In São Paulo, Brazil’s largest city, it is easier to find giant jararaca pit vipers (Bothrops jararaca) in a small fragment of Atlantic Rainforest surrounded by urban sprawl than in a nature reserve that is 16 times larger, even though more food is available for snakes in the latter. A new study suggests that the difference may be due to the number of predators in each habitat and not to the availability of food, as the researchers supposed at the outset.