Mods/Not So Simple Mobs/Biomes/Deciduous forest
This is simple biom with simple trees and plants on default. If you add NSSM mod you will change essentially the biom. NSSM adds plenty of creatures. Here also spawn ducks. Except them, here are masticones, mantises, larvas and other.
Types of Mobs
There are 4 types of mobs in deciduous forests. Masticone is boss here.