21st July 2018
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Rare warbler among the visiting vagrants

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A MELODIOUS warbler, a rare vagrant from Southern Europe, was at Sumburgh Head this week, first being recorded on the 6th.

In Scotland it is extremely scarce but is recorded annually with over 50 records, 75 per cent of these coming from the Northern Isles.

First recorded in 1955 in Shetland, there are under 30 records, mostly of first winter birds in autumn.

Melodious warblers breed in southern and western regions of Europe and in North East Africa, wintering in Africa south of the Sahara desert. This species resembles an Icterine warbler but is pale buff-yellow below and brown-grey above.

Also in the Sumburgh Head area this week were common and two-barred crossbills (with 18 of the latter, including two brilliantly coloured adult males, on the 9th), a pied flycatcher, a red-backed shrike and a swift.

Elsewhere there were two grey wagtails at Hoswick, a marsh harrier in Dunrossness and a cuckoo at Aith.

There was a snout, the fourth record for this moth in Shetland, trapped at Scatness on the 5th.

Kenny Jamieson reported seeing a cinnabar moth in a small plantation in East Burra during the first week of July. This is a very striking moth with blackish forewings with a long red stripe along the edges of the wing and two red spots along the outer margin. The hindwings are red with a narrow black border. This species has been recorded at least once before but is a rare migrant.

A course on an Introduction to Invertebrates, led by Pete Board­man, took place on the 11th and 12th. There are approximately 27,000 species of land and freshwater invertebrates in the UK with the largest group being Diptera (flies) of which there are approximately 6,900 species.

Many UK species have not been identified because reliable keys to the lesser known groups have not been updated or developed, and there are only a handful of experts able to identify some of the families. About six new species are added to the UK list each month Pete specialises in craneflies and there are 230 species of cranefly in the UK with 30 on the Shetland list.

The commonest is Tipula paludosa (daddy-long-legs) which is associated with dry and damp grassland. These long-legged, gangly insects hatch from larvae, known as leatherjackets, which live in the soil. After emerging, the adults only live for about two days.

The female cranefly is larger than the male and has a pointed reddish-brown abdomen, while the male’s abdomen has a square-ending. Starlings are one of the main predators of leather jackets in grassland and lawns, whilst moorland birds, such as golden plover, eat the larvae and adults of the cranefly species found in these habitats.

We also found Limonia nubeculosa, a species which is found in damp, shady environments where it breeds in moss. This species has distinctive spotted wings and striped legs. Another common species of lochsides and beside burns is Tipula lateralis breeding in wet substrates, such as mud or moss. This species has a grey abdomen with black bordering stripes and has striped wings.

During the course a new species of hoverfly for Shetland was identified. This species was found at Kergord and is associated with decaying pine wood.

In the UK there are 1,000 species of invertebrates which are associated with dead wood habitats, a high proportion of the total. More of the specimens obtained await identification, thus further increasing knowledge of the Shetland invertebrate fauna.

The next course is Autumn Birds, led by Paul Harvey on 6th and 7th September. There are still a few places available and anyone interested should contact Paul on (01595) 694688.

A basking shark was seen at the Dale of Walls on the 3rd and at Banna Minn, Burra on the 4th.

On the 12th there was a basking shark off Trondra. The second largest marine fish in the world (the whale shark is the largest), the largest record is a length of 12.3m but females average 8.9m and males 6.5m.

A basking shark cruises just below the surface at a maximum speed of 4mph, with open mouth, filtering out plankton. The plankton is trapped by sticky mucous-covered gill rakers and then consumed in one gulp. About 2,000 tonnes of water are pumped through the gill rakers in an hour. We could see the dark dorsal fin and occasionally the tail as it moved slowly up the voe feeding.

Joyce Garden