From what I have heard, the llama/alpaca/guanaco type animals can be very possessive and strangers trespassing on their territory can find themselves stomped on, shoulder charged and spat at.

They might look sweet and fluffy, particularly the babies, but watch out for mom and dad. Sheep tend to bring out protective behavior in llamas - perhaps because of their size.

Offending dogs tend to get knelt on and crushed to death.

Alpacas might not need protection from rustlers - possibly the reverse - I have this picture of a couple of pairs of frightened eyes gazing down from a tree as it is shaken by angry Alpacas, whilst in the background there is an overturned Landrover and trailer.