Czechs probe the secret language of birds
It is a well-known fact that there are various dialects in human languages, but not everyone is perhaps aware that the same holds true for birdsong. A new study by Czech scientists has researched the dialects of the yellowhammer, a tiny bright yellow bird of the bunting family, shedding light on the cultural evolution of birdsong. Scientists revealed that the original yellowhammer dialects thought to have gone extinct in Great Britain have survived in birdsong overseas, particularly in New Zealand immigrants.
In a project called Yellowhammer Dialects, a team of Czech scientists focused on the research of the yellowhammer songs. They encouraged volunteers in the UK and New Zealand to collect and submit recordings of yellowhammers using their smartphones or cameras.
They subsequently compared the patterns of yellowhammer dialects in the native parts of Great Britain and in the areas of New Zealand, where the birds were introduced in the mid-19th century, to discover that birdsong dialects evolve in analogy to human languages.
I asked Pavel Pipek, a lead author of the study, if it was common for all bird species to develop dialects in their songs:
“It is true only for several bird groups, such as passerines, parrots and humming birds. You can really trace various dialects in these groups. Similarly to humans, birds learn their vocalization, in this case singing, from their parents and neighbours. So it is not something innate. It is related to various issues, such as migratory strategies. If the species are resident, for instance, it is easier for them to develop dialects. It also depends on how many melodies they can master.”
The history of the yellowhammer dialect research dates back to 2011, when the Czech Society for Ornithology chose Yellowhammer as the Bird of the Year, drawing attention to the fact the populations of farmland birds have been rapidly declining.
Pavel Pipek explains why their next steps led to Great Britain and New Zealand:
“When I realized that the yellowhammers were introduced to New Zealand, it fascinated me that we could compare what happened with their songs after 150 years of complete isolation from the original source. We were interested to see if they managed to retain the dialects from the localities in Great Britain from which they were caught and transported.”
Some 600 yellowhammers were introduced to New Zealand back in the 1860s and 1870s to help local farmers fight with crop pests, namely caterpillars and black field crickets. The native birds were not available to do the job, because they gradually disappeared as the settler cleared away the country’s forests:
“There were big landscape changes taking place in the country at the beginning of the colonization period. New crops were introduces which became plagued by insects. New Zealand farmers wanted to get rid of those crop pests and though it was a good idea to bring birds from England, because they feed their chicks by insects.
“However, their choice was rather unfortunate, because the birds, which were introduced as a biological control against pests, became pests themselves, along with sparrows and green finches. So while the New Zealanders originally imported these birds, in less than 20 years they started to get rid of them with poison and other means of destruction.”
To trace the journey of the yellowhammer birds from the United Kingdom to New Zealand proved to be a detective’s work. Scientists used original documents such as letters, bills and minutes from meetings kept by the so-called Acclimatization Societies, organizations founded especially to introduce new animals and plants to New Zealand. Pavel Pipek again:
Although they expected New Zealand yellowhammers to exhibit fewer dialects than those in the mother country, quite the opposite pattern emerged. Surprisingly, New Zealand boasted nearly twice as many yellowhammer dialects as the United Kingdom.
In one case, Pipek has identified one locality in Brighton, from which birds were shipped to Otago, on the Southern Island of New Zealand. Yet, when they compared the dialects of the yellowhammer the dialect in these two localities, they turned out to be completely different.
“This led us to a simple explanation that probably in the past, these dialects used to exist in Britain and they only disappeared during the recent population decline. Because while in New Zealand Yellowhammers are still thriving, in Great Britain they experience rapid population decline due to changes in agriculture. The population dropped by about 60 percent in the past 40 years so it is possible that some of the rare dialects simply disappeared as a result of this population decline.”
Apart from bringing a fascinating story of lost bird’s dialects, Pavel Pipek says the research also has a number of practical implications for other fields of research, for instance invasion ecology:
“It is very important for my other field of interest which is invasion ecology. We are interested to know what is behind the successes of one type of invaders while others are failing. And the common sense explanation is the numbers of individuals which were imported, which definitely affects the outcome of any interaction.
Some of the things can be fairly theoretical such as we want to look if there are some barriers in the gene flow, in other words, whether the populations which are singing differently are mixing with each other. That might not be that important in our region, but it can have implications in conservation ecology.
“Another thing is that we revealed that if the population is decreasing, it affects the patterns of distribution of dialects. So you can also use the dialects for monitoring the state of the bird population. The songs can actually indicate that there is something going on the population level.”
“Nowadays, everyone can record high quality data using their smartphones. Citizen science is about mutual cooperation of scientists and volunteers. It should be enriching for both sides. For scientists it means that they can collect large and for the volunteers from the public it also has a number of benefits: they are in direct touch with science and acquire new knowledge and skills. So I hope that our project is a good example of citizen science.”