I walked under a bush yesterday (Urban roadside bush in leafy north London, 09:30 on a damp but not rainy day, January 13th 2020) and heard a blackbird singing in that bush, really quietly. I only heard it as I walked directly underneath, no more than a meter from the bird. It was dark brown, rather than black, with a dark beak and it was singing a complex song but so quietly, one might think it was practicing! Is that possible? Do birds practice quietly? What else could it be doing?
Hi Johnny, THIS may give you a few answers to your question. Robins also sing very quietly at times - at "whisper" levels like is mentioned in the link.
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Regards, Hazel