  In artificial systems, quantum superposition and entanglement typically decay
rapidly unless cryogenic temperatures are used. Could life have evolved to
exploit such delicate phenomena? Certain migratory birds have the ability to
sense very subtle variations in Earth's magnetic field. Here we apply quantum
information theory and the widely accepted "radical pair" model to analyze
recent experimental observations of the avian compass. We find that
superposition and entanglement are sustained in this living system for at least
tens of microseconds, exceeding the durations achieved in the best comparable
man-made molecular systems. This conclusion is starkly at variance with the
view that life is too "warm and wet" for such quantum phenomena to endure.
