What are someways to tell if my femail rat is in heat it is so hard to tell with her

You don't need to be a scientist to learn if your rat is in heat, just watch her behavior for a month or two keeping in mind my answer to your question.

Female *pet* rats go into heat every 4 to 5 days from the age of 6 weeks up to around 18 months of age when her breeding days are basically over due to a drop in her estrogen level. Ethical breeders will not breed a doe after she is 1 year old. To do so is too hard on her old body and could lead to pregnancy and birthing complications

Her bottom does not swell up, but the vagina will appear more open. If she is bred a waxy plug will form in the vaginal opening preventing other males from mating with her. She only gets obscessed with building a nest about 3 days before giving birth. Female rats do not stay in heat and certainly will not die if they are not bred. This happens with ferrets but not rats.

Some rats are not very demonstative when they come into heat, but there are some clues that you may have seen but not associated with her being in heat.

In the Rat Fancy we affectionately call this, "the estrus dance".

While in heat the female will be receptive to the advances of the male rat. Unlike many other mammals red blood cells are not prominent, so there is no vaginal bleeding, rats do not have a period. When in heat the female rat will usually display by arching her back when touched http://www.ratbehavior.org/glossary.htm#... crouching as if frozen on the spot, vibrating her ears, and then running/hopping in short fast bursts. If there are other females in the cage they will mount the rat that is in heat.