This is a souvenir sheet issued in 3 August 2007 for the 20th Asian International Stamp Exhibition. It was held at the Siam Paragon, Bangkok, Thailand from 3-12 August 2007.
The ducks featured on this sheet are the following:
Northern Pintail (Anas Acuta). Uncommon in wetlands from marshes to lakes. Males are unmistakable with long thin neck, brown head with white stripe up neck. Female ducks are surface-feeding and has greenish-brown speculum with white trailing edge, long slender neck and longer more pointed tail.
Common Shellduck (Tadorna tadorna). Numerous species of shell duck are widely distributed in temperate and tropical regions of the world. It is a large surface-feeding duck, sometimes known as a Sheldrake. Common shellducks are found in estuaries and fishponds
Northern Shoveler (Anas c/ypeata). All shovelers have a large, shovel-like bill. Uncommon in freshwater marshes and shallow lakes, in pairs or small groups often with other ducks. It has a distinctive large bill which gives a top heavy look and is best field mark for female. Females are also noted with brown belly and give a typical Mallard-like quack look. Males have white breast and chestnut flanks and belly. Males are silent when not breeding.
Greater Scaup (Aythya Marl/a). Usually found in brackish and saltwater bays and estuaries but also in freshwater lakes. It has rounded head and large and broad bill. White in wing extends well into primaries. Male has black front and rear, separated by grey back and white sides is indicative or diagnostic. Females are well-defined white face that differs from female tufted ducks.
I'm sharing this for Viridian's Sunday Stamps theme today, mini-sheets.