noun
Specifically Tachybaptus ruficollis, a small waterbird common in Japan.
池でカイツブリが泳いでいる。
A little grebe is swimming in the pond.
noun
grebe (any species)
General term for any bird in the family Podicipedidae.
カイツブリ科の鳥は潜水が得意だ。
Birds of the grebe family are good at diving.