Two Pigeons (Air) (Portugal 1971)

Stamp Two Pigeons (Air) it reflects the thematic directions:

Birds (Aves), a subgroup of Reptiles, are the last living examples of Dinosaurs. They are a group of endothermic vertebrates, characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight skeleton. Birds live worldwide and range in size from the 5 cm (2 in) bee hummingbird to the 2.75 m (9 ft) ostrich. They rank as the class of tetrapods with the most living species, at approximately ten thousand, with more than half of these being passerines, sometimes known as perching birds. Birds are the closest living relatives of crocodilians.

Columbidae (/kəˈlʌmbɪdiː/ kə-LUM-bih-dee) is a bird family consisting of doves and pigeons. It is the only family in the order Columbiformes. These are stout-bodied birds with short necks and short slender bills that in some species feature fleshy ceres. They primarily feed on plants, and can be taxonomically divided amongst granivores, that feed mostly on the ground on seeds, and frugivores, that feed mostly on fruits, from branches. The family occurs worldwide, often in close proximity with humans, but the greatest variety is in the Indomalayan and Australasian realms.

Environmental protection is the practice of protecting the natural environment by individuals, groups and governments.Its objectives are to conserve natural resources and the existing natural environment and, where it is possible, to repair damage and reverse trends.

Animals are multicellular, eukaryotic organisms of the kingdom Animalia (also called Metazoa). All animals are motile, meaning they can move spontaneously and independently, at some point in their lives. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their lives. All animals are heterotrophs: they must ingest other organisms or their products for sustenance.