Territorial defense and lek behavior of the black swallowtail butterfly, Papilio polyxenes

Summary

• 1. The mating system of the black swallowtail butterfly, Papilio polyxenes, was studied near Brooktondale, Tompkins County, New York, USA. Butterflies were marked individually during 8 broods from 1972 through 1976.

• 2. Males perched within restricted areas of approximately 75 m² and aggressively chased conspecific males that approached the area. These areas constitute territories since males maintained exclusive use of the areas 95% of the time through these encounters.

• 3. Males defended areas of high relative elevation and topographic distinctness, but did not defend resources such as sites for oviposition, feeding, or roosting.

• 4. Success in defending a territory depended on the number of competitors and the male's previous success but not on the size of the male. Males that emerged early in the brood were more likely to defend a preferred territory.

• 5. The clumped distribution of territories produced lek-like male assembly areas. Females released at a distance flew to these areas and circled until they encountered a male.

• 6. The most desirable territory, as measured by frequency of occupancy or male-male encounter rate, had the highest female visitation rate. Territorial defense reduced interference from conspecific males during courtship. Nearly 80% of the successful courtship flights were confined to a male's territory or nearby undefended areas.