 When an intruder interrupts a female's courtship behavior, the female would rapidly and aggressively chase the intruder away if the intruder is of the same sex.However, when the secondary male, or the intruder male approaches, he, instead of the female, exhibits trembling behavior, and also helps to defend the female and primary male's isolated territory.If the primary male does not respond to female's trembling, the female leaves periodically to visit the secondary male and displays trembling behavior which often results in mating.