birds silhouettes over concentric circles with crane

>For other uses, see Bird (disambiguation). Many - see section below. Birds are bipedal, warm-blooded, egg-laying vertebrates characterized primarily by feathers, forelimbs modified as wings, and hollow bones. Birds range in size from the tiny hummingbirds to the huge Ostrich and Emu. Depending on taxonomic viewpoint, there are about 8,800–10,200 living bird species (plus about 120–130 that have become extinct in the span of human history) in the world, making them the most diverse class of terrestrial vertebrates. See more at Wikipedia.org...

mon usage, a collection is any group of items that has one or more properties in common, usually brought together for some specific purpose. See Collecting and Collectibles.The term can also be used more specifically:In mathematics, collection is not precisely defined, but can refer to various objects. Most often it refers to a set, class, family, or multiset.In museums and art galleries, the collection of objects in a particular field forms the core basis for the museum. In music, specifically diatonic set theory, a collection is similar to a tone row; see generated collection.In a church the collection is the money collected from the congregation during a service. The congregation normally place their donation into a collection plate or bag which is passed around and returned to the priest. Collection (Oxford Colleges) – college examinations in the University of Oxford. See more at Wikipedia.org...