8 Jan 2009

4 Jan 1989 - Tagus Estuary

Tagus Estuary

The Tagus estuary upstream of Lisbon is a vast intertidal zone of mudflats, bordered by 2,800 ha of saltmarsh, saline marshlands, mudflats, shallow lagoons and over 20,000 ha of reclaimed cultivated land. Beyond this is a hinterland of dry grass­land, cornfields, stone pine and cork oak wood­land. To the east some of this polder landscape has been somewhat modified by indust­rial and mili­tary instal­lations which pose a serious threat of pollution, but the estuary is still frequented in winter and migration time by over 70,000 waders including 75% of Europe's wintering avocet, plus calidrids and curlew and several thousand duck.

Some 22,850 ha of the saltmarsh, mudflats and islands are included in a reserva natural, where shooting and other forms of exploitation, except fishing, are forbidden. Access to the reserve for visitors is by road to perimeter then by footpath to points of interest, however there is no entry to three strict nature reserves ‑ Reserva Integral areas that are left for nature to get on with its own business and even scientists are allowed in only to monitor the situation.

We have a plan of action for the Tagus area, mapped out last night from the information in our books. Since we are coming from the north, we start with Lezeiroland, a vast area of cultiva­tion, and try to get to the estuary itself at Ponta da Erva. The road to this point is not signposted but we ask and are told we were going the right way. The road is a wide, solid farm track ‑ it needs to be for the tractors we meet on it are huge four‑wheel drive with double wheels affair, pulling an equally huge set of disc harrows. The farming here comes like a culture shock after several weeks of pocket handkerchief fields on mountainsides.

Cultivation is on a scale similar to East Anglia or the Netherlands, and the drainage ditches go hand‑in‑hand with huge irrigation sys­tems. Since Portugal joined the EEC in 1986 there has been a national urge to develop ‑ fast. The recent avail­ability of EEC funds now ensures the feasibility of many agricultural, industrial and other large scale development projects that could never have been attempted previously.

We keep following the track, guessing which way to turn at T junc­tions and, after about 10 km, we do reach the Ponta da Erva.

There are larks, finches and linnets in good‑sized flocks, plenty of house sparrows and thousands of common starlings. Snowstorms of gulls follow tractors in the distance. Half a dozen little egrets fly out of a ditch as we approach, and join others in the fields together with lapwing, golden plover and godwit. Three cattle egrets stalk through another field, occasionally one stops to stir up invertebrates with its foot, the way little egrets do in water. These birds have a peculiar rolling, goose‑like gait which distin­guishes them from little egrets at some distance.

A great grey shrike hunts from the tops of weed stalks in a dry‑look­ing pasture, and, having heard a crested lark call nearby, Jim studies the larks in that field until he finds it ‑ even with its crest down it looks a dumpier bird with buff outer tail feathers compared to the skylarks.

Until now we have seen cows used both for milk and as draft animals ‑ they don't bat an eyelid when traffic zooms past. Here we find bulls being reared for the bullfights and bull-running which are a traditional part of local fiestas ‑ and a field full of bull makes quite a lot of noise!

In one of the drainage channels we find moor­hen and little grebe, and near the sluice gate at the estuary end there is a kingfisher. Out on the mudflats are thousands of avocet, distinguishable in the evening gloom by their striking plumage, while other, browner, waders scurry about incognito.

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