Answer: There is pollution in the east river
Explanation: If we think about it cant be a lack of food as it talks about having a large food source. Nor can it be climate change as that would result in a low yellow Perch population. it cant be they aren't able to catch the bird. So the only logical answer is a pollution that the birds are adapted to.
France gave up its territories in North America
The League of Nations didn't agree to decrease their armaments, but they decreased Germany's armaments
3,000 to 4,000 of them died from disease.
Hope its helpful !
