Portland Bird Observatory
and Field Centre
Allen's Gallinule Porphyrula alleni
Allen's Gallinule has occurred once at Portland, on 10th February 2002, when a moribund individual was discovered by a member of the public on the West Cliffs at Weston - the bird died later the same day. This constituted just the second British record of the species
photo © Martin Cade
The occurrence was fully documented by Martin Cade in Birding World 15: 58-59 as follows:
As all reserve and observatory wardens will know, phone-calls from members of public about unidentified or sickly birds are something of an occupational hazard. Despite your protestations to the contrary, the mystery bird in the callers garden is always a rarity, and despite your being nothing more than a humble birdwatcher, the caller always accords you miraculous healing powers that the veterinary surgeons in your area have somehow failed to acquire from their years of specialist training. The trouble with these phone-calls is that you ignore them at your peril……
Early in the afternoon of 10th February 2002, Ashleigh Snaith was walking her dog close to the West Cliffs at Weston, Portland, when her attention was drawn to what appeared to be the corpse of a bird that the dog had discovered in rough grass ahead of her. As she approached, the ‘corpse’ moved its head and neck and she realised the bird was alive but obviously unwell as it made no attempt to stand up, let alone fly away. Being concerned for the birds welfare and curious to learn of its identity, she picked it up and took it the short distance to her flat before contacting Portland Bird Observatory.
By the time of my arrival, the bird had been placed in an empty shoe-box. The box-lid was duly lifted to reveal — to my astonishment — an Allen’s Gallinule! Unfortunately it was immediately obvious the bird was all but moribund: it was able to weakly lift its neck and open its eyes, but any other movement seemed beyond it. Examination in the hand revealed the pectoral muscles were completely wasted and the sternum could be felt protruding knife-like beneath the breast feathering; the lack any apparent elasticity in the skin also suggested the bird was suffering from extreme dehydration. The prognosis was bleak, and despite attempts to force-feed the bird with fluids — which it seemed too weak to even swallow — its condition deteriorated rapidly and it died an hour later. The bird weighed 82gms, which contrasts with typical weights of healthy birds of around 140-170gms, indeed the lowest published weight of a live bird is 102gms (Cramp 1980, Taylor 1998, Urban 1986). The specimen will be donated to the British Museum in due course.
Ageing and identification
The bird was in worn juvenile plumage, with the recent onset of post-juvenile moult indicated by the presence of a few glossy blue adult-like feathers on the flanks and upper thighs. The buff edgings to the feathers of the mantle and upper wing-coverts were heavily worn, and thus the upperparts appeared considerably less scalloped than indicated by photographs of European vagrants that have occurred earlier in the winter months (eg Birding World 15: 10). The only possible confusion species is the larger American Purple Gallinule, which in juvenile plumage has plainer upperparts and white undertail-coverts, as well as having less white elsewhere on the underparts.
photos © Martin Cade
Status and occurrence
There is only one previous British record of this, the only tropical African species to have occurred as a vagrant in the British Isles: a juvenile captured alive on a fishing boat off Hopton, Norfolk, on 1st January 1902. There are about 38 previous Western Palearctic records, with most also having occurred in mid-winter. Hudson (1974) demonstrated that the species straggled to the Palearctic in favourable weather conditions after dry season dispersal within Africa. The species breeds, at least in the northern tropics, during the wet season between July and September, and vagrancy is most likely to occur at the height of the dry season between December and March.
It seems likely from the birds emaciated condition that it had made a prolonged over-water flight immediately prior to reaching Portland: a surprising scenario considering the very disturbed westerly airstream dominant across Britain and north-west Europe at the time. However, during the preceding few days anticyclones were established across Iberia and north Africa and it may be conjectured that the bird left north-west Africa in favourable conditions during this period; an initial tail-wind would have pushed it out to sea to the west of Iberia, before it encountered strengthening south-westerly winds that drove it towards the Western Approaches and the English Channel.
Footnote
As a final scrap of ornithological trivia, it may be mentioned that the birds final journey brought it to within sight of Weymouth — the birthplace of William Allen, in whose honour the species is named. Allen, who also died at his hometown, was the commander of an expedition to the Niger River during which the type specimen was collected in September 1841 (Mearns 1988).
References
Cramp, S. Ed. 1980. The Birds of the Western Palearctic. Vol. II. Oxford.
Hudson, R. 1974. Allen’s Gallinule in Britain and the Palearctic. British Birds 67: 405-413.
Taylor, B. & van Perlo, B. 1998. Rails. Sussex.
Mearns, B. & R. 1988. Biographies for Birdwatchers. London.
Urban, E.K. et al. 1986. Birds of Africa. Vol II. London.
Biometrics
Details recorded in the hand were as follows:
Wing length (maximum chord) 157mm
Weight 82gms
Tail length 64mm
Bill length (to end of shield) 36.7mm
Bill depth at feathering 12.5mm
Bill depth at proximal end of nostrils 10.5mm
Bill width at feathering 8.7mm
Bill width at proximal end of nostrils 7.0mm
Tarsus length 53.2mm
Tarsus and toe length 120mm
Hindclaw length 13.1mm
Middle toe length 66.3mm
Wing formula (primaries numbered ascendently): P1 -25, P2 -4, P3 longest, P4 -3, P5 -8, P6 -15, P7 -24, P8 -33, P9 -40, P10 -48; wing-tip to longest secondary 50, wing-tip to S1 55, wing-tip to tertials 39.
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