I have 4 week old pullets in the brooder. One of them is very adventurous and fearless and gets itself into all kind of mischief. When I brought them home 2 weeks ago they all slept huddled up. Now, she is sleeping away from the other 3. It is almost like she is watching over them. They are all RIR. They are all about the same age and from the same hatchery. What kind of chicken behavior does this fall under? Thanks!