1. Mallard x American Black Duck hybrid Anas platyrhynchos x A. rubripes, male, Montgomery County, Maryland, USA, January 2, 2005. Note the mixture of field marks - the overall Black Duck-like body and contrastingly paler head, but with green stripe over the top of the head, narrow white borders to the blue and black speculum and decidedly bright yellow bill. Below is an image of an American Black Duck that was also present, for comparison. Sony DCR-PC330 MiniDV Handycam; still capture; 37mm; 1/90, f4.

2. American Black Duck A. rubripes, male, Montgomery County, Maryland, USA, January 2, 2005. Note the drab olive-colored bill, lack of green on the head and lack of white borders to the speculum. Sony DCR-PC330 MiniDV Handycam; still capture; 37mm; 1/100, f4.