Agh, a similar thing happened to me earlier this summer, Zoealea.
I was on the way to the bus stop so I could get to school and passed under a tree, and I noticed a baby bird on the sidewalk. It was moving a little bit, too, but since I was in a hurry to catch my bus I had to leave it behind and spent the next hour or so trying to get in touch with friends who lived near me to try and save it. I don't know what happened to it.
Thinking about it still makes me feel like the worst human ever. I left behind a poor little baby