Destruction of eggs by the long-billed marsh wren (Telmatodytes palustris palustris)

The frequency of nest destruction by the long-billed marsh wren (Telmatodytes palustris palustris) and the stimuli eliciting it were examined by experimentally offering marsh wrens different nests with eggs or nestlings. Marsh wrens of both sexes, as well as juveniles, attacked any type of eggs in any type of nest, including those of conspecifics; they attacked them regardless of where the nests were placed. Nestlings of redwing blackbirds and marsh wrens were also attacked.It is suggested that nest destruction by marsh wrens has evolved as an interference mechanism to reduce possible interspecific competition. Through this behaviour marsh wrens most likely exclude redwing blackbirds and possibly some other marsh nesting species from certain parts of marsh nesting areas.