Not sure here but there are so many other wildlife breed's Im not familar with.I would keep it warm and offer some non medicated chick food and water and maybe call you local wildlife managment for them to have a look.I don't think from the look's of it would be fair to the bird to keep it captive without a mate>I have never seen a "duck" with such a thin beak but sure there are some breed's out there.Please update us and let Us know how it goe's.Not a mallard but the color's somewhat resemble with the black and brown.Some local Agr./Forestry/wildlife sadly wont or do not have facilities to take them to but can offer advice on thing's.Give them a call I would for sure.Many people take in injured and lost wildlife and some can be very sucessfully returned to the wild and do great.