Monday, May 10, 2010

Amidst raging torrents

The meltwater from the peaks of the Iberian mountains charges down deep-cut ravines and valleys towards the sea. It provides an opportunity for birds capable of catching the many insects that live by the high-energy torrents.

Some birds, like the Spanish Yellow Wagtail (above), will breed in mountain streams high up. This one was at 1800 metres. This is the same species that we have met in the marismas, practically at sea level!

In the deep forest the gorgeous Grey Wagtail (above) replaces its cousin. But one species above all others is most at home in this challenging environment.

The Dipper (above and below) is the king of the torrents. No other bird exploits the mountain torrents like the Dipper, actually submerging itself and walking on the stream bed in search of invertebrates, Caddis Fly larvae being particular favourites. Every aspect of this bird is perfectly tuned to this particular way of life.

Our species, known now as the White-throated Dipper, is widespread on fast-flowing streams from Iberia, Ireland and the Hebrides eastwards to the Himalayas where it is replaced by the Brown Dipper that takes over eastwards to Japan and south-eastwards to northern Vietnam. The American Dipper is then found in North America down to Panama. Two species are found in South America: the White-capped Dipper in the north and the Rufous-throated Dipper in the south. From a common ancestor, the Dipper strategy has become almost wholly cosmpolitan in the mountain streams of the planet.

Photographs taken in Sierra de Gredos on 29th April and the Pyrenees on the 4th May, 2010

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