Here's why:
* It refers to a group of individuals: A nest typically holds a group of eggs or young birds.
* The focus is on the group as a whole: We often talk about the nest as a single entity, rather than the individual eggs or chicks within it.
Examples:
* "The bird built a nest in the tree." (Focusing on the nest as a structure)
* "The nest was full of eggs." (Focusing on the group of eggs within the nest)
However, "nest" can also be used as a singular noun referring to the physical structure itself.
Example:
* "The bird sat on the nest." (Focusing on the nest as a physical object)
Therefore, whether "nest" is a collective noun depends on the context and the intended meaning.