Intraspecific Intrusions into Nests of Spawning Longear Sunfish (Pisces: Centrarchidae)

Northern longear sunfish (Lepomis megalotis peltastes Cope) breed in colonies of closely-spaced nests, each defended by a mature male. Conspecifics often intrude briefly into a nest with a spawning pair and are driven away by the resident male. This disruptive intrusion behavior is performed by neighboring territorial males, smaller non-territorial males, and females. Intrusion rate and distance of intruding territorial males are independent of the presence of eggs in the intruder's nests. The main function of nest intrusion by females is eating eggs; by males it is apparently the fertilization of eggs in another male's nest. The possible selective value of male nest intrusion behavior is discussed.