Mutant Crow

Mutants Crows are small bird-like animals living on the surface and able to fly, found in Metro: Last Light.

Overview
Like small spiders and rats, mutant crows are harmless to Artyom, and simply serve the purpose of making the Metro feel more alive for the player. Mostly seen in the distance flying in large flocks, they can also be encountered when they land on the ground, most of the time when scavenging for food. Like other carcass-eating critters, they are quite often seen near dead bodies, flying away when the player comes to look for supplies on the human remnants.

Their overall appearance resemble ancient archosaurs, especially flying reptiles, since they do have long tails and membranous wings instead of bird-like wings covered with feathers. This would seem to mean that they are evolved from bats, which would also be supported by their propensity to gather into flocks, and by their overall behaviour. Their evolution from bats could mean that they are related to demons as well. However, the distinct crow-sound of the creatures would seem to refute this, as there is little evolutionary advantage for a species descended from bats to caw like crows. On the other hand, such appearance could also be explained by an evolutionary regression, led by multiple atavisms, making some primitive aspects (scaly skin, membranous wings and tail) in the animals. Since birds are heavily related to archosaurs, a bird origin may seem more believable.

Trivia

 * These can be easily observed in the swamp sections of Metro: Last Light as well as the levels with the Baby Dark One, such as Red Square, while fleeing away from the player.
 * Contrary to popular belief, Mutant Crows can be shot and killed.