Howler monkeys may be among the most interesting animals to spot in Costa Rica. And they're not all that difficult to find — you just need to use your ears.
Drought, disease or something more sinister has caused a massive die-off of howler monkeys in Nicaragua, Costa Rica and other Latin American countries.
For male howler monkeys on the search for a mate, size matters; but being a well-endowed monkey comes at a price. The results of a new study show that in some species of howler monkeys the larger a monkey’s testicles are, the smaller its voice.
