Rare visitor from Siberia and hot time for waders
WADERS, returning from more northerly breeding grounds, are beginning to move through Shetland now. On the 26th there were 32 knot, a green sandpiper and a curlew sandpiper at Virkie. Curlew sandpipers are scarce passage migrants, breeding in Arctic Siberia and wintering in Africa, Asia and Australia.
Autumn migration begins in late July in Scotland when small numbers of adults arrive, usually as singles. The main movement is from mid-August to mid-October when the records are mostly of juveniles. In Shetland, most curlew sandpipers are recorded from late August to mid September, with only a small number of records in July.
The curlew sandpiper is slightly larger than a dunlin and, at this time of year, the adults retain much of their brick-red under parts. On migration, they frequent coastal areas, especially mudflats, and also freshwater pools and marshes. The diet consists of invertebrates. The numbers of curlew sandpipers arriving in Scotland are very variable, being affected by poor summer weather at the breeding grounds and also by the amount of predation by Arctic foxes. In years when the lemming populations are low, predation by foxes is greater. Arrivals can also be influenced by weather conditions during migration.
A female two-barred crossbill, a rare vagrant from north east Europe or Siberia, arrived at Tony and Beth Gerrard’s garden at Sandgarth, Voe, on the 28th. Slighter in build, and more elegant in appearance than the common crossbill, the diagnostic features are two bold white wing bars. The two-barred crossbill breeds mostly in the taiga forests of Asia and North America, breeding in Finland and Sweden in some years. About 75 per cent of Scottish records are from Orkney and Shetland.
As fields are being cut for silage and, more rarely, hay, waders and gulls are foraging among the cut stems. By now territories are being abandoned and these birds are forming large post-breeding flocks. Common species in the fields around us are great black-backed, herring and common gulls, curlew, oystercatcher and redshank, along with starlings and blackbirds. There are sometimes rock doves and, at the weekend, a visiting friend noticed a wood pigeon sitting on the stone dyke surrounding the field. Much larger than the rock dove, the wood pigeon has a longish tail, distinctive white patches on the sides of the neck and a bold white wing bar. In Shetland wood pigeons are very scarce breeding summer visitors and fairly common migrants.
Having just returned from Norway, I was amazed at the profusion of colourful wild flowers growing along roadsides and in unfenced meadows and pasture along the Hardangerfjord. The national flower is the rosebay willowherb which forms dense stands. Growing up to 120cm the long leaves are narrow and resemble willow leaves – hence the common name. The dark pink flowers grow in stalked spikes and have four notched petals and four dark-coloured sepals. Rosebay willowherb is native to Shetland but is also a common garden escape. It spreads in two different ways which are both highly effective.
In autumn, the flowers develop into fruit capsules which split to release seeds with fluffy parachutes. These readily colonise disturbed ground. Once established the plant spreads horizontally by thick, woody underground roots which send up new shoots at intervals.