These things are freakin cowards. They will run at the first sign of danger. Make sure to carry with argy while using for maximum efficiency. If you trained it for gathering prime, put it in a tame order group of your choice, and whistle attack target on the dead creature while carrying it with argy/quetz, preferably a quetz because you can carry and attack at the same time, and fly close. Then once it harvests, fly home and enjoy the prime!