What war caused the change in the bird?

The phrase "the change in the bird" is too vague without specific context. However, if you're referring to a significant change in a species or population of birds due to a war, one example could be World War II, which led to habitat destruction and alterations in ecosystems. Many bird populations were affected by changes in land use, pollution, and shifts in food availability caused by the war's aftermath. If you meant a specific event or metaphor, please provide more details for a precise response.