I didn't know they weren't supposed to go outside. This is my first experience with chicks, hatched and raised by a hen. The chicks escaped from their enclosed area within their first week, and they were outside with the grownups in a flash. Since then (they're 4 weeks today) they've been outside every day, all day. They go inside at dusk, back to their little space, with the mom. There was one very unfortunate incident last week when I came home from work late, and found one poor little chick on the wrong side of the fence. It had gone through, and couldn't get back into the run. It was a bit traumatized for a few days but mom took good care of it, and it's fine now. They dash outside the minute I open the latch in the coop. I've reinforced the fence all around and I think they're pretty safe now. We've had some rainy, windy days lately, and they go inside if it gets too much. There's no heat lamp issue since they still sit with/under mom at night.