The howling monkeys (Alouatta palliata) that inhabit the northeastern subtropical forest of Argentina play an important role in the regeneration of the jungle as they move back and forth across the Paraná River, says a new study by the University of Buenos Aires school of natural science. The population of this species remains homogeneous without being isolated. Because these monkeys feed on seeds, their excrement contributes to the maintenance of plant populations on both sides of the Paraná.

Unlike the Amazon river, which constitutes a barrier between species on each bank, the Paraná “acts as a canal of species maintenance” and aids in the reproduction of jungle plant varieties, says professor Marta Mudry.