Simply two thrushes breed throughout a lot of the Iberian Peninsula: The Eurasian Blackbird (Turdus merula) and the Mistle Thrush (Turdus viscivorus). Two others have a restricted breeding distribution within the north: Song Thrush (Turdus philomelos) throughout the Cantabrian Mountains and the Pyrenees, and Ring Ouzel (Turdus torquatus) within the Pyrenees. Come this time of 12 months and the sample modifications radically because the peninsula is swamped with enormous numbers of migratory thrushes.
Within the south, the dominant migratory thrush numerically is the Tune Thrush, arriving in giant flocks with substantial numbers crossing the Strait of Gibraltar onto Morocco. These birds are largely of Scandinavian, German, Dutch and Baltic origin. Redwings (Turdus iliacus) additionally attain the south however in smaller numbers and by no means within the giant flocks that winter additional north in Iberia. These birds additionally attain Morocco. Scandinavia is the primary supply of those Redwings. Fieldfares are a lot scarcer within the south of Iberia than the north, the place they type enormous flocks, however do I see them usually within the increased mountains near Gibraltar. They’re additionally of Scandinavian origin and a few attain Morocco.
Ring Ouzels inform us a special story. Of their case the mountains of the Iberian Peninsula, significantly the south and east, and Morocco type a serious wintering stronghold. It’s fascinating that two sub-species meet right here within the wintering grounds and could also be seen alongside one another within the mountains: the darkly-coloured nominate sub-species, which breeds within the British Isles and Scandinavia, and the heavily-scaled alpestris from the mountain ranges of the Pyrenees, Alps and presumably different central European mountains.
The 2 species which have giant and widespread breeding populations throughout the peninsula – Blackbird and Mistle Thrush – even have their numbers augmented in winter by migrants from the north. I recall ringing thrushes within the Organic Reserve at Doñana (SW Spain) and catching Blackbirds which had been clearly migratory. Most noticeable had been their lengthy and pointed wings, which contrasted with the shorter, more-rounded, ones of the native birds. These migratory blackbirds come from central and north-western Europe – Germany, France, England, Switzerland. I generally come throughout Mistle Thrushes in uncommon places presently of 12 months and I attribute these to migratory birds on passage. These birds attain the southernmost limits of the wintering vary in Morocco the place they might combine with the native sub-species deichleri that’s reported to carry out its personal altitude actions, to decrease floor, within the winter.
A key characteristic of the thrush wintering within the Iberian Peninsula is the dependence on fruiting shrubs. Within the mountains they’re typically related to stands of juniper or hawthorn. Rowan are additionally favourites. Fieldfares are keen on apples. At Doñana, we’d ring Tune Thrushes, Redwings, Blackbirds and even Ring Ouzels within the autumn and winter. They had been additionally in juniper stands, this time proper down on the coast. A number of recoveries of Redwings and Tune Thrushes confirmed the extent of the nomadic actions of those thrushes in the course of the winter, birds ringed in Doñana in November having traveled again north to the Pyrenees by January. As soon as once more, the thought of a wintering floor, so ingrained in our minds, is just not one which the birds themselves appear to subscribe to! It appears clear that the actions observe the ripening of the fruit, though how they know and discover them is a little bit of a thriller.
