Crows

The  are mutant birds found in all S.T.A.L.K.E.R. games.

"The only bird species to have survived in the Zone, enduring increased radiation levels and effectively avoiding anomalies. While the army pilots need to rely on complex detectors to avoid gravitational disturbances, the crow seems to rely on its own senses for that - a mystery that drives ornithologists and biologists mad. Various theories attempting to explain the phenomenon exist, all of them pointing to a highly specialized development of the bird's brain."

- encyclopedia description

Overview
The only bird species to have survived in the Zone, enduring increased radiation levels and effectively avoiding anomalies. While the army pilots need to rely on complex detectors to avoid gravitational disturbances, the crow seems to rely on its own senses for that - a mystery that drives ornithologists and biologists mad. Various theories attempting to explain the phenomenon exist, all of them pointing to a highly specialized development of the bird's brain.