I was wondering if this is true for other people who let their birds free range. I noticed after a rainstorm, that chickens are much more aggressive when they forage and forage for a very long time. On a normal, dry day, mine forage in spurts during the warmer times, with most happening in early morning and late evening. But no matter when it stops raining, they are all over the lawn and fields picking through the plants and eating greens. I guess the rain drives up worms? Though I haven't really seen them eat many worms at all, mostly greens.