I'm amazed at how chickadees and goldfinches can survive in brutally cold temperatures around here all winter. It gets down to -25ºF sometimes, but they're out there every morning hammering on the sunflower seeds.
And I'm truly amazed by the barn swallows who live on my property during the warm months. They will suddenly line up with all their fledged offspring on a phone line on some afternoon in mid-August, always before the 18th, and start chattering very excitedly. Then they disband as if nothing important has happened. The next morning, they swoop around as usual and scarf up some insects, line up again on that same phone line, sit in silence for a little while and then take off for Venezuela. No lunchboxes, backpacks, maps, they just split. They're outta here! And they're back every year on the dot of May 16th, flirting, mating, dive-bombing the cats in the driveway... generation after generation homing in on my old barn. It's humbling, really.