THE BEGINNING of the month brought a fall of migrants with widespread records of willow warblers – up to 25 being recorded at Sumburgh Farm.
Willow warblers are common passage migrants, moving through Shetland in spring and autumn. In autumn the immatures have pale yellow underparts and the upperparts are brownish-green with a distinctive pale eyestripe. They are lively and restless visitors to the garden, flitting around trees and bushes searching for insects.
Other species recorded included pied and spotted flycatchers, a reed warbler, icterine and garden warblers, wrynecks, common redstarts, whitethroats and lesser whitethroats, swift and kestrel. At Cunningsburgh there was a great spotted woodpecker and a cuckoo.
Cuckoos are scarce passage migrants and have been recorded from April to October but most are spring records. Juveniles are rusty brown and slate grey on the upperparts, with white underparts barred with brown. The flight feathers have narrow white fringes and there is a white patch on the nape of the neck. In flight the head appears small and the tail long and it is sometimes mistaken for a small falcon or hawk. The cuckoo’s diet is mainly caterpillars and other insects.
Waders are still on the move with records of greenshank, ruff, knot and sanderling this month. There was a flock of 60 eiders off the south of Bressay.
Male eiders gather in flocks in June, and, from early to mid-July the flight feathers are replaced, so that the birds are flightless until late August and into September. Non-breeding females, and those eider ducks which have been unsuccessful in rearing young, join the pre-moulting flocks in June, and successful females and juveniles join the moult flocks during July and August.
My moth trap has been continuing to capture high numbers of moths with up to 140 small wainscot and 90 large yellow underwings recently. Most evenings there are 14-16 different species.
George Petrie caught a convolvulus hawkmoth and a herald at Ocraquoy, Cunningsburgh this week. The convolvulus is an extremely large moth with ash-grey, marbled and streaked forewings and a thick, pink and black striped abdomen. It has a very long coiled tongue and feeds on the nectar from tubular flowers like honeysuckle, lilies, petunias and tobacco flowers.
George also had a herald, another migrant, in his trap. The herald is often seen on sugar or feeding on flowers and ripe berries after dusk, but it does come to light also. It is a beautiful and unmistakeable, medium-sized moth with grey-brown scalloped-edged forewings marked with yellow and red areas. Two distinct white crosslines traverse the forewings with the broadest line near the tips.