There was a warning sign for Brazil’s current yellow fever epidemic. That red flag could be found in the Amazon rainforest, where primates were dropping like flies.
Capuchins, marmosets and howler monkeys either came down with yellow fever or saw their numbers shrink.
The most alarming of these deaths: howler monkeys.
These primates earn that name. Howlers are the loudest of all monkeys, with a wail that can be heard miles away. The monkeys use their howl to warn other primates that they own an area. The whole species joins in this yell, usually doing so every day at dawn and dusk.
But, what happens when howler monkeys don’t make that noise?