14 June 2010

The first occurrence of a species in Australia is usually something of a news event in birding circles and thrilling for the person who finds it. The first circulation of photos usually results in a flurry of excitement, with keen birders paying a visit. But it didn’t quite work out that way when Australia’s first Semi-palmated Plover or “Semi-P” was discovered at Broome Sewage Ponds in late October 2009.

Broome Semi-palmated Plover. As the season progressed, the bird started to moult its plumage and the very narrow line between eye and bill became apparent. This bird also has the white line above bill gape and, in this photo, the considerable webbing between the middle and outer toe, is clearly visible. Photo by Adrian Boyle.

Broome sewage ponds has long been a mecca for rare birds but in the past none of them have come from the Americas. Interestingly, it turns out that there have been some recent nesting records of Semi-palmated Plover from Chukotka, far eastern Siberia – perhaps a more likely source for the Broome bird. The site used to be reasonably accessible to birders, but for health and safety reasons, birders now have to view through the fence – or as some do, scope from the roof of a car.

Partly for these reasons, most of the birders who first saw the Broome Semi-P failed to identify it – they couldn’t see it well and in fact they assumed it was aLittle Ringed Plover which also been reported at about the same time. LuckilyRohan Clarke took a few photos nevertheless, and he got quite a surprise when he first viewed them on-screen. They showed a bird with sturdy build, big white supercilium, and no bold yellow orbital ring – it couldn’t be a Little Ringed. Ringed Plover seemed a much more likely possibility.

Nik Ward and Matt Slaymaker from Broome Bird Observatory had already developed suspicions that it was a Ringed Plover but it disappeared before they could confirm. And there the story might have ended there, had the bird not conveniently returned in December. Adrian Boyle managed to take the first detailed photos which were viewed by Jeff Davies and myself. Alarm bells started to ring. It didn’t seem quite right for a Ringed Plover either,  because the head looked small and round, the bill was a little short and more objectively, it had a curiously narrow dark loral stripe. Could this be Australia’s first Semi-palmated Plover, we thought?

The identification certainly wasn’t clinched at that stage, and a number of people were drawn into a detailed emailed identification discussion of the photos. Killian Mullarney and Richard Chandler, shorebird identification experts from overseas with a particular interest in the Semi-P problem, were particularly helpful. They explained a lot of the subtleties of relevance to the identification. While we did our armchair birding, the Broome locals (especially Adrian Boyle) and subsequent visitors did a grand job of feeding the discussion with increasingly good photographs and field observations. The identification characters began to fall into place.

1. There were initial concerns about the loral pattern. It wasn’t quite symmetrical, leading to concerns that there might be a bit of feather deformity or bleaching involved. Luckily the bird stayed around for long enough to moult from juvenile to non-breeding to breeding plumage. The latter two plumages symmetrically showed the classic loral pattern of Semi-palmated, perhaps the most compelling argument for this identification.
2. Toe-webbing was and is a headache – it’s very hard to see and it took a lot of work by the photographers to finally come up with images proving that the bird did have a respectable partial web between the middle and outer toe, and a tiny web between middle and inner toe. That’s supposedly diagnostic too, though the webbing does seem quite limited for a Semi-P, and the emailed discussions did leave us wondering how much variation there is in this very difficult character.
3. Initial reports that the bird called like a Ringed Plover turned out to be mistaken as the only Semi-P recording available at first was not a flight call. Provision of more suitable recordings from our friends overseas showed the call certainly wasn’t inconsistent with Semi-P.
4. Semi-palmated Plovers have a narrow yellow orbital ring in all plumages (only present in breeding male Ringed Plovers). This feature could be seen in the more detailed photos of the Broome bird in non-breeding plumage, and later became quite striking.

There were other intricacies too, but gradually a consensus emerged. The record has yet to be submitted to the Birds Australian Rarities Committee, but it looks like the documentation will be good enough to finally get the bird on the Australian list. It is a youngster, not yet ready for its first northward migration and it’s apparently still there.

A kind of “ringed plover” was also reported on mudflats of Finucane Island, Port Hedland, Western Australia on the 13th February by Marieke Weerheim. It looks like Pattie Parker may also have found one at Tuross Heads in NSW and another “ringed plover” was reported today from Corner Inlet. 2009/2010 may go down as the summer of the Semi-P. Perhaps you’ve a chance to find one where you go birding?

COMING SOON:

• Our identification guide to Little-ringed, Ringed and Semi-palmated Plovers
• Pattie Parker: How one woman managed to find two ‘seconds’ for Australia in one year!