The willow flycatcher and the least flycatcher are similar in appearance, and in many regions of the united states, their ranges overlap. the two organisms do not interbreed. based on this information, willow flycatchers and least flycatchers are

They are sympatric species. They occupy the same habitat but do not interbreed probably because they are reproductively isolated or practice behavioral isolation. To avoid extinction through interspecific competition, the two species probably practice resource partitioning (differences in how species use resources).