I am surprised none of you can solve this mystery.
Due to heavy watering trying to get all the growth possible on the 5th cutting of alfalfa, the field became heavily saturated and earthworms fled the field, frolicking in the dry road where about 100 crows picked them off with little effort.
It is commonly thought that earthworms flee because they sense drowning, but since they breathe through their skin, this has been discredited. I have heard several explanations but none explain why they only do it around here in the spring and fall. I think perhaps because our ground with the cooler weather doesn't dry as fast with the same amount of water used during the summer in the spring and fall, they surface and seek a drier but still moist soil.
Many of these worms crossed the road but found the soil much too dry due to no rain for weeks and only one light rain since late June. It was on their return trip moving much slower that many were eaten by the crows.
I am still undecided why they leave the irrigated fields and yards in the spring and fall if the overly saturated soil doesn't affect their breathing.
