The Cape (or South African) Shelduck, as its name suggests, is native to southern Africa.
The male looks like a Ruddy Shelduck with a light-mid grey head.
The female is like a Ruddy Shelduck with a dark grey head and a white face. They pair for life but females outnumber males.
Adult male
Adult female
Juvenile (with mallard)
"Duck!"
"Bottoms up!"