The Dutch bird‑watchers at the Oostvaarderplassen had insisted that the cold weather was unseasonal and it would be gone in a few days; and now it is gone, but only to be replaced with fog and drizzle, typical north Atlantic winter weather.
Most of the province of Zeeland is taken up with the Delta area, the estuarine complex of the rivers Rhine, Maas, and Schelde. We start exploring at the inland end of the Delta where an area marked Biesbosch on the map looks promising. It lies at the confluence of the Rhine and the Bergse Maas which flow into Hollandsch Diep. Until 1970 this was a freshwater, though tidal, inlet. With the completion of the Haringvliet dam, tidal movement virtually ceased; the total variation in water level during the year is now only 1.5 metres and that is dependent mainly on the water supply and the wind.
The habitat is predominantly pasture with large areas of polders, creeks, marshland, swampy woodland and reservoirs. The area incorporates the Dortdsche, Sliedrechtse and Brabantse Biesbosch reserves. The natural vegetation of reeds, bulrushes and willow-osiers is being invaded by thistles and nettles. It is important for breeding waterfowl, and is at its best for birds in summer. Well, maybe we'll visit in some future summer. There is said to be good wader passage in spring and autumn, and lots of greylags and whitefronts in winter. However the small part we're able to explore by road today seems to be occupied by a variety of farm, woodland and water birds in small numbers.
Crossing the Haringvliet bridge onto the island of Overflakkee, we can see saltmarsh and birds so we stop at the first parking place and get the telescope out. Despite the poor visibility we watch lapwing, dunlin, teal, wigeon, swans, grey geese, gulls, pheasants, avocets, cormorants and thousands of mallard.
On the island itself, the coastal road takes us to the marina at the hamlet of Battencord. Several hundred knot roost along the shore, they are joined by another group flying low over the water, occasionally one or two break ranks and dart upwards 10 ‑ 15 metres with an erratic spidery sort of flight.
We often look at snipe in the hope of finding a jack snipe amongst them and today we are lucky. The small size and short bill of this one are emphasised by the comparative bulk and huge bills of the next few common snipe that we disturb.
Along the dyke I find a pair of dunlin wings. The flight feathers are grey, with a pale trailing edge to the inner secondaries; the greater coverts have white tips which form a narrow wing bar; the rest of the upper coverts are grey‑brown. The cinnamon and black scapulars are the only body feathers still attached, the colour suggests that the wings had belonged to a first winter bird.
The approach of brent geese is heralded by their grunting contact calls long before they appear out of the gloom. We estimate that six to eight hundred arrive in flocks of various sizes during the next half hour. Some land a few hundred metres further on in the mist. Others land on the water to preen and roost, or on the grass in front of us, chivvying each other as they settle down to feed. Although brents feed mainly on eelgrass which grows in shallow tidal water, at high tide they also eat grass, keeping in a tight bunch as they graze their way across the pasture.
Since the completion of the flood prevention scheme, fishing boats have not had direct access to the sea. The local economy has been encouraged to diversify with boat building and tourism becoming important. This evening we find a farm campsite offering basic facilities at rather cheaper rates than the commercial campsites we have been using ‑ campsites are taking a large chunk of our budget.
About the Delta area
After the catastrophic storm surge of 1953 which caused inundation of large areas of land, with nearly 2000 people and innumerable cattle killed, work began on a scheme to close off most of the estuarine branches to protect the land, solving problems of salt water incursion and providing a supply of fresh drinking water too. The mudflats were the winter home of thousands of waders but the creation of permanent water storage areas would force them to move. It would also destroy much of the local fishing industry. However, in the last two decades, changes in ideology have led to a government decision to give priority to the natural values of the area; changes in the scheme now mean there are areas of brackish, salt and fresh water, and the biggest estuary, the Oostschelde, remains tidal. Although the area was known to be of international importance for waders and wildfowl, information prior to the project was limited to two counts in 1966‑67 when there were 152,000 waders in September and 198,000 in January. Regular and more frequent counts began in 1972, when the Grevelingenmeer was enclosed. Some 40,000 ‑ 50,000 waders had used this particular area, 95% of them redistributed themselves over the remaining tidal basins. Total counts for the whole Delta appeared to show a slight overall increase in numbers, at least until 1980. Since April 1987 the construction of a storm surge barrier at its mouth of the Oostschelde has resulted in the loss of 37% of its intertidal flats; there do not yet seem to be any figures available for what effect this has had. The Roggenplat, a mud‑bank in the Oostschelde, plus another mud‑bank built up behind an island constructed as part of the dam, now form the main feeding grounds for the waders (ref: Lambeck, Sandee and de Wolf 1989).
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