Wagtail
214424
217246117
2008-06-05T05:33:59Z
86.140.60.92
/* Systematics */ typo
{{Taxobox
| name = Wagtails
| image = Africanpiedwagtail45.jpg
| image_caption = African Pied Wagtail
| regnum = [[Animal]]ia
| phylum = [[Chordate|Chordata]]
| classis = [[Bird|Aves]]
| ordo = [[perching bird|Passeriformes]]
| familia = [[Motacillidae]]
| genus = '''''Motacilla'''''
| genus_author = [[Carolus Linnaeus|Linnaeus]], 1758
| subdivision_ranks = Species
| subdivision =
Many, see text.
}}
The '''wagtails''' form the [[passerine]] [[bird]] genus ''Motacilla''. They are small birds with long tails which they wag frequently. '''''Motacilla''''', the root of the [[family]] and [[genus]] name, means ''moving tail''. The [[Forest Wagtail]] belongs to the [[monotypic]] genus ''Dendronanthus'' which is closely related to ''Motacilla'' and sometimes included herein.
The [[Willie Wagtail]] (''Rhipidura leucophrys'') of [[Australia]] is an unrelated bird similar in colouration and shape to the [[Japanese Wagtail]]. It belongs to the [[fantail|fantail flycatcher]]s.
==Characteristics==
Wagtails are slender, often colourful, ground-feeding [[insectivore]]s of open country in the [[Old World]]. They are ground nesters, laying up to six speckled [[Egg (biology)|egg]]s at a time.{{Fact|date=February 2008}} 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 vigilance to potential predators.<ref>Randler, C (2006). "Is tail wagging in white wagtails, ''Motacilla alba'', an honest signal of vigilance?" ''Animal Behaviour'' '''71''' (5): 1089-1093 [http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6W9W-4JVTCJT-3&_user=1495406&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000053190&_version=1&_urlVersion=0&_userid=1495406&md5=10c93957b3f88d2728130514cdab471d Abstract]</ref>
==Systematics==
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 gray, but may be olive, yellow, or other colors. However, these are not [[evolution]]ary lineages; change of belly color and increase of [[melanin]] have occurred independently several times in the wagtails, and the color patterns which actually indicate relationships are more subtle.
[[mtDNA]] [[cytochrome b|cytochrome ''b'']] and [[NADH dehydrogenase]] [[subunit]] 2 [[DNA sequence|sequence]] data (Voelker, 2002) is of limited use: the suspicion that there is a [[superspecies]] of probably 3 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 among each other and to the two [[clade]]s is not explained to satisfaction as of now.
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]])<ref>
The date of 4.5 [[mya (unit)|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.</ref>
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), approximately around 3 mya.
Three species are poly- or paraphyletic in the present [[taxonomy|taxonomical]] arrangement and either [[subspecies]] need to be reassigned and/or species split up. The [[Blue-headed Wagtail]] (AKA Yellow Wagtail and many other names), especially, has always been a taxonomical nightmare with over a dozen currently accepted subspecies and many more invalid ones. The two remaining "[[monochrome]]" species, [[Mekong Wagtail|Mekong]] 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''.
See the species accounts for more on individual species' relationships.
==Species in taxonomic order==
*[[White Wagtail]] ''Motacilla alba'' - [[polyphyletic]] or [[paraphyletic]]
**Pied Wagtail ''Motacilla alba yarrellii''
**[[Black-backed Wagtail]] ''Motacilla (alba) lugens''
*[[Japanese Wagtail]] ''Motacilla grandis''
*[[White-browed Wagtail]] ''Motacilla madaraspatensis''
*[[Mekong Wagtail]] ''Motacilla samveasnae''
*[[African Pied Wagtail]] ''Motacilla aguimp''
*[[Citrine Wagtail]] ''Motacilla citreola'' - possibly [[paraphyletic]]
*[[Yellow Wagtail]] ''Motacilla flava''
**Yellow Wagtail ''Motacilla flava flava'' - [[paraphyletic]]
*[[Grey Wagtail]] ''Motacilla cinerea''
*[[Cape Wagtail]] ''Motacilla capensis''
*[[Madagascar Wagtail]] ''Motacilla flaviventris''
*[[Mountain Wagtail]] ''Motacilla clara''
The Mekong Wagtail was described as new to science only in [[2001]].<!-- Duckworth et al. -->
==External links==
*[http://ibc.hbw.com/ibc/phtml/familia.phtml?idFamilia=123 Wagtail videos] on the Internet Bird Collection
==References==
* '''Voelker''', Gary (2002): Systematics and historical biogeography of wagtails: Dispersal versus vicariance revisited. ''[[Condor (journal)|Condor]]'' '''104'''(4): 725–739. [English with Spanish abstract] [[Digital Object Identifier|DOI]]: 10.1650/0010-5422(2002)104[0725:SAHBOW]2.0.CO;2 [http://www.bioone.org/perlserv/?request=get-abstract&doi=10.1650%2F0010-5422(2002)104%5B0725%3ASAHBOW%5D2.0.CO%3B2 HTML abstract]
===Footnotes===
<references/>
[[Category:Motacilla|*]]
[[Category:Genera of birds]]
[[eo:Motaciloj]]
[[fa:دم جنبانک]]
[[fr:Motacilla]]
[[it:Motacilla]]
[[he:נחליאלי]]
[[sw:Tikisa]]
[[lt:Kielės]]
[[pt:Alvéola]]
[[ru:Трясогузки]]
[[sv:Ärlesläktet]]
[[th:นกกระเด้าลม]]
[[tr:Kuyruksallayan]]
[[zh:鶺鴒屬]]