A dawn chorus in spring

It happens every morning at this time of year - in the countryside and in towns - but how many of us have ever really listened to the dawn chorus? Why do the birds start singing before the sun even rises and does the early bird really catch the worm? RSPB wildlife adviser Ben Andrew talks to Jane Markham about the birds as they start to sing in an Oxfordshire garden, identifying the early risers and what you should listen out for.