Can anyone identify this bird from our bird feeder please

What is your feeder covered with? Looks like moss.

The bird is a robin.

A sad-looking Robin. Maybe had a rough time, like a storm?

Possible infestation of feather mites.

Keep an eye out for a bald robin later in the year. I used to get one in my patch. The annual moult provided a new set, which then gradually 'disappeared' over the nex6 6-8 months.