Are alpacas intelligent?

Definitely.  They are alert, curious and quick to learn.  

Having been gently guided once from field A to field B, the next time they are let out of field A they will know exactly what to do.  They can be trained to a halter and are willing to be led.  

They communicate with each other by a variety of humming sounds, ear and tail movements and body postures.  You can greatly enhance your pleasure in working with these animals if you come to understand and copy the latter.