Chickens, as with people, all have different personalities. As you spend more time around them, you get to know each chicken for their individual personality. Certain hens can and will be dominant and push the others around, especially without the presence of a rooster. You seem to be focusing on the tail angle being an identifying trait of a roo. This may be the case between birds of the same breed, but not between different breeds of birds. Within a breed, roosters do have higher tails than females(or should anyway). But between breeds, tail angles vary on females, too. For example, my rhode island red has a tail angle of 10 degrees as per breed standard, while my ameraucana have tail angles of about 40 degrees as per breed standard. If your australorps have higher tail angles than the rest, the australorp breed standard may just call for a higher tail angle.