New research has found that monkeys increase their use of scent markings to compensate for human noise pollution. The study, led by researchers from Universidade Federal do Amazonas in Manaus, Brazil, and Anglia Ruskin University in Cambridge, England, is the first to investigate how primates change their communication strategies in response to noise pollution. The researchers studied endangered pied tamarins (Saguinus bicolor), which use both vocal calls and scent markings. The researchers found that the frequency of scent marking directly increased in line with noise decibel levels.