Egretta intermedia (Wagler, 1829) and Nycticorax nycticorax (Linnaeus, 1758) were found to have lived in the trees in the Arboretum for several years the number of which has now increased to 1 600, according to the observation by the Zoology Research Institute of the State Academy of Sciences.

Those birds originate from the southern areas and live in the marshland in the oriental areas.

Renowned ornithologist Pak Rae Bon said that it is a conspicuous phenomenon enriching the bird fauna of Korea that the birds which had lived in the southern sultry tract of wet land built their nests in the Arboretum of the Kumsusan Palace of the Sun.

Researchers of the Zoology Research Institute said that different kinds of birds flew to the area near the Palace on the picturesque bank of the River Taedong which has turned into thick woodland of various species of trees and all kinds of flowers.