Duck Soup ingredients- (i) a paring of Wigeon

A grazing specialist, Wigeon first rely on pondweeds and algae, becoming more reliant on grasses as a winter progresses. Very much a generalisation, as some individuals might favour grassland, while others might rely almost exclusively on the estuary itself, but certainly between September and November, the vast majority will favour the flats, then switching in large numbers from saltwater to freshwater vegetation from November onwards, as volume of algae drops. What is left is also then deteriorating in quality, making grass is a better energy source, especially when the weather is mild and the growth continues. (This winter it has been interesting to see Wigeon exploit a newly seeded growth on one stretch close to the sea wall.)

Providing there is no hard weather around the time of this switch, although a birder might count fewer Wigeon loafing on the flats, total numbers on the estuary actually remain roughly the same. Birds can choose to feed 'inland' during the day at sites such as Ham Green and Chetney. Although there is a big turnover of individual Wigeon during an autumn as birds use the Medway to stage and refuel before continuing south, unless there is severe weather, perhaps heavy snow denying easy access to food, there are no routine cold-weather movements, just localised redistributions. Individual birds will often use the same areas at similar times in subsequent years.

The over-simplistic map below illustrates autumn/early winter feeding/loafing areas (yellow circles) with an indication of usual movement on the rising tide. They will loaf on or near algae beds, then retreat toward safer areas as needs be.

After the switch to grasses/seed, Wigeon will often feed inland (red squares), retreating to islands when disturbed. If the islands are being shot that day, they might make a small adjustment to another part of the complex (the Greenborough complex is large, the number of guns usually small) or ride out the tide/ sit out on a flat.

To find good numbers in late August/September, look to the algal beds offshore close to the main channel; Copperhouse, Ham Ooze and Blackstakes often provide the largest flocks. Come mid-winter, most of the birds on the mud are loafing; do not forget to check the viewable parts of Ham Green, Barksore and Chetney.

From personal experience, the present five year average peak from WeBS totals of 1,932 Wigeon for the whole of the estuary is passed routinely by just the southern shore. Incomplete counts at the early part of the autumn passage miss the early peak, and later counts suffer from the 'weekend effect'. Shore-based counters will have low numbers on land, thanks to the level of weekend shooting (Friday through Sunday), with many of these birds displaced to the island complexes, which are for the moment usually counted by boat earlier in the week.