Thursday, 26 November 2009

The Yew Thrush

Mistle Thrush on a Yew
A closer shot of a Mistle Thrush
The Yew tree is laden with bright red, soft berries at the end of a church garden. On top of it is a bird, with a ratchety voice, guarding the precious sweet load, a Mistle thrush. Individual Mistle Thrushes become territorial during the winter months and defend their tree of intruders, either conspecifics or other thrush species. They eat their berries economically, feeding on the ground when possible, and leaving the berries for frosty days. The tree, thus, retains its bright berries for most of the winter. Only in very cold winters, will the Mistle Thrush be unable to enforce his possessions and must relent to the flocks of other hungry thrushes that want to feed. They are seen to defend Ivy berries, Mistletoe and, preferentially Holly trees.
Yew Berries. The only non-toxic part of the tree is the red aril surrounding the seeds, which thrushes help disperse.

More information

Barbara Snow & David Snow (1982) Long-term defence of fruit in Mistle Thrushes, Turdus viscivorus.  Ibis, 126: 39–49. doi: 10.1111/j.1474-919X.1984.tb03662.x

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