Have you heard the blackbird’s sub song?

Tucked within the winter flowering honeysuckle in front of my house a blackbird is practising his song.  If you listen carefully you can hear him singing very quietly,  getting ready for the spring day when he starts singing out loud,  to attract a mate and establish his 'patch'.   He does not seem at all afraid when I approach the bush .  Perhaps he thinks I cannot see him!   He practises for hours on sunny winter days.   This is called a sub-song.  Have you heard it? Margaret Pitt February 2016