The translation is wrong. "棲み着く" means "live (in a place) for a long time", so "テトラポットに棲み着いた猫たち" is simply "the cats that have been living in the テトラポット since a

The translation is wrong. "棲み着く" means "live (in a place) for a long time", so "テトラポットに棲み着いた猫たち" is simply "the cats that have been living in the テトラポット since a long time ago". There is no "arrived" about it.