群体 is read as ぐんたい (guntai) and means colony.
ぐんたい
guntai
こたいぐん
population (e.g. of animals)
こたいぐんせいたいがく
population ecology
ぐん
group
むれ
むらがる
to swarm
むれる
to crowd
ぐんせい
all animate creation
ぐんしゅう
crowd
ぐんとう
island group
ぐんぞう
ぐんらく
many communities (villages)
ぐんじょう
ultramarine