Abstract
We observed a nest of the Black Paradise Flycatchers Terpsiphone atrocaudata attended by a female and two males in the forest of Nanatsumori, Shizukuishi Town, Iwate Prefecture on 9-11 July 2012. One male was a young adult, as indicated by short tail streamers, and the other was an adult with long tail streamers. Based on observation of aggressive behavior toward the male with long tail streamers, we assumed the younger male was the female's partner. It is not clear why the adult male with long tail streamers attended the breeding attempt. Further observation of the breeding behavior of this species with additional males is required, and DNA sampling would be helpful to identify the paternity in cases where two males were observed to care for the offspring in a nest.
