My cat is acting weird. She’s standing on her rear toes with her butt in the air. What does it mean?

The exact words of the cat's owner asking for help on Reddit.com are as follows:

My cat has been acting weird. All day she’s been standing on her rear toes with her butt in the air always pointing it at me. She’s never done this before what does it mean?

I shortened them for the title. The picture accompanying the words immediately tell us what is going on.

My cat is acting weird. She’s standing on her rear toes with her butt in the air. What does it mean?. Female (queen) in heat prepared to mate. Image: u/OMGJay on Reddit.

Their female cat is in oestrus (heat) and is seeking a mate and ready to copulate. She raises her bottom slightly and places her tail to one side. The classic pose of a female cat waiting to be mated. Before doing this, she would have provided other signals to males to indicate that she was ready to mate such as rolling around flirtatiously.

Clearly, the owner has adopted this cat and unusually not had her spayed (sterilised). He/she may have rescued her informally (found her). The vast majority of people in the West i.e. Europe and America, spay and neuter their female and male cats. 

If there is a lesson here it is to check if an informally adopted female cat has been spayed. It can hard to find the scare from the operation. You might like to ask a vet.

The veterinarians say that female cats are happier when they been spayed and it helps to remove the possibility of certain diseases affecting female cats. So, it is highly recommended.

The spraying operation is more severe than the neutering operation for male cats but I argue that male cats' appearance changes when they are neutered. They become more feminised whereas for female cats there is no change in appearance. I prefer the non-neutered male cat appearance.

In the spraying surgery, the uterus, fallopian tubes and ovaries are removed. The operation prevents the queen (unsterilized female cat) from coming into oestrus and eliminates the problems of cystic ovaries, neutering infections, false pregnancies, irregular heat cycles and confinement during the mating season. 

And it also reduces the frequency of breast tumours. Spaying reduces the chances of a female cat developing mammary tumours by 90%.

Spaying does not make a cat fat and lazy. It might slow their metabolism and this can be countered by a fresh diet and some more exercise.

The best time to spay a female is at 5-7 months of age before she goes into her first heat.

Veterinarians believe that a spayed female makes an outstanding pet and she is able to devote herself exclusively to her human family. 

Plus, you don't have the risk of acquiring a bunch of kittens to care for and find homes for.