Citizen scientists help to map regional birdsong dialects across Europe
LINKED PAPER
Detailed large-scale mapping of geographic variation of Yellowhammer Emberiza citrinella song dialects in a citizen science project. Diblíková L., Pipek P., Petrusek A., Svoboda J., Bílková J., Vermouzek Z., Procházka P. & Petrusková T. 2018. IBIS. DOI: 10.1111/ibi.12621. VIEW
Since Aristotle, birdsong has fascinated us for millennia. Until the mid-20th century, however, many subtleties were unknown. Advances in technology has not only allowed more accurate recording and analysis of birdsong, but has also enabled scientists to involve the public, via citizen science projects, in the research of this fascinating phenomenon. This has proven to be especially beneficial for studying the geographical variation in birdsong.
It has been known for quite some time that some birds, mainly those that learn their vocalization, i.e. songbirds, hummingbirds and parrots, exhibit regional dialects. These have been most intensively studied on American Zonotrichia sparrows. The Palaearctic Yellowhammer Emberiza citrinella would seem to be an ideal species for such research: the males have very small repertoires, the song is simple and easy-to-remember and, especially in Central Europe, they are both common and familiar.
Variation in Yellowhammer song was already known by the 19th century, but even as recently as the 1980s, research was scattered and uncoordinated (reviewed in Petrusková et al. 2015). In 1985, the Danish ornithologist Paul Hansen established the now widely used nomenclature based on terminal syllables of the song (Fig. 1) that are shared by males within a dialect region. It is noteworthy that Hansen’ study involved volunteers recording songs, although in the pre-digital era it must have been a challenge.
Figure 1 Yellowhammer male perching on a twig. Sonograms of the two most common dialects in Europe are depicted in the bottom right corner © Petr Jan Juračka
Over 20 years later, in 2011, we engaged Czech citizen scientists, now equipped with digital cameras and cell phones, in mapping Yellowhammer dialects in Czechia, a country in the middle of Europe with an area of roughly 79,000 square kilometres (more details in the relevant BOU Blog post here). Originally, the project was only a part of one-year awareness campaign by the Czech Society for Ornithology to highlight the decline of birds across the agricultural landscape. The cooperation between scientists and volunteers was such a success that the project Dialects of Czech Yellowhammers continued even though the focus of the Czech Society for Ornithology moved to other “birds in need”. The project is still running, now reaching its eighth season, and developed from a conservation awareness campaign into a full scientific study.
Our paper recently published in IBIS (Diblíková et al. 2018) summarises the results from six years of the project. During that time, 160 volunteers, together with the project team, collected almost 4000 Yellowhammer songs from most of the Czech territory (Fig. 2). Along with seven previously described dialects distributed in mosaic-like fashion, four localities with unusual song variants (rare dialects) were identified. On the boundary between different dialects we occasionally found birds capable of singing both dialect variants. Although in general our results support Hansen’s dialect division, some of the previously recognized dialects seem to be part of a continuum, and cannot be clearly delineated. Some re-evaluation of Yellowhammer dialect nomenclature is thus warranted in the future.
Figure 2 Volunteers mapped much of the Czech territory. In total, seven previously described dialects were identified, along with four rare, and previously undescribed, dialects. Large regions dominated by one dialect within the country match well the dialect distribution across the national borders
The unprecedented coverage on both local and large scales makes this project a perfect springboard for further research on the development and maintenance of birdsong dialects. In comparison with past studies, we have an advantage that we can study the borders of the same dialect types at different places, and thus disentangle the local factors (e.g., habitat structure, population-specific song types) from the effect of dialects themselves. This will allow us, for example, to evaluate whether males or females respond to local familiar songs or to the dialect phrase itself. Furthermore, re-launching of such a citizen science project after a decade or more will allow testing the temporal stability of the dialect borders.
The project has also inspired similar projects on Yellowhammer dialects in other parts of the world, namely in the UK, Poland and Switzerland (Ambühl et al. 2017) and New Zealand (where it was introduced from the UK – see the relevant BOU Blog post here, Pipek et al. 2018). These are all hosted under one roof, on the yellowhammers.net website and @YDialects on Twitter. As the coverage of most of Europe still remains scarce, you are welcome to contribute Yellowhammer recordings from wherever you live or visit!
References
Ambühl P., van Boheemen S., Pipek P., Procházka P. & Ehrengruber M.U. 2017. Gesangsdialekte der Goldammer Emberiza citrinella in der Schweiz. Der Ornithologische Beobachter 114(1): 1–10.
Hansen, P. 1985. Geographic song variation in the Yellowhammer (Emberiza citrinella). Nat. Jutl. 21: 209–219.
Petrusková T., Diblíková L., Pipek P., Frauendorf E., Procházka P., Petrusek A. 2015. A review of the distribution of Yellowhammer (Emberiza citrinella) dialects in Europe reveals the lack of a clear macrogeographic pattern. J. Ornithol. 156: 263–273. VIEW
Pipek P., Petrusková T., Petrusek A., Diblíková L., Eaton M.A. & Pyšek P. 2018. Dialects of an invasive songbird are preserved in its invaded but not native source range. Ecography 41: 245–254. VIEW
Image credit
Featured image: Yellowhammer, Emberiza citrinella © Petr Jan Juračka
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