Sounds awful doesn't it ... and the thread makes it sound as if people were doing it just for fun
but a lot of these mass slaughters were done for serious study and a lot of our present knowledge is based on study of such specimens. At that time people hought nothing of killing any numbers of animals (that's what they were there for!

) any more than they'd think of pulling up thousands of plants ....
There are still people like that ("scientific whaling"?) but most people, in Europe at least, I think, would prefer less harsh ways of studying wildlife!