With many Siberian Accentors (Prunella montanella) arriving in Europe and the possibility to discover these birds in central Europe, we were interested in whether it is possible to distinguish the two species, Siberian Accentor and Dunnock (Prunella modularis), by their calls. This is of special interest as it is often hard to get views of accentors – identification by call would help a lot to discover them.
We don’t have any experience with Siberian Accentor in the field. We just listened to the available recordings of Siberian Accentor (n = 14). As these recordings contained almost only one type of call (the high ringing one, often uttered in flight by accentors) we confine this article to this type of call.
Dunnocks have some other calls, the high ringing call is actually the only one we ever heard of flying birds, but it is also often used by perched birds. This is why Glutz von Blotzheim & Bauer (2001) for example call it contact call. But as there are other calls that could be named contact calls as well, we prefer to name it flight call here.
For comparison, we checked as many recordings of Dunnock as possible (47 recordings from Xeno-Canto contained flight calls, 34 recordings from waarneming.nl and waarneming.be contained flight calls, 17 recordings of flight calls of Julien Rochefort, 56 recordings of the flight calls from Ralph as well as the recording available on Chappuis (1987). Peter Schleef sent sonograms of flight calls of about 150 different birds and also checked many of his own recordings of the flight calls of accentors (no number available).
Additionally about 300 recordings of Dunnock were checked for similar calls (from all these sources).
Calls of Dunnock
The flight calls of Dunnock are quickly repeated elements, each of them consists of a lower pitched falling line and a higher pitched, even steeper, (most times) shorter line uttered at the same time by the other part of the syrinx. In some cases, this higher pitched line is missing (see sonogram 1, call 9 & 10), then the calls sound much clearer.
The variation of the flight calls is not very large – however especially in the early migration season, it is higher. We think that it is due to the younger age of the first year Dunnocks (maybe first year Dunnocks additionally migrate earlier?). As shown in other passerine species (cf. with Constantine & The Sound Approach (2006) for example), these calls are probably still more variable.
Especially the first or first few elements are affected. In some calls the first element can look quite strange (for example sonogram 1, 7 & 12), in other calls there is a connection between the first two elements, resulting in a zig-zag line (see sonogram 1, 15, 16 & 17).
There is one recording which does not fit well into this variation – we will talk about it in the end.
Sonogram 1: Flight calls of different Dunnocks (P. modularis). 1. 24.09.2015, Freiburg, Germany (further Dunnocks, Blackbird and Carrion Crow in background) © Ralph Martin; 2. 15.10.2016, Freiburg, Germany (Blackbird, Great Tit, Goldcrest, Chiffchaff, Greenfinch, Brambling in the background) © Ralph Martin; 3. 24.09.2015, Freiburg, Germany (further Dunnocks, Carrion Crow, Robin, Song Trush, Chaffinch in background) © Ralph Martin; 4. 26.10.2016, Freiburg, Germany (Great Spotted Woodpecker, Robin, Fieldfare, Chaffinch in background) © Ralph Martin; 5. 05.09.2013, Essonne, France (Great Spotted Woodpecker, Chiffchaff calls and song, Carrion Crow in background) © Julien Rochefort; 6. 20.10.2016, Freiburg, Germany (Robin, Song Trush, Blackbird, Chiffchaff, Greenfinch in background) © Ralph Martin; 7. 26.10.2016, Freiburg, Germany © Ralph Martin; 8. 24.09.2015, Freiburg, Germany (Great Tit, Carrion Crow, Meadow Pipit in background) © Ralph Martin; 9. 27.09.2015, Freiburg, Germany (Chaffinch, White Wagtail, Great Tit, Blackbird in background) © Ralph Martin; 10. 20.09.2015, Terschelling, Netherlands © Joost van Bruggen; 11. 25.09.2006, Ile-de-France, France (Great Tit, Robin, Blackbird, Chaffinch in background) © Julien Rochefort; 12. 28.09.2013, Straumsbukta, Norway © Stein Ø. Nilsen; 13. 02.11.2004, Ile-de-France, France (Carrion Crow in background) © Julien Rochefort; 14. 26.10.2016, Freiburg, Germany (Fieldfare, Robin, Meadow Pipit, Chaffinch, Goldfinch in background) © Ralph Martin; 15. 05.09.2006, France (Great Spotted Woodpecker, Robin, Great Tit, Chiffchaff, Magpie, Chaffinch in background) © Julien Rochefort; 16. 12.09.2016, France (Tree pipit, Chiffchaff, Robin, Wren, Carrion Crow in background) © Julien Rochefort; 17. 09.09.2009, France (Tree Pipit, Great Tit in background) © Julien Rochefort; 18. 08.10.2007, Ile-de-France, France (Goldcrest, Chaffinch in background) © Julien Rochefort
Calls of Siberian Accentor
Listening to calls of Siberian Accentor, they sound very clear and a little bit higher pitched than Dunnock’s calls. Looking at the sonogram, we can see why the call sounds so clearly: the second, higher pitched part uttered by the other side of the syrinx that we know from Dunnock, is usually missing (or less obvious). But be careful, this can be also done by Dunnock (and rarely Siberian Accentor can have this second element more obvious, too (see sonogram 2, 11)).
It is hard or impossible to identify the calls by ear in the field, but it should be possible to get alerted that there might be a Siberian Accentor in front of you.
Looking at the sonogram in more detail, there is another difference: The single elements of the call are not a falling line like in Dunnock – every element is actually „V“-shaped with a very prominent rising second half of each element. The pitch of the second half can reach even higher in frequency than the first half.
Sonogram 2: Flight calls of different Siberian Accentors (P. montanella). 1. October 2002, Hebei, China © Jännes (2003); 2. 16.10.2016, Hanko, Finnland (Fieldfare, Great Tit in background) © A. Forsten; 3. 27.1.2016, Japan (White Wagtail, Redpoll and other birds in background) © Susumu Sato; 4. 01.12.2013, Andong, South Korea (Magpie and probably Rustic Bunting in background) © 하정문; 5. 07.11.2012, Dalian, Lianoning, China (Wren, Rustic Bunting in background) © Dong Bei; 6. 24.11.2012, West Daejeon, South Korea © Grant Fisher; 7. 27.08.2016, Zeysky District, Amur Oblast, Russia (Goldcrest, Coal Tit, Willow Tit in background) © Alex Yakovlev; 8. 23.10.2016, Kläranlage Ladebow, Germany (Tundra Bean Goose, Bearded Reedling, Reed Bunting in background) © Marcel Tenhaeff; 9. 11.02.2012, Laotieshan, Liaoning, China © Tom Beeke; 10. 26.10.2016, Czarnowo Wielkie, Poland (Great Tit, Yellowhammer, Linnet in background) © Dawid Czqstkiewicz; 11. another call of the same bird as 7.; 12. 20.10.2016, Greifswalder Oie, Germany (Dunnock is uttering the other call type in the recording) © Jonas Buddemeier
We found another call of Siberian Accentor in about half of the recordings, being even more specific. It seems to be uttered in similar circumstances and sounds very similar to the flight calls. These other calls seem to be a little bit lower pitched than the other flight calls of Siberian Accentor. We named them call type 2 here.
In the sonogram we can see that the last elements of the row consist of rising lines only (so no ‚V‘-shape). We don’t know exactly the corresponding call of Dunnock (maybe it is just too similar to the typical flight calls to recognize). Also in Siberian Accentor the differences between these two calls do not always seem to be that clear. However we couldn’t find a comparable call of Dunnock with just rising elements.
Sonogram 3: Flight call type 2 of different Siberian Accentors (P. montanella). 1. 16.10.2016, Hanko, Finnland (Fieldfare, Great Tit in background) © A. Forsten; 2. 13.10.2016, Poland (Great Tit, Chaffinch in background) © Marcin Solowij; 3. 21.04.2016, Muraviovka Park, Amur Oblast, Russia © Tom Wulf; 4. 23.10.2016, Kläranlage Ladebow, Germany (Tundra Bean Goose, Bearded Reedling, Reed Bunting in background) © Marcel Tenhaeff
We didn’t notice a difference between the two subspecies of Siberian Accentor, P. m. montanella (breeds extreme NE Europe and W Siberia) and P. m. badia (breeds NE Siberia), mentioned by Hatchwell (2016). However there is not enough material for such a comparison. We also noticed no obvious geographical variation in the Dunnock calls.
As mentioned above, there seems to be an audible difference in pitch, so we measured the frequency of the calls. For comparison, we measured the average frequency (mean of highest and lowest frequency) of the lower line of the first element of the call. For each bird, we measured three calls and averaged these measurements in table 1.
Diagram 1: Same data as in table 1 as a boxplot. The thick vertical line in the box is the median, between the upper limit of the box and the lower limit of the box are 50 % of the data, between the upper and lower whiskers are (almost) 100 % of the data. The little rings show outliers.
Measurements overlap but there is an obvious difference.
Everything seems to be clear now? No, not completely. There is one strange recording, uploaded as Dunnock, that we have already mentioned: It was taken in Cheboksary, Russia on 08.09.2013 by Albert Lastukhin (see sonogram 4). In the beginning, a typical Dunnock is calling. At 26 seconds, there is a cut and there are suddenly other background noises and an accentor calls that is much more interesting. The shape of the elements seems to be closer to Siberian Accentor, the upper lines uttered by the other syrinx are recognizable but not very pronounced and the pitch is quite high. The breeding grounds of Siberian Accentor lie about 1000 km further north, however Glutz von Blotzheim & Bauer (2001) mention that migration already starts in the end of August in the Ural mountains. It is not completely unlikely that this is a migrating Siberian Accentor. So what is this bird? We are not sure. The call is somewhat intermediate in all features. Maybe it is possible to identify this call sometimes in future when more reference material will be available.
Sonogram 4: Recording of Dunnock, the discussed recording and two recordings of Siberian Accentor. 1. 05.09.2013, Essonne, France © Julien Rochefort; 2. 18. 08.09.2013, Cheboksarskiy rayon, Russia (in the first 26 seconds Dunnock, Chaffinch, Tree Pipit, Meadow Pipit, Goldfinch, Yellowhammer, then the mentioned Accentor, White Wagtail, Skylark, Bee-eater, Yellowhammer, Linnet, Tree Pipit, Chaffinch in background) © Albert Lastukhin; 3. & 4. 27.08.2016, Zeysky District, Amur Oblast, Russia © Alex Yakovlev
Looking at the results of this analysis, we suggest that birds which show an obvious ‚V‘-shape of all elements of the calls and with at least few calls higher than 6 kHz (measured as explained left of table 1) are actually identifiable as Siberian Accentor. Also birds uttering the call type 2 (sonogram 3) are identifiable as Siberian Accentor.
But what about the other accentor species – Alpine Accentor, Radde’s Accentor and Black-throated Accentor? Alpine Accentor has no call that could be confused with Siberian Accentor flight calls. Since Ralph’s last encounter with Radde’s Accentor, many years have gone. He didn’t hear flight calls back then and there is no recording of the calls available. Ralph watched many Black-throated Accentors in the Tienshan mountains during three trips, however the „flight calls“ are rarely heard during the breeding season. There is just one recording available of the calls in a migratory/nonbreeding context. In some of Ralph’s recordings of singing birds from Kyrgyzstan, the birds uttered calls sounding like the flight calls just before the song. We have comparable examples of Dunnocks, uttering „flight calls“ just before the song but these calls are sometimes similar to the flight calls, sometimes not. Therefore it is impossible to use these recordings for comparison.
With just one recording left, it is hardly possible to discuss the identification. However, there are obvious differences: the elements are not „U“-shaped as in Siberian Accentor, there is no second element uttered by the other side of the syrinx as in Dunnock and the call seems to be pitched quite highly (5.8 kHz). If the features shown by this recording are consistent within Black-throated Accentor, a seperation between Black-throated Accentor and Siberian Accentor is unproblematic. Seperation of Dunnock and Black-throated Accentor should be more problematic.
We have to thank Thijs Fijen, Lukas Pelikan, Julien Rochefort & Peter Schleef, for their comments and their recordings, Mika Bruun and Steve Klasan for their great photos and all the recordists for sharing their precious recordings.
Chappuis, Claude. 1987. Migrateurs et Hivernants.
Constantine, M. & The Sound Approach. 2006. “The Sound Approach to Birding.” The Sound Approach
Glutz von Blotzheim, Urs N., and Kurt M. Bauer. 2001. Handbuch Der Vögel Mitteleuropas Band 10/II.
Hatchwell, B. 2016. “Siberian Accentor (Prunella Montanella).” In Del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (Eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (Retrieved from http://www.hbw.com/node/58216 on 13 November 2016).
Jännes, Hannu. 2003. Calls of Eastern Vagrants. Earlybird.