Shovelers - unexpected migrants

by Malcolm Ogilvie

Several pairs of one of my favourite ducks, the Shoveler, are breeding on Islay this summer. The pure white chest of the handsome male aids identification at a long distance, even without the colourful combination of dark green head and neck and rich chestnut flanks and, of course, the very heavy-looking head and broad, spatulate bill.

Before the 1990s, the only breeding records from the island were probable ones in 1957 and again in 1970. Then, in 1992, soon after the RSPB had surrounded a rushy field on their Loch Gruinart reserve with earth banks and flooded it with shallow water, a pair settled and bred there, and here they have continued to breed ever since, increasing to the current 10 pairs or so, more than keeping pace with the increasing area of flood on the reserve where there are now four embanked fields. And as the population has increased, so the occasional pair has also bred on shallow pools elsewhere on the island.

Shovelers have a very distinctive feeding technique, swimming on the surface with their bill half-submerged (though sometimes with the whole head and bill completely underwater) and held slightly open. Water flows in at the front of the bill as they swim and then out again through the sides. Comb-like lamellae along the length of both mandibles trap any small seeds and invertebrates in the water and are periodically swept up by the tongue and swallowed. Sometimes groups of birds, up to 100 or more strong, gather into a dense pack and perform manoeuvres, turning in synchrony. The paddling of all these birds together stirs up the water and thus increases the amount of available food items.

Shoveler are present on Islay all year, as they are through most of Britain. This could lead anyone to think that they are sedentary birds, resident in the same area throughout their lives. However, ringing has shown that this is not at all the case. Britain's breeding Shovelers, numbering between 1000 and 1500 pairs, are migrants, setting off in the autumn for Spain, southern France and Italy. They are replaced by Shovelers from Iceland, Scandinavia and Russia. There are only 70-80 pairs breeding in Iceland, but they all appear to winter in Scotland, with perhaps a few in Ireland. The main European breeding range is in Russia, from temperate latitudes north to the sub-arctic, with a population numbering perhaps 80,000-90,000 pairs. The great majority of these winter in continental Europe, but the British wintering population hovers around the 10,000 level.

The two best places in the country to see Shoveler in winter are Rutland Water and the Ouse Washes, both have had counts recorded in the region of 1000 birds. Other excellent sites include Abberton Reservoir in Essex, the Somerset Levels and Loch Leven. Shovelers are not restricted to fresh water, as both the Burry Inlet in south Wales and the Swale Estuary in Kent are among the top ten sites in the country. Come the spring, these birds leave for their Russian breeding grounds leaving the wetlands free for our breeders returning from their Mediterranean winter sojourn.

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