Wish to understand- why young cat chooses to poop at neighbor's place

[books mum]

I have 2 cats- 1 is 18 years old and the other is 1.5. Both are females.

Books, the younger cat, came with her stray mum and siblings at 2 months old.

At 5 months, I neutered mum and gave her and the siblings away to new families.

My older cat does not get along with Books, who is now very mischievous.

Books enjoys going out and the neighbors have complained that she poops in their flower pots and on the balcony upstairs (she gets in through the roof). I try to limit their outdoor times and I walk with them at night. I keep the windows closed to prevent her from going out all day but this gets uncomfortable for me when the weather is hot. 

I would like to understand the behavior - to prevent her from pooping at the neighbor's place.

There is an occasional cat who comes over, no one can really tell whose poop it is, but Books do sleep in the neighbor's boxes some afternoons.

There are 2 litter boxes with good quality sand at home and I clean the litter 3x weekly.

There are scratching posts and some toys at home. 

 

[yayi]

You need to scoop the litter boxes at least once a day, every day. Cats like their boxes clean. And since you said your 2 cats do not get along it is very likely they do not like sharing litter boxes. I recommend you get another litter box. 

 

[books mum]

I have 2 litter boxes in one bathroom allocated for the cats.

I can put one more out-  in a different place - and am wondering where other owners put the 'other' litterboxes.

 

[jennyr]

It is best to put the boxes wherever they are slightly out of the way, to give the privacy that most cats like. I have one behind a screen in the kitchen, one in the hall tucked beside a wardrobe, one under the stairs and two up on the landings, as well as in each bathroom. A total of 9 boxes and I would have more if I could think of places to put them. But then I have 11 cats!