Since the Yellow-breasted Bunting on St Agnes on Saturday we had seen a Blue-headed Wagtail and Red-backed Shrike on St Mary’s. The plan for Tuesday was to head to Bryher for the juvenile Rose-coloured Starling and then Tresco for the Pectoral Sandpiper.
Over the course of the last few days birders had been talking about two particular birds which were believed to be North American races of more familiar British birds. A Shore Lark had been found on St Agnes on Tuesday 2nd October before relocating to Tresco and a Rough-legged Buzzard had been touring the Islands since Monday 1st October. Both birds had arrived during a period of favourable weather for Transatlantic vagrancy and accompanied Nearctic passerines such as Rose-breasted Grosbeak in Devon and Baltimore Oriole in Ireland. There were also no ‘normal’ Shore Larks or Rough-legged Buzzards in eastern Britain yet.
The Shore Lark was believed to be of the migratory North American nominate form known as Horned Lark which breed in the arctic regions of eastern North America. The Buzzard was also believed to a North American race, known as Rough-legged Hawk.
An earlier specimen of Eremophila alpestris alpestris ‘Horned Lark’ had been collected on South Uist, Outer Hebrides in September 1953. This record has been subsequently deleted from the British List because of its moult state which indicated that it was taken in the spring and not the autumn. Any subsequently accepted nominate form would therefore be a first for Britain, albeit a race not a full species.
Having seen the Rose-coloured Starling on Bryher and with more and more birders suggesting that the lark was definitely worth seeing it was with growing excitement that we made the short 2pm boat trip from Bryher to Tresco. The tides meant that we had to land at New Grimsby and so we had a 1 mile walk to the opposite end of the island to Carn Near which was where the lark was being seen and also conveniently only 100 yards from where the 4:30pm boat would leave.
We passed along the length of the Great Pool and so took advantage of brief views of the Pectoral Sandpiper on the west side and a Spotted Crake on the east side. Without spending too long we hurried off towards Carn Near. Thankfully, the lark was a star performer often allowing approach to within a couple of metres. We joined a group of 20 or so birders and quickly had very good views of the lark out in the open on the short grass.
It would occasionally disappear under the overhanging heather at the fringes of the large grassy area but in the main allowed close and prolonged views. The Lark was very different to any Shore Lark I had previously seen. The face pattern was striking with a strong white supercilium behind the eye, a large grey ear covert patch and only a narrow pale crescent. The upperparts were a darker more rufous colour and together with the distinct chest spotting they contrasted with the clean white underparts. The median coverts were a rich pink-rufous. The outer webs to the tertials were also rufous.
Having seen the lark I wondered why we had taken so long to go and see a bird which is likely to become Britain’s first Horned Lark and a possible full species. This bird persuaded me that we ought to make an effort to see the potential Rough-legged Hawk on the Eastern Isles.