I have noticed that one of my daily visitor's
A Mallard has got a pronounced limp
His knee joint is swollen
He is able to get about, eat me out of feed

and fly off, when the need arises
But tends to stand on one foot or lay down to feed
We are concerned that the limp, which has been noticeable for around a fortnight, is getting no better
Any suggestions Please?
Should i take him to a vet ?
Catching him would not be a problem as he comes to the door for food