Unusual looking Robin

Unusual looking Robin

Observation - Unusual looking Robin - Global. Description: Observation posted on behalf of a niece who has this Robin as a regular visitor to her garden, apparently feeding young. She was wondered why the plumage looked like this; while a brood patch can result in some loss of feathers,this seems extreme to me.

Observation posted on behalf of a niece who has this Robin as a regular visitor to her garden, apparently feeding young. She was wondered why the plumage looked like this; while a brood patch can result in some loss of feathers,this seems extreme to me.

Any ideas please?