Hey look I am a crow!! I can hold this pose for just a few breaths. This arm-balance almost kills my wrists. Takes lots of practice and strength to hold it for long. I usually practice arm balances towards the end of my yoga flow as by that time my body is warmed up.
“Strengthens arms and wrists. Stretches the upper back. Strengthens the abdominal muscles. Opens the groin. Tones the abdominal organs.” source PocketYoga