First Record of Colonial Breeding of the Cattle Egret (Bubulcus ibis) in the Democratic People’s Republic of Korea

This study provides new information on the first colonial breeding of an alien species, the cattle egret (Bubulcus ibis) in Mangyongdae-dong, Mangyongdae district, Pyongyang, DPR Korea. Mangyongdae forest with a total vegetation area of 112 hectares has been used as a breeding habitat for ardeid species (black-crowned night-heron Nycticorax nycticorax, great egret Ardea modesta, intermediate egret Egretta intermedia, little egret Egretta garzetta, and grey heron Ardea cinerea) since the 1990s. In 2024, we first found the breeding population of cattle egret Bubulcus ibis in a subplot of the forest in Mangyongdae. Reproductive behavior was observed from mid-May to mid-September. Nests were found in 101 trees of 16 different species. The average height of nesting trees was 11.1 ± 2.9 m. The total number of active nests was 907 and the density of nests per tree was 8.98 nests tree–1. Mean clutch size was 2.89 ± 0.94 eggs per nest (n = 84), and the most common clutch size was three (50%). Mean hatch success was 2.77 ± 0.81 hatched eggs per nest (n = 52). This finding suggests a possibility of expansion of cattle egrets’ breeding area in the future in DPR Korea therefore a potential habitat management strategy should be developed.