Submission No 237: Black-headed Gull Larus ridibundus; Buffalo Creek, Darwin, NT. 1 February 1998 & 25 March 1998. Submitted by: Niven McCrie, Tom McCrie, J. Miles & D. Colbourne.

Verdict: Accepted

This record relates to the sighting of a gull observed at a high tide roost of gulls, terns and waders at Buffalo Creek, Darwin, NT. Several observations were made by a number of observers between 0730 and 1920 hrs. 1 February 1998. The bird was then briefly relocated 25 March 1998 at nearby location. A first class submission has been presented to the committee providing a comprehensive description and a full account of the circumstances behind the sighting. Complemented further by the inclusion of a photograph, details of notes taken in the field and a sketch. Explanations were also provided detailing why the observers consider this individual to be a Black-headed Gull in first-winter plumage.

The combination of the following main characters readily confirm the identification as a Black-headed Gull in first-winter plumage and safely eliminates all other possible contenders:

• Noticeably smaller size, slimmer build and more slender bill compared with Silver Gulls Larus novaehollandiae nearby.
• Pale-Grey upperparts of similar shade to or perhaps slightly darker than Silver Gull.
• Mostly white head marked with broken white eye-ring, dusky eye crescent and ear spot, plus two pale-grey bands running over top of head, one from eye to eye over the crown and another from ear spot to ear spot over the nape.
• White rump and tail with narrow dark subterminal band to latter.
• Pale-grey upperwing with prominent white wedge in outer-wing, narrow dark trailing edge, obvious dark markings on at least one tertial and an inner greater secondary-covert plus a few less obvious dusky markings apparently within the outer scapulars.
• Mostly grey underwing with narrow white slash along leading edge of outer-wing with contrasting blackish inner primaries.
• Slim, black-tipped orange yellow bill and dark pinkish or dull-red legs.

The apparent absence of a brown carpel-bar and the mostly pale-grey tertials and inner secondary-coverts (with only one obvious dark-centred feather remaining in each tract) suggests that the bird had begun the partial moult to first-summer plumage. The age and date of occurrence are in agreement with the now well-established pattern of vagrancy reported for the species in Indonesia, Papua New Guinea etc. Where, since the 1950’s, Black-headed Gulls have been increasingly reported during November-April, with the majority of records involving birds in first-winter plumage (Argeloo 1993).

The committee has no hesitation in unanimously accepting this record as a Black-headed Gull Larus ridibundus, representing the second confirmed record for Australia.

References and Bibliography

• Argeloo, M. 1993. Black-headed Gulls wintering in Sulawesi (and notes on their occurrence elsewhere in the Indo-Australia Region). Kukila 6 (2): 110-114.
• Grant, P.J. 1982. Gulls: A guide to identification. T. & A.D. Poyser. UK.
• Patterson, R.M. 1996. RAOU Records Appraisal Committee: Opinions and Case Summaries 1992-1995. Submission No.131. Black-headed Gull, Broome, WA, 19 October 1991. RAOU Report No. 101, May 1996.

Tony Palliser
Chairman Birds Australia Rarities Committee (BARC)