(CNN) -- Britons are being reminded of the species under threat on their own doorstep -- via their letter box.
The country's Royal Mail has issued a series of 10 stamps featuring mammals whose populations are declining in the UK -- from the humpback whale to the dormouse.
They are among 80 species of mammals that live in Britain and along its coastline.
The stamps' release coincides with the International Year of Biodiversity.
They are part of the Royal Mail's Action for Species series which highlights threatened flora and fauna.
The Royal Mail estimates there are around 2.5 million stamp enthusiasts in the UK and millions worldwide.