Mallard

The Mallard is 56–65 centimetres (22–26 in) long (of which the body makes up around two-thirds), has a wingspan of 81–98 centimetres (32–39 in)
The breeding male is unmistakable, with a bright bottle-green head, black rear end and a yellowish orange (can also contain some red) bill tipped with black (as opposed to the black/orange bill in females).