Blackbirds feeding young behaviour?

There's a pair of blackbirds busy feeding their young in my garden. Every time they gather food, before returning to the nest the land on a nearby fence and just stand there looking around for a bit with the food in their beak (perhaps checking for predators?). What surprised me is that the male blackbird will always sing a few notes before taking the food to the nest whereas the female blackbird remains silent. What's the purpose of this?