I've killed a couple baby birds by accidently leaving the heating pad on too high. I also left my two guinie pigs outside and they both got heat stroke. I left them in the shade, but forgot that the sun actually moves, taking the shade with it, oops .
This is my husbands story, but I think it's kinds funny. When he was a young boy he saved a duckling that was trapped in the canal. The ducklings family had already been sucked under the water and this baby was trapped in the whirl pool. So he brought it home and kept it in the backyard. One day he goes in to check on the duckling but doesn't see it anywhere, so he takes a step back to leave and steps right on the poor duckling. Worried that everyone will find out what he did he throws the duckling in the street and runs away. He comes back later to the horrible news that his duckling got out of the backyard and got hit by a car. He bursts into tears but never tells anyone the truth. Fastforward about ten years when I meet my husband and hear this story for the first time from his mom, who thinks it is so cute that her little boy has such a kind heart. Embarressed by the story, my husband blurts out " I wasn't crying because the duck got ran over. I was crying because the stupid thing got under my feet and I stepped on it." This was the look on his moms face