Final answer:
The symbiotic relationship between a bird building a nest in a tree is neutral for the tree, but beneficial for the bird.
Step-by-step explanation:
The symbiotic relationship between a bird building a nest in a tree is neutral only for the tree. This is because the tree does not benefit nor suffer any harm from the bird building a nest in it. The bird, on the other hand, benefits from the protection and support provided by the tree for its nest.
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