16 Jan 2009

7 Jan 1989 - a day in the cork oak woods

After studying the tourist leaflets last night we decide to visit Pinheiro ‑ 'it is integrated in the Natural Reserve of Sado Estuary. From there you have splendid view over the estuary ...' etc. The Ria Sado estuary, 50 km south of the Tagus, also comprises vast mudflats and saltmarshes, with several small reservoirs for irrigation purposes, and extensive ricefields and saltpans. Up to 20,000 waders winter here.

The leaflet suggests a driving tour starting with Pinheiro but, as the road signposted to there is a dirt track, we keep going expecting to find a sli­ghtly better road. The next road looks better but goes to the village of Monte Nova. We take that and find ourselves going through several kilo­metres of cork oakwoods. We stop several times ‑ there is very little traffic to worry about, and see hoopoes feeding under the trees. On the other side of the road sheep graze the woods and a couple of cattle egrets hitch rides on their backs.

Cork oak is extensively grown in southern Portugal, which produces about one‑third of the world's cork supply. It is also grown in parts of Spain. The oakwoods often form open park‑like forests which may be regularly cultivated or grazed, as here, or a dense scrub may be allowed to develop among the trees, as we found in other areas. Many of the great cork oak woods were developed during the last century by large estates from waste land which was previously covered by matorral, a low‑growing mediterranean scrub habi­tat. The cork bark is harvested every seven to ten years, and the recently harvested trunks were bright orange and looked rather naked. Occasionally we came across a huge stack (fifty or more metres long by two metres high and five wide) of recently harvested cork. And there were large lorries carrying the bark to process­ing centres.

A flock of what look like grey parakeets fly ahead of us, but through the binoculars they turn into azure-winged magpies, their colour not showing well in the overcast light. They feed under the oaks, mostly on the ground but sometimes hover­ing to get at something just above head height. Although these magpies do not seem quite as noisy or quarrelsome as their common cousins, they do have buzzing contact calls which became a higher and higher pitched excite­ment call when a motorbike gets too close for their liking. They tend to fly through the canopy, rather than over or under, and their movements are not easy to follow.

Further along the road we stopped to watch another flock of about fifteen birds feasting on the fruit of prickly pear cactus which is fairly com­mon here. Cactuses were brought to Europe from America as ornamental plants in the late sixteenth century. The prickly pear grew so well and so thickly that it was used to make hedges that were impenetrable to both men and livestock. The thorns are actually leaves modified to discourage grazing animals, while the 'leaves' are really stems which have been modified into water storage organs. The fruit is purple and somewhat pear or fig‑shaped and spiny. It spread so fast in north Africa that later travellers thought it was native there and it become known, erroneously, as the barbary fig. It ripens at the end of summer and is edible for humans as well as magpies. Any bird on a fruit had to keep an eye on others hoping to usurp it, feeding was easier and more relaxed when each bird had found itself a meal.

While watching the magpies we become aware of other sounds nearby. Most of them come from a great grey shrike calling from near the top of a tree ‑ it is the first time we had heard any noise from them. The calls have a repet­itive rhythm, described as shek‑shek in the book, but include a variety of sounds from whistles to buzzes, and even a buzz-whistle.

Back onto the main road again, and this time we do take the dirt track to Pinheiro. It follows most­ly through oakwood and, since there is virt­ually no other traffic, we are able to go slowly and stop anywhere. After some kilometres we come to a small lake, well populated with mallard, coot and moorhen. A flock of a couple of thousand birds take off from the fields beyond ‑ they act like starlings but a close look showed them to be pigeons, we had not seen them in quite such num­bers before.

Even more surprising is finding crag martins hawking over the pond. Although many birds do remain in their mountain breeding habitat for the winter, some migrate to lowlands where they take up resi­dence in the vicinity of swamps, marshes and lakes. They have even been recorded dipping to the water apparently to take insects from the surface.

There are some strange looking pine trees in clearings amongst the oaks ‑ strange because they have short thick trunks and rounded or spread­ing crowns, these were stone or umbrella pines (not to be confused with the stone or arrolla pines in the Alps). The pine nuts are edible, and found as piñons especially in Spanish cuisine, and the cones may be used as fuel.

The road ends at the village of Pinheiro but are were tracks leading from the village along the estu­ary. Around the villages there are rice fields (it is an important crop in this area), reduced to stubble at this time of year. The stubble is left quite long and the main birds there seem to be gulls, egrets, storks, larks and snipe.

Passerines tend to stay well hidden, but we catch sight of a blue­throat feeding between the rows of stalks. It turns towards us and we see that it is a female before it flies off. The scrub along the edge of the fields holds sardinian warblers and waxbills.

We emerge on the estuary close to an area of saltmarsh standing just above the high tide. A marsh harrier, disturbed by our appearance, in turn disturbs thousands of waders in the salt­marsh. They are mainly dunlin and grey plover close to the shore, and curlew and godwit further away. As the birds settle again the smaller waders pile onto tiny islands of spartina, perching on stalks and on each other trying to roost. Somehow the saltmarsh soaks them up like a sponge.

Along the shore a flock of a hundred serins, goldfinches and linnets feed on the seeds of shrubby seablite, looking like yellow fruit weigh­ing down the branches.

As we pass a stack of cork by the lake on our way back along the track, there are two little owls on the ground nearby. They watch us for a couple of minutes, then one flies into a tree, while the other squeezes itself out of sight between the sheets of bark ‑ they must have had the best insulated home available!

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