Sunday, March 25, 2012

Blackbird vocalisations

Last weekend I was up in Ayrshire and early on Sunday morning I surveyed Dean Castle Country Park for Nuthatches. Later on I made some recordings of a confiding male Blackbird (Turdus merula) who wasn't keen to fly around too much as a pair of Sparrowhawks (Accipiter nisus) were displaying over his territory. The female hawk was also regularly coming down and flying through the sub-canopy. The diagram below shows a summary of some of the calls and song recorded - click for bigger images.

This is the classic song of a Blackbird and my favourite sound of early spring. Although it is most often uttered from a high, prominent perch, this male was singing about three metres up in thick woodland.

This high-pitched alarm call is often referred to as the 'hawk alarm call' and these down-slurred, pure-tone notes between 9 and 7 kHz were produced in response to the Sparrowhawks.

Another alarm call is the low-pitched "chook-chook-chook" sound. This male produced it on the ground when a dog passed by on a nearby path.

Still on the ground, the same male began singing this unusual song. While it resembled sub-song in structure (and with some similarities to a Song Thrush), it was uttered at loud volume on the open woodland floor before gradually changing back into standard song.

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