Wagtails are a group of passerine birds that form the genus Motacilla in the family Motacillidae. The common name and genus name are derived from their characteristic tail pumping behaviour. Together with the and they form the family Motacillidae. The forest wagtail belongs to the monotypic genus Dendronanthus which is closely related to Motacilla and sometimes included therein.
The willie wagtail ( Rhipidura leucophrys) of Australia is not a true wagtail; it was named as such by early settlers from England from its superficial similarity in colour and behaviour to the pied wagtail, but belongs to an unrelated genus of birds known as .
At first glance, the wagtails appear to be divided into a yellow-bellied group and a white-bellied one, or one where the upper head is black and another where it is usually grey, but may be olive, yellow, or other colours. However, these are not lineages; change of belly colour and increase of melanin have occurred independently several times in the wagtails, and the colour patterns which actually indicate relationships are more subtle.
mtDNA cytochrome b and NADH dehydrogenase Protein subunit 2 DNA sequence data (Voelker, 2002) is of limited use: the suspicion that there is a superspecies of probably three white-bellied, black-throated wagtails is confirmed. Also, there is another superspecies in sub-Saharan Africa, three white-throated species with a black breast-band. The remaining five species are highly variable morphologically and their relationships with each other and with the two have not yet been satisfactorily explained.
The origin of the genus appears to be in the general area of Eastern Siberia/Mongolia. Wagtails spread rapidly across Eurasia and dispersed to Africa in the Zanclean (Early Pliocene) The date of 4.5 mya in Voelker (2002) is dubious as it does not rely upon hard data but is merely an estimate based on average values now known to be often wrong. where the sub-Saharan lineage was later isolated. The African pied wagtail (and possibly the Mekong wagtail) diverged prior to the massive radiation of the white-bellied black-throated and most yellow-bellied forms, all of which took place during the late Piacenzian (early Late Pliocene), c. 3 mya.
Three species are poly- or paraphyletic in the present taxonomical arrangement, and either subspecies need to be reassigned and/or species split up. The western yellow wagtail (AKA blue-headed wagtail, yellow wagtail, and many other names) especially, has always been a taxonomical nightmare, with ten currently accepted subspecies and many more invalid ones. The two remaining "monochrome" species, Mekong wagtail and African pied wagtail may be closely related, or a most striking example of convergent evolution.
Prehistoric wagtails known from fossils are Motacilla humata and Motacilla major.
They are ground nesters, often in rock crevices on steep banks or walls, laying (3–)4–6(–8) speckled eggs at a time.Snow, D. W. & Perrins, C. M. (1998). The Birds of the Western Palearctic Concise Edition. OUP . Among their most conspicuous behaviours is a near constant tail wagging, a trait that has given the birds their common name. In spite of the ubiquity of the behaviour and observations of it, the reasons for it are poorly understood. It has been suggested that it may flush up prey, or that it may signal submissiveness to other wagtails. Recent studies have suggested instead that it is a signal of vigilanceRandler, C (2006). "Is tail wagging in white wagtails, Motacilla alba, an honest signal of vigilance?" Animal Behaviour 71 (5): 1089-1093 that may aid to deter potential predators.Hasson, O. (1991). "Pursuit-deterrent signals: communication between prey and predator". Trends in Ecology & Evolution, 6:325-329.
Temperate to subarctic Europe and western Asia; wintering in tropical Africa and southern Asia. |
Temperate to subarctic eastern Asia, also in Alaska in North America; wintering southern Asia and northern Australia. |
Temperate eastern Europe, western and central Asia; wintering southern Asia. |
Southern Africa from Uganda, the eastern DRCongo and Kenya, through Zambia and Angola to southern Africa, south to the Western Cape; non-migratory. |
Madagascar; endemic, non-migratory. |
São Tomé; endemic, non-migratory. |
Western Europe including the British Isles, southern Scandinavia, the Mediterranean region, and Macaronesia; also disjunct in temperate central and eastern Asia east to Kamchatka, and also the Himalaya to the Tien Shan. European populations largely resident or short-distance migrants; Asian populations migrate to southern Asia in winter. |
Guinea to Ethiopia south to South Africa. |
Breeds throughout Eurasia up to latitudes 75°N, only absent in the Arctic where the July isotherm is less than 4 °C. It also breeds in the mountains of Morocco and western Alaska. Short-distance migrant, wintering western and southern Europe south to north-central Africa and southern Asia. Occupies a wide range of habitats, but absent from deserts.Collins Bird Guide (page 250) by Mullarney, Svensson, Zetterstrom, & Grant |
Sub-Saharan Africa from the Eastern Cape north to extreme southern Egypt and from Guinea to western Eritrea and Somalia. |
Cambodia and Laos, largely resident, but a non-breeding visitor to nearby Thailand and Vietnam. |
Japan and Korea; non-migratory. |
India; non-migratory. |
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