Sure enough, one of the scourges of bird tables everywhere had swooped down onto the lawn and seized a Yarrow in its talons. Eh? A vegan raptor on a health kick? Or one seeking to augment the latest Greenfinch with Sunflower Hearts dish with a few choice herbs?
The truth was more prosaic. Though we did not see the intended victim, I suspect that it was a Dunnock, which had taken cover in the only place in the garden that appears to be hawk-proof, a low-growing compact shrub. We've been here before, see this post from November 2010.
To the unimaginative residents of Tense Towers, this plant is known simply as The Dunnock Bush.
Today's attack was less dramatic, and after rummaging about on the fringes of the shrub for a while, the Sparrowhawk gave up and left empty clawed.
A swift perusal of Wikipedia, showed that there aren't, in fact, any solely vegetarian raptors, thought the Palm-nut Vulture comes close.