I noticed that my 20 week old white leghorn rooster will only mate with his 20 week old pullet. He won't try to mate the others who are 16 weeks old as of last Tuesday. Are they just too young and he knows it? Or will he try soon enough? I've noticed them squatting and staying close to him lately. Before they would run away from him all the time. Do the hens naturally want to be mated?