Will birds eat just after a rainstorm
Yes they eat after rainstorm; they feed on worms since worms come out from the soil when it rains and they can't breathe. They mostly feed on the caterpillars and the earthworms.
100% because the worms like to come out of the soil and the bugs to enjoy the freshness of the earth, so its one of the best feeding times for birds.
Why wouldn't they
Yes. That's actually why birds hop too. They "simulate" rain for the worms.