According to Kim Kyong Jun, section chief of the Zoology Research Institute under the State Academy of Sciences, those birds lived in the area around the lower River Hapjang in the past, but now they are nesting in the wide forest zone along the middle and upper river, numbering at least 1 000.

They include Egreta garzetta, Egreta intermedia, Egreta alba, Nyticorax nyticorax and Bubulcus ibis.

The fact shows that the arboretum area has turned into a zone with ecological environment favorable for the inhabitation of animals.