On September 1st 1914, Martha, the last passenger pigeon in existence died. Three hundred years before, when the first settlers were arriving in North America, it was the most common bird in the continent, with up to 5 billion individuals. The story of the passenger pigeon is that of colonial destruction and contempt for the natural world writ large, and a reminder that for all the horrors taking place in Europe, mankind was already wreaking destruction of various kinds.
Here is an excellent episode of The Memory Palace on passenger pigeons
And here is a slightly less excellent video, for those who are inclined that way