Answer:
Forest.
Explanation:
Berries and nuts are typically fruits and products of trees, and there must be plentiful amount in which to have a population (though it states only an organism, but it can be assumed). Brown fur is typically camo against a brownish background, which can be reflected essentially through bark & wood of trees.
*Most likely the given organism is a squirrel, which typically prefer forest or habitats with trees or tree-like objects.
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