Yellow wagtail’s phylogeny is confusing : there are many subspecies, that are visually much different from each other. Some taxa like tschutschensis are now often considered as distinct species, and Citrine wagtail (Motacilla citreola) forms a cryptic species complex with flava (i.e there are hybrids).
Interestingly, the flight calls of these taxa are also different. Even if much caution must be taken regarding a sound-based subspecific identification, the following sonograms should help to point out some differences. Beware of song notes that can be very varied, but are longer and often doubled and are generally linked to specific behaviours. The following indications apply exclusively to typical flight calls. Also note that some of the Eastern/Mediterranean birds can produce flava-type calls.
In this article we’re going to discuss the flight call identification of :
- “Western yellow wagtail group” :
- Blue-headed wagtail (Motacilla flava flava)
- Yellow-crowned wagtail (Motacilla flava flavissima)
- Dark-headed wagtail (Motacilla flava thunbergi)
- “Eastern and Mediterranean yellow wagtail group” :
- Ashy-headed wagtail (Motacilla flava cinereocapilla)
- Iberian yellow wagtail (Motacilla flava iberiae)
- Black-headed wagtail (Motacilla flava feldegg)
- Eastern yellow wagtail (Motacilla tschutschensis)
- Citrine wagtail :
- Citrine wagtail (Motacilla citreola ssp citreola and werae)
1.Blue-headed wagtail (Motacilla flava flava) and the Western yellow wagtail group.
Flava is the nominate wagtail is Western Europe. Flavissima and Thunbergi sound very similar to flava so I’m not sure that there is much to say about a subspecific identification. Therefore, we will group them as the “western yellow wagtail type call “, which can be described as follows :
- First leg with two strongly ascending harmonics almost converging at the top of the note (about 8-8.5 kHz). The first harmonic is upcurved at the beginning. Louder part around 6-7 kHz
- The second is descending, louder and noisy, not much modulated, often with upcurved parts
- Length : about 0.25 seconds
- Frequency (approximately, at beginning and end of each leg) : 2.5 kHz -> 8kHz -> 4kHz
2.Ashy-headed wagtail (Motacilla flava cinereocapilla)
Cinereocapilla sounds more rasping than flava, with a highly modulated second leg.
- First leg with two strongly ascending harmonics ; the first one is upcurved, while the second one is downcurved, so that they look partly diverging or forming a diamond. The first harmonic has a well-defined angle separating its beginning from the start of the modulations. The beginning of the first harmonic is loud compared to flava type.
- The second is descending slowly and highly modulated. The modulation are high pitched (center around 6-7kHz with variations between 4 and 8kHz), and remain higher-pitched than flava until the end.
- Frequency (approximately, at beginning and end of each leg) : 2.5 kHz -> 8kHz -> 5-6kHz
Iberiae is supposed to sound like cinereocapilla, although I have the impression that it more often produces flava-type calls.
6.Black-headed wagtail (Motacilla flava feldegg)
Feldegg ‘s call is similar to Cinereocapilla‘s
- First leg with two strongly ascending harmonics ; the first one is gently upcurved and the second one is rather downcurved, thus creating a diamond shape
- The second leg is descending, downcurved and modulated. Yet, the modulation are not as broad as Cinereocapilla. The modulation are high pitched (center around 6-6.5kHz with variations between 5 and 8kHz) ang concentrated at or before a well-defined (sometimes almsot straight) angle. The note often goes lower than on Cinereocapilla. Typically, this second leg is thinner and more continuously modulated in Feldegg than in Cinereocapilla
- Frequency (approximately, at beginning and end of each leg) : 2.5 kHz -> 8kHz -> 3 kHz
7. Eastern yellow wagtail (Motacilla tschutschensis)
Tschutschensis‘s call is a rasping call, intermediate between flava and citreola
- First leg with two strongly ascending straight and parallel harmonics (much closer than on feldegg or cinereocapilla). They can reach pretty high frequences (>8kHz)
- The second leg is descending, slightly downcurved and highly modulated. The amplitude of the modulation decreases as the pitch decreases. the note remains high-pitched and doesn’t go below 5kHz, so that the second leg is much shorter (half ?) than the first leg (compare with citreola). Most of the modulations remain above 6kHz
- Frequency (approximately, at beginning and end of each leg) : 2.5 kHz -> 8kHz -> 5 kHz
8. Citrine wagtail (Motacilla citreola)
The Citrine wagtails has a very raspy call, with a quite typical n-shaped sonogram :
- Global “n” shape with the first leg as long as the second one or slightly longer
- First leg composed of two strongly ascending straight harmonics that are very close to each other and parallell (if the sound is too faint only one harmonic is visible.
- The second leg is descending,downcurved, louder and noisy, with the broader band at or before the angle
- Frequency (approximately, at beginning and end of each leg) : 2.5 kHz -> 6.5kHz -> 2.5kHz