Submission No 200: Black-backed Wagtail Motacilla lugens, Derby, WA. 30 December 1995 to 6 January 1996. Submitted by: J. Fallaw & B. Hayward.

Verdict: Accepted

An observation of a bird at Derby Wharf, WA, originally reported by Sister Pat Comeford and later Pam Masters. Two birds were found on 30 December 1995 but subsequently only one individual was seen. This bird remaining until 6 January 1996 and was sighted by a number of observers including J.Fallaw, B Hayward and G Swan. Field notes and photographs were provided to the committee as part of the submission.

Many of the key characters were noted in the description including: A white forehead, black line extending from the base of the bill through the eye to the nape, black crown extending on to the mantle, grey back with definite black patches, black rump & uppertail, white chin & throat, large black bib on the breast, white belly, grey edged tertials, black scapulars mottled with grey, white median coverts, and greater coverts grey, tinged with black. One observer described the open wings as ‘white with the tips of the primaries dark grey/black’. Much of this detail was confirmed by the photographs.

The black line through the eye instantly narrows the option to either M lugens or M alba ocularis. Committee members felt that of the two, identification as lugens was indicated by the the extensive amount of white reported on the remiges, the black rump & uppertail combined with the black markings present on the mantle. One committee member had some reservation as to whether the extent of white in the open wing was really present but went on to point out that the black on the back is more indicative of lugens than ocularis. Adding that, Howell (1990) indicates that adult male ocularis may also have black in these areas but to a lesser degree. Other characters such as the white bases to some tail feathers and the dimensions of the bill could not be ascertained.

Following two rounds of voting and much research into the identification of M. lugens and M. alba ocularis the committee resolved to accept this as a record of Black-backed Wagtail Motacilla lugens. This is only the second to be accepted by the committee.

References and Bibliography

• Christidis, L & Boles, W.E. (1994). The Taxonomy and Species of Birds of Australia and its Territories. R.A.O.U. Monograph 2. RAOU, Hawthorn East, Melbourne.
• Howell, S.N.G. (1990). Identification of White & Black-backed Wagtails in Alternate Plumage. Western Birds 21: 41-49.
• Morlan, J. (1981). Status & Identification of forms of the White Wagtail in Western North America. Continental Birdlife 2: 37-50.
• Roberson, D. (1982). Black-backed Wagtail Motacilla lugens / White Wagtail M alba. Birding 15: 127-129.
• Sharpe R.B. (1885). Catalogue of the Passeriformes in the collection of British Musuem, Vol 10: 482-6, British Museum, London.
• Sibley, C.G. & Monroe, B.L., Jr. 1990. Distribution and Taxonomy of Birds of the World. Yale University Press, New Haven.

Tony Palliser
Chairman Birds Australia Rarities Committee (BARC)