Larsen traps take advantage of species’ territorial or inquisitive behaviour and are usually set during spring or early summer (the breeding season) when the instinct to carry out these behaviours is strongest. Live decoy animals may also be used to attract predatory birds to traps.

The bird used as the live decoy is usually a captured wild animal who experiences distress during confinement in the trap, including exposure to predators. Additionally, the capture of adult birds in the breeding and nesting season can cause distress and death of hatchlings and fledglings.