The phrase "small cages" refers to a confined space or enclosure that is not big enough for someone or something to move around comfortably. Full definition
They had lived for up to 6 years in small cages with wire mesh bottoms, no regular veterinary care, never stepping outside, and no caring human touch. (shelterme.tv)
Too many exotic pets are housed in small cages for many hours every day as owners are at work or at school. (avianexoticsvet.com)
Birds that were rescued from small cages can live here and fly around in freedom. (off-the-beaten-track.net)