Friday, 2 April 2010

Mistle Thrush well into breeding season

The local Mistle Thrushes have been singing for some time now. Indifferent to the wind and rain of last month, hence the local name of ‘storm cock’, their song has been heard on and off for many weeks. I suspect that they are now incubating a clutch of eggs or, possibly, feeding young chicks. Mistle Thrush nests are either placed up against the trunk of a tree, in the crook where branch meets trunk, or further out in a fork on a horizontal branch.

The nest itself, like those of certain other thrushes, has several distinct layers to its construction. An outer layer of loosely woven grasses and roots is held together by a layer of mud and rotten wood. Finally, the nest cup is lined with finer grasses and, occasionally, pine needles, the latter possibly serving as an insect repellent against nest parasites. In my opinion the nest is less tidy than those of Blackbird or Song Thrush and sometimes incorporates bits of paper or plastic.

Mistle Thrushes seem to do well in suburban areas, as does the Song Thrush, though both species have undergone significant declines in their populations since the 1970s. They are, however, often overlooked and many casual observers regard the two species as being just one – the thrush. While the Song Thrush (smaller than a Blackbird) is a bird of warm tones, the Mistle Thrush (larger than a Blackbird) tends to show colder tones, with pale greys and browns. One of the best features to use when separating the two species is the shape of the spots on the upper part of the breast. On Song Thrush these are shaped like upside-down arrowheads, though they become more rounded and slightly elongated on the flanks. In Mistle Thrush the spots are round in shape and they often coalesce to form darker patches on the flanks.

Later into the year you may well see family parties of Mistle Thrushes feeding together. These small groups of birds remain wary around humans and will often fly away at your approach, uttering an alarm call that sounds like an old football rattle. Perhaps surprisingly, given their wary nature, Mistle Thrushes can be rather noisy around the nest, giving its location away to human observers and potential predators alike. Mind you, the Mistle Thrush is a formidable bird and pairs will not hold back when attempting to drive potential predators away from the nest. You should also keep an eye out for adult Mistle Thrushes feeding on open areas of short turf and then carrying food back to hungry young. Although the young remain in the nest for just two weeks, the adults will undertake more breeding attempts throughout the summer.

No comments:

Post a Comment