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Case Summary for:
Submission No 215: White Wagtail Motacilla alba, Darwin, NT, June 1996. Submitted by Niven McCrie. Verdict: Accepted This record relates to a number of sightings of a bird presumed to be the same individual at Darwin Sewage Works over a four year period, each dry season from April / May 1993 to at least June 1996. Observations were made by many ornithologists over this period with photographs and field notes provided as part of an excellent submission to the committee. The description and photographs supplied provide detail that positively identifies the bird photographed in June 1996 as Motacilla alba leucopsis. Particularly striking and convincing was the white face, throat, chin and forehead combined with the lack of a dark eye-stripe. The lack of an eye-stripe safely eliminates Black-backed Wagtail Motacilla lugens and other races of Motacilla alba. The rather dark-grey saddle seemingly indicating that this bird was a male. Determining the exact age however is difficult, the dark grey saddle (mantle, back and scapulars) combined with in-coming black feathers suggest a pre-alternate moult and taking into account the dark feathering on the worn secondary coverts (depicted in the photographs and notes provided) suggest a first year bird moulting to first alternate plumage (Sharpe 1885). Bearing in mind that once an adult male leucopsis acquires a fully black saddle it will be retained thereafter in both basic and alternate plumages (Sharpe 1885) the logical conclusion therefore being that the 1996 bird was probably a first year male, whereas the bird with a fully black saddle seen in previous years must have been one or more different individuals. The committee has no hesitation in unanimously accepting this record as a White Wagtail Motacilla alba leucopsis.
References and Bibliography
Tony Palliser |