Both males and females that are unfixed will display some pretty irritating, unwanted sexual behaviors. Both males and females will howl loudly, and trust me, that gets very old at 3 A.M. when you are trying to sleep. Intact males tend to spray, and the odor of the urine is overbearing and often times difficult, if not impossible, to remove from certain fabrics. Over the years, I have taken in several stray cats. I always get them fixed, but sometimes the week or longer wait for their appointments was challenging to say the least. One male ended up destroying a very expensive leather coat. Of course, it had been hanging up, but he clawed it and pulled it down and peed all over it. I ended up having to toss it. But marking is not only limited to intact males. Many unspayed females will also urinate to mark when they are in heat. Breeding is also ALWAYS a possibility. When a male or female can see, hear, or smell another cat, even a cat outdoors, they are far more likely to escape, as their drive to mate is very powerful, and they can become quite inventive and creative when it comes to finding ways to escape. Even if they find no way to escape, they can certainly cause a great deal of damage to your home trying to find a way. Certainly do not expect to have any blinds, screens, or curtains left untouched! It is always best to spay and neuter.