Abstract
BackgroundField studies from 2011 onwards have demonstrated the presence of a breeding population of Yellow Wagtails (Motacilla flava) in the Xinjiang Uygur Autonomous Region, China that is phenotypically distinct from known subspecies occurring in Asia. Here we describe the plumages and vocalisations of this population and discuss its taxonomic status.MethodsThe analysis of plumage is based on field studies and photos available online. Recordings of vocalisations are compared with recordings from other Yellow Wagtail populations, and differences are analysed based on sonograms. Mitochondrial DNA from one individual is compared to other Yellow Wagtail taxa.ResultsUnlike M. flava subspecies breeding in or near Xinjiang, males in the studied population show a blue-grey head without prominent white supercilium, being most similar to the widely disjunct M. f. cinereocapilla. They differ from the similarly widely allopatric M. f. thunbergi, which might occur as a migrant or vagrant in Xinjiang, by on average cleaner yellow breast and more extensive white on the throat, and from the widely disjunct M. f. plexa and M. f. macronyx, which might also occur on migration in that area, by softer contact calls and slower pace of song. Females are similar to female M. f. feldegg in plumage. The mitochondrial ND2 tree shows the single sample from Xinjiang to be nested in the clade of western Yellow Wagtail taxa.ConclusionWe discuss whether the Xinjiang breeding population could represent an intergrade between subspecies breeding nearby, or whether it is better regarded as a separate as yet unrecognized subspecies. We argue that the localization of its apparent range in relation to other subspecies along with fairly consistent male and female plumages suggest that it is more likely to represent an undescribed taxon, but conclude that more research is needed to firmly establish its status.
Highlights
Field studies from 2011 onwards have demonstrated the presence of a breeding population of Yellow Wagtails (Motacilla flava) in the Xinjiang Uygur Autonomous Region, China that is phenotypically distinct from known subspecies occurring in Asia
Based on the discordance between mitochondrial and nuclear genetic data identified by Alström and Ödeen (2002), Drovetski et al (2018) and Harris et al (2018), and the overall slight nuclear genetic divergence, we chose in this paper to tentatively not adopt the split into two separate species but instead treat all discussed forms as Yellow Wagtail Motacilla flava
Distribution Based on our field studies and the reviewed online photos, we assert that the Xinjiang population of greyheaded Yellow Wagtails are summer visitors primarily to the belt of cultivated land running from the Urumqi area westwards along the northern slopes of the Tien Shan range and in cultivated areas around Jiyekexiang and Tarbagatay
Summary
Field studies from 2011 onwards have demonstrated the presence of a breeding population of Yellow Wagtails (Motacilla flava) in the Xinjiang Uygur Autonomous Region, China that is phenotypically distinct from known subspecies occurring in Asia. Based on the discordance between mitochondrial and nuclear genetic data identified by Alström and Ödeen (2002), Drovetski et al (2018) and Harris et al (2018), and the overall slight nuclear genetic divergence, we chose in this paper to tentatively not adopt the split into two separate species but instead treat all discussed forms as Yellow Wagtail Motacilla flava. Tschutschensis by Alström and Mild 2003 but better regarded as a separate subspecies or an intergrade, see Hellquist 2021) were found breeding in the Altai Mountains in the northeastern part of the region. Macronyx (hereafter thunbergi, cinereocapilla, pygmaea and macronyx, respectively) were observed. At three sites, they appeared to be territorial (Fig. 1):
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