You should read the Audubon Society's page on the demise of the passenger pigeon. It went beyond hunting. They used poison, fire, whatever they could use to eradicate the bird. When I started asking some old guys born in the 1930s and 1940s who knew even older farmers who were around when the pigeon was around why this had happened he said the birds were known to drop into a farmer's field and eat everything overnight, bankrupting farmers. The passenger pigeons were locusts to them. They had every intent of eradicating them. It wasn't a mistake.