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.
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.
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.
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.
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.
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.
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.