Not a great photograph, but I'm always thrilled to see a bald eagle (this one from Newfoundland last summer.) They were on the brink of extinction due to hunting and the effects of pesticides on their eggs -- at one point there were only 400 nesting pairs in the United States -- but after DDT was banned in the 1970's they rebounded.
So each one I see feels like a little miracle: things can get better, you can come back from the brink of disaster.
It's unnerving how silent millions of people can be. I hear birds, wind rustling in the trees, the occasional siren. Otherwise, nothing.