Pigeons, seagulls, starlings, and many other types of birds thrive in cities because there are few other wild animals that hunt them. In addition, they can nest in buildings, on window ledges, and on rooftops. Also, they get plenty to eat from our garbage—and when they don’t, people feed them.
In other words, humans have created a wonderful home for the birds. The result is bird overpopulation.
But bird overpopulation isn’t good for humans—and it’s not great for birds either. When a bird population becomes too large, the birds are forced to live in crowded nests. This makes it easy for them to pass diseases to each other.