See how often they participate in the script: HERE.
Character Story: Monkeys are a pesky group of critters that live in the Faron Woods, slightly North of Ordon Village. The Ordonians first blame them for small annoyances around town, but they end up helping Link later.
Race Story:Animals appear all throughout Hyrule and are often often helpful in their own ways, either directly or through subtle advice. Link can talk to them when he is in his wolf form.