Song bird stamps released  by USPS.

The new Songbirds stamps, released on April 5, depict 10 artistically crafted images of popular songbirds from across the land. To accompany the release of these vocally gifted birds, audio samples of their melodic musings are available for the listening pleasure of all. Between 4,000 and 4,500 different types of songbirds can be found around the planet, accounting for nearly half of all bird species. Songbirds are identified by their highly developed vocal organs. Some songbirds, like the crow, have harsh voices, others sing rarely or not at all. All songbirds are classified as perching birds. With three toes pointing forward and one pointing backwards, they can grip branches and grasses with ease.  The new Songbirds stamps are available as First-Class Forever stamps in books of 20 and can be ordered here.