Answer:
Resource partitioning
Step-by-step explanation:
When two or more species have a requirement for the same limiting resources, competition exists between them. To reduce competition, members of these species develop certain strategies that allow them to coexist in the same habitat. It is called resource partitioning. It includes different timing and locations of feeding, different nesting sites, etc.
In the given example, different species of American warblers live on the same spruce trees but use the different areas of the tree canopy as nesting sites. These species also reproduce at different times to avoid competition. Therefore, it represents resource partitioning.