Territory switching behavior in a sedentary tropical passerine, the dusky antbird (Cercomacra tyrannina)

Demographic data from an 8-year study of a marked populationshowed that switching territories and mates is common in bothgenders of dusky antbirds (Cercomacra tyrannina), a sedentaryneotropical passerine with year-round territories and pairbonds.We conducted 22 experimental removals and followed six naturaldisappearances to examine territory switching. Antbirds quicklyabandoned territories and mates to move to openings createdby experimental removals. Pairing with the resident on a newterritory was rapid. Unmated birds attracted new mates by singinga gender-specific song that differed from songs given by matedbirds. There were no gender differences in replacement timeor rate. Some vacancies, experimental and natural, were notfilled, suggesting that floaters were rare. Territory and mateswitching were not related to immediate enhancement of reproductivesuccess because the probability of reproducing successfullywas equally poor on all territories. Territory switching maybe an overlooked but common tropical form of territorialitythat increases individual survivorship during periods of lowfood abundance (dry season). We suggest that switching is favoredwhen low annual reproductive success enhances selection fora long lifespan as the primary means to increase reproductivesuccess.