My chicks are six weeks old. I keep them in the brooder (a large rabbit cage) in the garage at night and on rainy days, let them outside in a small fenced and securely netted area of the yard in the day. (We have a family of hawks in our area, and they are constantly circling above our yard.) So far I've kept the light (which is also a source of heat) on all night and whenever they are in the brooder. When should I start them on a day/night routine? Are they old enough not to get cold at night? There are six chicks: two silkies, a bantam cochin, a speckled sussex, an Americauna, and a Wyandotte.