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Monday, 21 September 2009

TAIGA AMERICAN WHITE-FRONTED GEESE in OXFORDSHIRE


BLENHEIM PALACE PARK LAKE (OXFORDSHIRE)
(with Phil Barnett, Paul Wren and partner)

The two adult PACIFIC WHITE-FRONTED GEESE, initially seen in Oxfordshire at Otmoor during the spring of 2004, were present for their fourth day today, showing extremely well along the access road at the far west end of the Palace Lake. They were consorting with the large moulting flock of ornamental geese, predominantly Atlantic Canada, but also including 55 Greylag and 7 Bar-headed Geese. The birds were very distinctive and interestingly vocal and perhaps the wariest individuals in the flock (see Adam Hartley's image above)

The juvenile SABINE'S GULL was still present and viewable from the bridge whilst the long-staying GARGANEY, a single COMMON SHELDUCK, an impressive 157 GADWALL, 4 NORTHERN PINTAIL, 42 Common Teal, 15 Shoveler and 11 Eurasian Wigeon were noted. There was also a large pre-roost of Black-headed and Lesser Black-backed Gulls.

The pair of White-fronted Geese had previously visited Otmoor RSPB as first-winter birds from 3-22 May 2004 (Graham Coleman, Phil Barnett, et al). Both birds (perhaps a pair) are large and long-billed, approaching Greylag in size, with particularly thick legs and neck. The bill colour is predominantly pale pink but with a distinct orange tone to the base of the gander's. The white frontal shield of both birds was extensive and wide (especially above the forehead) whilst both birds exhibited a thin yellowish-buff eye-ring, more pronounced on the male. The general body plumage was greyish on the face and foreneck, with a darker crown (the lower edge of which cut through the eye) and hindneck. Also, the black band behind the white blaze formed a very broad vertical line running from the lores, down to the chin, where it broadened to a rhick dark throat line.

The upperparts were drab grey, with typical pale grey fringes to many of the feathers, with paler sepia-brown underparts heavily marked with bold black patches. The tail was extensively dark brown but significantly tipped with a narrow white terminal band

The legs and feet were orange and noticeably thick.

WHITE-FRONTED GOOSE TAXONOMY

The White-fronted Goose complex occupies a circumpolar breeding range. In the Palearctic, it breeds from the Kanin Peninsula in NW Russia eastwards to far east Siberia, whilst in the Nearctic, it nests in Alaska and Arctic Canada eastwards to NW Hudson Bay, with an isolated population in western Greenland. All forms of White-fronted Geese are highly migratory and spend the winter in comparatively mild latitudes well south of the breeding ranges.

Generally speaking, there are six widely recognised forms of White-fronted Goose and instead of being based on morphological characters alone, recent taxonomists and researchers have proposed that subdivision based primarily on the geographical distribution of the main populations is perhaps more preferable. On this basis for example, Mooij & Buckler (2000) in their ''Reflections on the Systematics, Distribution and Status of Anser Albifrons'' published in Casarca 6: 92-107 recognise the form albicans as a separate type. Currently, the UK400 Club utilises the following treatment, recognising three separate forms

1) EURASIAN WHITE-FRONTED GOOSE (Anser albifrons) which breeds in Russia tundra, from the Kanin Peninsula to the Tamyr Peninsula and winters in Europe.

2) PACIFIC WHITE-FRONTED GOOSE (Anser albicans) consisting of several 'sub-species' although the taxonomic position of C and D is unclear and they may well relate to an additional closely-related species-pair - TAIGA AMERICAN WHITE-FRONTED GEESE-:

A) ASIAN WHITE-FRONTED GOOSE (Anser albicans albicans) breeding in Siberia tundra between the Khatanga River and the Bering Strait and winters in SW Asia

B) NORTH AMERICAN WHITE-FRONTED GOOSE (Anser albicans frontalis) which breeds on tundra in western and northern Alaska eastwards to at least Queen Maud Gulf and winters in western North America, Mexico and Texas. This form may be legitimately segregated into three sub-populations; one breeding from northern Alaska to Canada (and wintering from Texas to eastern Mexico), another breeding in western Alaska and wintering in California and a further breeding in SW Alaska and wintering south to western Mexico.

C) GAMBEL'S WHITE-FRONTED GOOSE (gambeli) breeding in NW Canada, from the Old Crow Flats to Repulse Bay and wintering in eastern Mexico, Louisiana and Texas.

D) TULE WHITE-FRONTED GOOSE (elgasi) breeding in at least the Cook inlet in southern Alaska and wintering uniquely only in central California. Also distinctly, it breeds on taiga.

3) GREENLAND WHITE-FRONTED GOOSE (Anser flavirostris) breeding in western Greenland and wintering in Ireland and Scotland. It favours glacial plains and alpine bogs on high plateaus to nest.

In all reality, it is most likely that the two Blenheim Palace Lake birds are GAMBEL'S WHITE-FRONTED GEESE, an individual of which has been previously identified in Britain at Slimbridge WWT, Gloucs, between January and March 1977 (Peter Scott et al).

Phil Barnett, utilising much input from Richard Millington, Ian Lewington and Martin Reid, documented the 2004 Otmoor occurrence in detail in Birds of Oxfordshire 2004: 90-96. Two birds meeting the same criteria had previously been seen in Portugal that winter and it was considered at the time that these had migrated north to Oxfordshire in late spring.

We now have the dilemma of not knowing where these two birds have been in the intervening five years since their initial finding. Have they been in Oxfordshire all of this time moving between private locations with ornamental geese or are they merely returning birds from elsewhere? Were they not escaped birds from a local collection all along? Enquiries within the wildfowl trade suggest that Taiga White-fronted Geese are almost unknown in captivity (Lee G R Evans).