Alpacas are social herd animals that live in family groups, consisting of a territorial alpha male, females, and their young ones. Alpacas warn the herd about intruders by making sharp, noisy inhalations that sound like a high-pitched bray. The herd may attack smaller predators with their front feet, and can spit and kick. Their aggression towards members of the canid family (coyotes, foxes, dogs etc.) is exploited when alpacas are used as guard llamas for guarding sheep.
Alpacas can sometimes be aggressive, but they can also be very gentle, intelligent, and extremely observant. For the most part, alpacas are very quiet, but male alpacas are more energetic when they get involved in fighting with other alpacas. When they prey, they are cautious but also nervous when they feel any type of threat. They can feel threatened when a person or another alpaca comes up from behind them.
Alpacas set their own boundaries of "personal space" within their families and groups. They make a hierarchy in some sense, and each alpaca is aware of the dominant animals in each group. Body language is the key to their communication. It helps to maintain their order. One example of their body communication includes a pose named broadside, where their ears are pulled back and they stand sideways. This pose is used when male alpacas are defending their territory.
When they are young, they tend to follow larger objects and to sit near or under them. An example of this is a baby alpaca with its mother. This can also apply when an alpaca passes by an older alpaca.