My 9 chicks are 5 weeks old and have been in our coop since they were two weeks old. They have a heat lamp at night to make sure the temp is right. It's been around 100 degrees here and it's hot in the coop, so I've been letting them out into the run (about 50 feet per side) under a huge tree for shade. But when it gets dark, they don't go back into their house and I don't know why. Are they too young yet? I've had chickens before and they always "put themselves to bed at dusk". I hate to not let them out because of the heat, but it's a real struggle rounding them up at night. Any ideas?