Phil is eclipse plumage. All mallard ducks undergo a molting period in the summer in which they cannot fly. During this time, male wild mallards lose most of their ostentatious green feathers and look positively homely. Phil is a khaki Campbell cross with wild mallard, and when he goes into eclipse, he turns back to khaki.
It looks bizarrely moth-eaten for what was once fairly dapper duck with a green black head.
His concubines don’t seem to care that much: