My broody hen hatch 8 babies about 4 weeks ago. Today she repeatedlt kept savagely attacking one of her chicks. They have all be in a run attached to my other ladies run. I removed mama and put her in with the other adults and it was like she never left. My question is however, tonight the chicks will be in their brooder box alone. They are mostly feathered but our summer nights have been cool lately (14°-15°C/57-59°F). Will they be okay without a heat source? They have been going outside with their mama since about 3 days old.