We had a quiet day on Wednesday but on Thursday 11th news of a Barred Warbler near Newford Duck Pond had us heading to the north east corner of St Mary’s. It was only a short hop from there to Trenoweth and Innisidgen which would offer reasonable views of the Eastern Isles which the Rough-legged Buzzard had adopted as its temporary home.
The Barred Warbler was a typically difficult bird and our best views were brief, sporadic and at long distance. While watching the Barred Warbler bushes a Mega Alert reported a Sora Rail on the Great Pool, Tresco. Several people left immediately but over the next ½ hour it became clear that the ‘Sora Rail’ was in fact a misidentified Spotted Crake, the bird we had seen on Tuesday.
With our fill of the frustrating Barred Warbler Peter and I decided to head towards the burial chambers at Innisidgen so that we could look for the Rough-legged Buzzard which had been seen again this morning over the Eastern Isles. There is a slightly raised area of grass above one of the burial chambers and we sat on the top with two other birders scanning towards the Eastern Isles some 1¼ miles away.
Soon enough a raptor rose into view and over the next ½ hour we had fairly prolonged distant views. Even though some closer photographs were taken of the bird as it made one of its trips over St Mary’s identification down to racial level would be difficult.
The North American race ‘sanctijohannis’ has occurred at least once in the western Palaearctic, in Iceland April 1980 although the true status of the American form is masked by difficulties in identifying the race. The weather, time of year, location and absence of any Rough-legged Buzzards on the east coats of Britain all strongly suggested, however, that this bird was indeed an American Rough-legged Hawk. There are no documented plumage differences to separate the American form other than subtle jizz factors such as sanctijohannis being slightly smaller, shorter and broader winged and stouter bodied. Many birders did suggest that the bird looked more Buzzard shaped and this further reinforced the American origin theory.
The clinching factor would be for a dark morph Rough-legged Hawk to turn up, this would be ultimate proof as the Western Palaearctic forms are pale phase only but in contrast 40% of eastern Canadian birds are dark phase. Unfortunately the Scilly bird was in the majority pale phase category and so it looks likely to remain in the probable Rough-legged Hawk category only. The trip back along the north east coast of St Mary’s provided us with up close views of a beached Common Dolphin corpse.