellowhammers in the UK.

"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," said lead author Pavel Pipek, of the Charles University in Prague.

"This phenomenon of lost birds' dialect is an avian equivalent of what happens with human languages.

"For example, some English words, which are no longer spoken in Great Britain, are still in use in the former British colonies."

British yellowhammers had experienced a severe population decline in recent decades, meaning the original variety of dialects might have diminished.

Co-author Dr Mark Eaton said the birdsong recorded in New Zealand may serve as a living archive of songs sung by yellowhammers in 19th century Britain.

The paper comes after a 2015 study revealed how pest stoats lurking in our wilderness include several genetic types that have long been lost from populations in their native Britain, prompting UK scientists to ask whether this diversity may even be worth bringing back home.

People can get involved in a citizen science project monitoring yellowhammers here.

Yellowhammers in NZ

• The colourful yellowhammer is a common inhabitant of open country throughout much of New Zealand.

• Introduced from Britain by Acclimatisation Societies between 1865 and 1879, it has spread widely, including reaching many off-shore islands.

• Yellowhammers feed on a variety of seeds and invertebrates and are frequently seen feeding on the seeds in hay fed to livestock, and also on newly-sown grass seed.

Source: New Zealand Birds Online