The adaptive significance of multiple nest building by male marsh wrens

Abstract

Two hypotheses regarding the adaptive significance of multiple nest building by male marsh wrens, Cistothorus palustris, were tested: (1) female marsh wrens use the nests as a cue in selecting a mate, and (2) the nests serve as decoys to reduce predation on breeding nests. Data from both observational and experimental studies suggest that females do not use the number or density of nests or the proportion of time males spend building nests as a cue. Furthermore, no correlation exists between the total number or density of nests built and male pairing success. However, breeding nests found near large numbers of malebuilt nests were more successful than breeding nests near smaller groups of these nests. Our results are most consistent with the anti-predator hypothesis.