You need a digital thermometer in the bottom of the box, but in lieu of that there has to be room for them to escape the heat lamp, to a cooler part of the brooder if they start getting too hot. They will gravitate to the heat if they are cold, but they have to have a cool down area if they are...
I had to take care of roosters when I was young, and our defense was to walk into the coop with a paper bag. If one came after us, we would just shake the bag and it would retreat. After a while, they just quit coming after my little brother and I.
