birding-aus

Lesser Black-backed Gull in Broome

To: <>, "Nikolas Haass" <>
Subject: Lesser Black-backed Gull in Broome
From: "Mike Carter" <>
Date: Mon, 21 Jan 2013 14:13:27 +1100
We (Rohan Clarke, Richard Baxter, Frank O'Connor and I) are back from Broome where the Lesser Black-backed Gull was easily found and viewed. Before we got there George & Jim had taken more photos from better angles, fuller profile shots, which confirmed our judgements from the earlier images. While we were there ca. 1,000 photos were taken notably by Rohan Clarke, photographer extraordinaire, and nine of those are already in circulation and will no doubt, soon be posted on his web site http://www.pbase.com/wildlifeimages but I did not find them when I looked this morning. Virtually all aspects are depicted. Firstly for those interested in twitching this bird, the rubbish tip is in the ominously named Buckley's Street (or Road), a ten minute drive from China Town, Broome. Probably because we there on a Saturday morning when no heavy vehicles were operating, there was no hesitation from gate control in allowing us in. Note that we arrived at different times in 4WD vehicles and were allowed to drive anywhere but wandering about on foot was not permitted. Entry on week days and after rain may be more difficult and due to the undulating nature of the site, the bird is unlikely to be easily visible from outside the fence. The site was muddy with pools of water and torrential rain that afternoon after we had left may have made it impassable. The bird was present throughout our stay, often associating with Silver Gulls. As previously stated, anyone experiencing difficulty should contact George Swann. And don't forget that the Semi-palmated Plover should still be around Broome. Whilst this bird could easily be mistaken for a Kelp Gull, there are several characters, some more subjective than others, that proclaim that this is not a Kelp Gull. These include structural features such as general shape being more gracile, smaller head, slighter bill as well as plumage features such as more greyish tones to upperparts. The most convincing, measurable features are the obviously longer wings projecting much further beyond the tail and the moult stage. The bird is one of two similar taxa, which according to the latest IOC classification as adopted by BARC, are both subspecies of Lesser Black-backed Gull Larus fuscus. These are the nominate fuscus (Baltic Gull) favoured by some, me included although I oscillate, and the race heuglini (AKA Heuglin's Gull) favoured by others. Most consider it too dark for the race taimyrensis. Expressing the moult situation in the manner set out by Nikolas in the email below obscures important details. There are clearly two feather generations in the primaries. Whilst slightly worn indicating that they are not fresh feathers, p1 to p6 are much newer than p7 to p10, which are very old and worn. Whilst this moult pattern does fit heuglini, it also fits fuscus so is of little or no value in determining subspecies. Using the wing tip diagrams in the Olsen & Larsson Gull book pages 26-32, the darkness of the primaries is a better fit for fuscus, whilst the size of the remnant mirror on p10 is a better fit for heuglini. I also feel that the total lack of dark streaking on the head or neck that is supposedly a feature of winter plumage in both contending taxa favours fuscus as that race has the least amount of streaking.

Mike Carter
30 Canadian Bay Road
Mount Eliza  VIC 3930
Tel  (03) 9787 7136




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