First Breeding Record of Crested Murrelet (Synthliboramphus wumizusume) on Baek-do Islands, Dadoheahaesang National Park, Korea

This study confirmed the presence of a new breeding site of the crested murrelet (Synthliboramphus wumizusume) on the uninhabited Baek-do Islands, Korea, which have been regarded as a potential breeding place. We visited the Baek-do Islands thrice from 2011 to 2012. During the visit in August 2011, we found some dead crested murrelets on Sangbaek-do Islet. During the visit in April 2012, we observed 23 individuals near Sangbaek-do and Habaek-do islets by using night spotlight survey and breeding nest survey. We also found 2 unsuccessful nests on the Geobuk-bawi Rock of Sangbaek-do islet, of which one was confirmed as that of a crested murrelet nest. Therefore, we conclude that crested murrelets breed on the Baek-do Islands. The carcasses and eggshells collected from the island during the surveys indicate that the Norway rat (Rattus norvegicus) is a major threat to the successful breeding of crested murrelets. We recommend that long-term monitoring and supplementary surveys are required to obtain a baseline understanding of the population trends of crested murrelets, as well as to identify potential threats and delineate mitigation methods.