Reference species – published on 4th of January 2018
See Motacillidae family (pipits, wagtails, longclaws…)
In French: Bergeronnette des ruisseaux en français
Grey Wagtail is one of the most widespread passerine in the Old World. It is seen in virtually all Eurasia, and also in Africa. It is common and doing well, as it is well adapted to man-made habitats. Its identification is easy and well covered in most bird books. Here, we will rather use the beautiful wagtail to explain some generalities that are not always well described to birdwatchers.
Illustration of “Bird-in-tuition” method
Our species, with its very long tail, reduced or invisible wing bars, as well as upper- and under-tail coverts yellow doesn’t have any identification issue. Other “yellow” wagtails have wing bars and much shorter tail.
Our reference here is rather the “group of family” as described in the Bird-in-tuition method: the “insectivorous passerines”. They show long and thin bill, deep belly and typical behaviour. It is also showing the family Motacillidae (pipits, wagtails and longclaws) features, notable the very long tertials covering entirely or almost entirely the primaries (no or virtually no primary projection).
Juvenile passerines are often identified with bare gape and fresh and very clean regular greater coverts tipped whitish. They are usually duller than adults and their tail, sometimes also their bill, are shorter. In several wagtails (Motacilla), some pipits (Anthus) and longlaws (Macronyx), juveniles show a “collar” on breast not shown by adults.
Taxonomy and sub-species
Grey Wagtail is an example of “cline”. In its wide geographical range, there is visible differences between the extremes, but no clear-cut limit between them, Western birds tending to be paler and longer-tailed, and Eastern bird being slightly darker and short tailed. Up to 7 sub-species were described, but IOC lists only 3 of them while this might change in the future.
Only two isolated population in the Atlantic are seen as separate subspecies: Motacilla cinerea patriciae in the Azores and Motacilla cinerea schmitzii in Madeira. All other birds from Canary Islands to Eastern Russia are seen as nominal Motacilla cinerea cinerea.
Grey Wagtail is a well distinct species genetically and no sister-species are known. It superficially looks like Mountain Wagtail (Motacilla clara) of sub-Saharan Africa, but they have been found not so closely related, thus similar shape and behaviour is seemingly due to convergent evolution and not from recent common ancestor as previously believed by ornithologists.
[Species #4 of the Holistic Encyclopedia of Birds project]
All photos and text are © Valéry Schollaert and Marinella Mejia