Eastern Yellow Wagtails

Continuing from my previous post about juvenile Eastern Yellow Wagtails (Motacilla tschutschensis), in this post, I’ll share some of my images and notes about the adult in breeding plumage. Over the last spring, I was able to observe many adults that were passing through Mae Faek paddies. They normally gathered in big flocks at dusk and roosted together in the dry grassy patch where many pipits and larks were also found to use as roosting site. These wagtails proved to be much more difficult to approach than the pipits and larks. They were very wary and difficult to get close even with a car, so I had to put even more effort than usual to get some decent shots of them.

Male tschutschensis (12 April 2021)

I recorded Eastern Yellow Wagtails coming to roost at Mae Faek between 12 April to 3 May 2021. The numbers ranged between just few individuals up to approximately 50 birds, peaking around late April. It was really interesting, and highly confusing, to see a wide range of plumage variation among these birds. Let’s see some of these plumage types, which I’ll try to identify to the subspecies level.

Male tschutschensis; note the long bold white supercilium (23 April 2021)
Male tschutschensis (23 April 2021)
Male tschutschensis (19 April 2021)
Female tschutschensis; note the overall duller plumage (19 April 2021)
Female tschutschensis (23 April 2021)

Let’s start with the nominate race, M. t. tschutschensis. It was probably the most abundant taxon that I observed at Mae Faek paddies. In the breeding plumage, it can be told by the long bold white supercilium. The male has bluish-grey head with slightly darker ear-coverts. The female is similar to the male, but with overall duller plumage and paler grey head. There seems to be a variation of breast marking in all subspecies. Some birds had clean yellow breast and underparts, while some had olive wash or spots either restricted to the breast sides or across the breast.

Male plexa; note the faint supercilium and dark ear-coverts (12 April 2021)
Male plexa (22 April 2021)
Male plexa (15 April 2021)
Male plexa (20 April 2021)
Female plexa (24 April 2021)

Next taxon, M. t. plexa, is another member of the tschutschensis subspecies group. It differs from the nominate by having much thinner and fainter white supercilium. The ear-coverts are also slightly darker. The female of this taxon seems to be slightly darker than the male with duller grey crown and a mix of olive and dark grey ear-coverts. There were fewer of this taxon compared to the nominate, but they were not uncommon.

Male similima; note overall bright plumage and short supercilium (15 April 2021)

The third member of the tschutschensis subspecies group is the race M. t. similima. This taxon was not common at Mae Faek. I only managed to photograph just one bird on 15 April 2021. There were probably just 1-2 more birds throughout the whole season. It can be told from other similar subspecies by the overall brighter plumage. The head appears to be brighter bluish-grey and the upperparts are also brighter yellowish-olive than in other subspecies. The white supercilium is bold and distinct but rather short. It also seems to have a more pronounced white lower eye-ring than in other subspecies.

Male angarensis; note dark slate-grey crown, loral stripe and ear-coverts (15 April 2021)
Male angarensis (15 April 2021)
Male angarensis (15 April 2021)

The last member of the tschutschensis subspecies group that can be found in Thailand is the race M. t. angarensis. It seemed to be the least common taxon at Mae Faek. I only found and photographed just one bird on 15 April 2021. Compared to other similar subspecies, it has distinctly darker slate-grey crown, loral stripe and ear-coverts. The individual that I found also had a very pronounced white lower eye-ring. I assume that it’s also the least common taxon of this subspecies group in Thailand too, as I have never seen it anywhere before.

Male macronyx; note the lack of white supercilium (24 April 2021)
Male macronyx (24 April 2021)
Male macronyx; this individual had completely yellow underparts reaching up to the chin (14 April 2021)
Another photo of the same bird (14 April 2021)
Male macronyx; some birds appeared to have darker ear-coverts (23 April 2021)
I believe this is also a male macronyx even though it had a slight hint of white on the supercilium (15 April 2021).
Female macronyx (17 April 2021)

The last taxon that I found at Mae Faek, and was able to identify, was the race M. t. macronyx or the “Manchurian Yellow Wagtail”. The male of this subspecies can be easily told from other subspecies by completely lacking the white supercilium. The female is paler and duller, often with a slight hint of white above and below the eye. I also noticed a variation in the extent of yellow on the underparts and darkness of the ear-coverts. Most birds would have white chin, but some appeared to have extensive yellow on the underparts reaching up to the chin. The ear-coverts can also be very dark in some birds as well. This taxon was more or less equally abundant as the nominate at Mae Faek during the spring passage.

It’s really interesting, and quite disappointing, that not a single taivana (or the “Green-headed Wagtail”) was seen throughout the entire spring. Not sure if they migrated back much earlier than other subspecies, or they just use a completely different route or roosting habitat in spring. Anyway, there were some other birds that I wasn’t sure about the identification of the subspecies. Here are some of the confusing ones.

This male had an unusually distinct olive marking on the breast, looking almost like a breast band. It also had some white around the supercilium and very dark ear-coverts. I guess plexa would be the closest option, but I’m not sure if they can have such little white on the supercilium (19 April 2021).
Another photo of the same bird showing the unusually distinct breast band (19 April 2021)
Back side of the same bird; note the very dark ear-coverts (19 April 2021)
Another bird, also a male, with similarly faint white supercilium and dark ear-coverts. I guess this is one end of the variation range for plexa (22 April 2021).
This individual has an interesting amount of olive on the crown. Judging from the brightness of the plumage, it seems to be a male, most likely the subspecies macronyx. I don’t think I’ve ever seen a male in breeding plumage with such amount of olive going up to the crown area. It doesn’t seem to be a young (first-summer) bird either. Not sure what’s going on here. (20 April 2021)
The same bird from a different angle. It even showed a hint of yellow around the base of supercilium. Along with the olive patches on the crown, this might suggest hybridisation between macronyx and taivana? Both races seem to have an overlap in the breeding area around Amurland. (20 April 2021)

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