The 1st earthworm of the year

The warm air and the rain that came during the night had already the brought the earthworms out early this morning when I was walking to work.
This one on the wet sidewalk was indeed the 1st one I saw this year.

To commemorate this occasion, I will ask this perennial question one more time: Why do earthworms come out of the soil during and after rains?

They do so because they can come out without risking desiccation.

But because flat and wide and porous concrete surfaces were not in the original repertoire of earthworms habitats, evolution has not equipped earthworms with the ways and means necessary to deal with the rapidly dehydrating circumstances that arise once the rain stops and the sun comes out. As a result, the worms often get stranded on dry sidewalks and parking lots and die by the hundreds.