A rabbit. Specifically an albino rabbit, merrily hopping along on my neighbor's horta (micro-farm where greens and vegetables are cultivated, no direct English translation). Bunnies are not native to my neck of the woods (we have pacas and preás and capybaras, not rabbits), nobody that I knew of raised any, and this was in a zone near an urban natural reserve completely enveloped by urban zones on all sides.
Later I found out another neighbour, some weird toothless dude that talked too much and whose property is a dump of questionable legality, decided to just buy rabbits to raise as livestock. Doesn't seem like it went far, as they broke out and just roamed the neighborhood. I never saw the white bunny again, only a smaller brown one that also disappeared about a week later. Probably became food for the wild boas that haunt a creek close by.