Hi! I find it depends entirely on where you live and the style of cage. I have 3 hedgehogs. My girls are in a double critter nation that has insulation around it to help keep warmth in. They do just fine with one CHE each. My boy lives in a large wire cage set up. He has two CHEs and a blanket on the front of his cage in colder months to keep warmth in. I live in New England though where it gets very cold at night. I found the best way to determine what each of them needs it to set the cage up a few days prior to their arrival and monitor the cage temps. Then you can alter things as needed without putting your baby in danger of getting too cold.