Problematic behavior in llamas
and misdirected territorial aggression
About territorial aggression
At maturity, male guanacoes (wild llamas) are instinctively driven to choose and defend a territory. The purpose of this drive is to provide a relatively safe, well-defended place for females to live and raise their young, and hopefully to provide the male with an opportunity to pass on his genes to the offspring of most or all of these females. This instinct is very strong, and it is present to some degree in every llama. It is as natural for a male llama to want to claim and defend territory as it is for a cat to catch and play with mice, or for a dog to chase things that move.
Some llamas are not very territorial; others are extremely so. The strength of this drive is definitively a genetically-transmitted (heritable) trait.
For domestic male llamas, territory is not confined to the area within the boundary made by the fence. It also includes everything within their range of clear vision. A territorial male will become agitated when another male or gelding is walked through an adjacent pasture — not because the animal "might" become a threat, but because the animal has already breached the bounds of that male's territory and thus constitutes a threat according to the male's instincts.