TWO star birds for the North Isles last week were an aquatic warbler at Skaw, Unst, on the 4th, and at least four two-barred crossbills, scattered across the isles. Although only a local rarity, the aquatic warbler was the first record for Unst. An acrocephalus warbler, this species is in the same family as the slightly more familiar sedge, reed and marsh warblers, but infinitely scarcer.
Breeding from Germany right across eastern Europe, aquatic warbler has suffered huge population losses, mainly due to habitat loss caused by land drainage, and is now a globally threatened species. Initially resembling a pale sedge warbler with streaked brown upperparts and paler underparts, its head pattern is its most distinctive feature, with not only blackish and pale striping through and above the eye but a noticeable pale longitudinal stripe on the crown.
The bulk of the two-barred crossbills visiting Shetland just now have been on Mainland, but at least four were found in the North Isles last week, singles at Tresta, Fetlar and Mid Yell, with two in north Unst.
The first record of this species in Shetland was of two – a female and an immature – shot by Henry Saxby at Halligarth, Unst, on 4th September 1859, so it’s been a long wait for Unst’s second record.
However, an adult female was on Fetlar in August 1987, part of a small influx. This is an irruptive species, normally breeding far to the east of us, but if a successful breeding season is followed by food shortages, then the population starts moving, sometimes long distances.
Other migrants last week included a common rosefinch was at Skaw, Whalsay, on the 5th, the day after a freshly dead quail was found on the same island, this time at Hamister, while a Sandwich tern flew past the Houb, Whalsay on the 9th. Baltasound had a grey wagtail on the 9th.
Two significant counts have taken place recently. Firstly the gannet colony on Hermaness, where 24,353 pairs were counted, a phenomenal increase of 35.8 per cent since the last count in 2003 when 15,633 pairs were counted. Certainly gannets, with their ability to fly long distances to find food, do seem to be bucking the downward trend affecting many seabirds.
The other count was of the fragrant orchids on the Keen of Hamar, which appear not to have had a very good season this year, with only 31 flowerheads. Numbers do often fluctuate from year to year, no doubt linked to weather conditions, but it is possible that a few were missed as the count was made a bit late this year.