Now extinct, the passenger pigeon was the most numerous bird on earth in the nineteenth century. Audubon described a hunt for it in Kentucky in 1831:

The pigeons, arriving by thousands, alighted everywhere, one above another, until solid masses as large as hogsheads were formed on the branches all round. Here and there the perches gave way under the weight with a crash, and falling to the ground, destroyed hundreds of the birds beneath . . .

Ford has portrayed the birds as causing their own extinction by bad behavior including gluttony, envy, and murder.  link