I am reading the personal journals of John James Audubon, a gift from a friend, and I am struck by two things. Even though I knew Audubon shot the birds he drew so his drawings would be accurate, I did not realize how many birds he shot. Day and day out, his journals chronicle each one--fish hawks (ospreys), hermit thrush, 17 turkey, warblers, thrushes. Hardly a day goes by without killing 10-20 birds of as many species as he could find that day. The numbers are simply huge. Audubon also chronicles the contents of the birds' stomachs. So he's learning what the birds eat as well.
The second thing is that weather in 1820 seems quite a bit cooler than today. In mid-October of 1820, Audubon was on a boat on the river separating Ohio and Kentucky. He's already talking about heavy frosts--not one heavy frost, but cold weather day in and day out.
I remember October's weather as being more variable here when I was younger, but heavy and continual frosts probably didn't settle in until the end of the month or early November.
At any rate, a lot of things have changed in 186 years.