Week for vagrant warblers
VARIOUS species of warblers have been recorded this week including reed, wood, willow, garden and booted.
The booted warbler, a rare vagrant from eastern Europe, was found by Roger Riddington at Sumburgh Farm on the 20th. It is a small warbler, buffish-brown above with a short, pale eyestripe and can be tricky to identify from other similar species.
The “booted” part of the common name refers to its darker feet, contrasting with brownish-pink legs, and this characteristic can be difficult to see in the field. Booted warblers breed in eastern parts of the Baltic, north western regions of Russia, east to Mongolia and south to the Caspian Sea, and winter in India.
The species was first recorded in Britain on Fair Isle in 1936, and most Shetland records have been between late August and mid-September.
Other passerine migrants recorded were whitethroat, chiffchaff, stonechat, pied and spotted flycatchers, turtle dove, grey wagtail, kestrel, swifts, swallows and sand martins. A wryneck was also found dead at Exnaboe.
Large numbers of waders are passing through with 80 ringed plover at Melby; and 93 knot, 30 sanderling, three black-tailed godwit and a ruff at the Pool of Virkie.
Juvenile ruff have deep buff underparts and bold blackish-brown upperparts with warm buff edges to the feathers. Ruff are fairly common passage migrants, with most recorded in August and September. There have been annual autumn records since 1970.
Sea watches have produced records of pomarine skuas and shearwaters with seven sooty shearwaters counted off Sumburgh Head on the 24th.
On the 26th six sooty, 12 manx and a great shearwater were observed off Eshaness. The great shearwater is a rare migrant from the South Atlantic. They mainly breed on Tristan da Cunha, migrating around the Atlantic Ocean outside their breeding season, which brings them into the north east sector in autumn. Sooty and manx shearwaters were also recorded off Sumburgh Head and Maywick on the 26th.
Vivian Clark found a death’s head hawk moth resting on the wall of his house in Brae on the 20th. This is the largest and heaviest moth seen in Britain, with forewings measuring around six centimetres and weighing about seven grams.
This species has dramatic colouration and markings, with marbled blue-black forewings contrasting with yellow, dark-banded hindwings and abdomen. Its size and skull-like marking on the thorax are unmistakeable.
When disturbed, the moth makes a squeaking sound like a mouse, which is produced by air vibrating structures in its proboscis.
The death’s head hawk moth is strongly migratory, travelling northwards from Africa. Some breed in Britain, laying their eggs on potato plants or species of nightshade, and their offspring are on the wing in August and September.
Most death heads are recorded in south and east England but they have been found in most parts of the British Isles, including on oil rigs in the North Sea. They are mostly nocturnal but can sometimes be found at rest during the day.
In folklore, the death’s head hawk moth was widely regarded as an omen of death because of the skull-like marking.