noun
black-crowned night heron; night heron
A stocky heron species (Nycticorax nycticorax) active at night. The Japanese name is usually written in kana.
夕方になると、ゴイサギが川辺に現れる。
In the evening, black-crowned night herons appear by the riverside.
General term for herons and egrets; ゴイサギ is a specific species.
The name ゴイサギ is said to come from the bird's call, but the exact derivation is uncertain.