A cat’s natural territory size is quite large. Some studies (on unowned cats) show they can travel over 10km a day patrolling their territory. Owned cats travel less, but still much more than we think (if they are allowed outdoors).
In a cat’s natural environment, territories often overlap. Solitary cats seem to manage this using a system of ‘traffic lights’ to time-share the territories. Scent marking allows the cats to learn information about each other, like gender, age and health status. Importantly, they can also determine the timing of the scent marking so they can happily share the territory without confrontation (i.e. they will try to avoid being in a certain place at a certain time if they know another cat goes there).
Though, when it comes to sharing, all bets are off if the territory is particularly devoid of important resources. When food, for example, is scarce, cats will defend their patch, aiming to scare off the competition.
Makes sense, right?
Now, imagine when a cat who is evolutionarily-designed for a very large outdoor environment is squeezed into a space the size of a postage stamp (relative to the outdoor territory size). This is effectively what we are doing with indoor cats. Don’t get me wrong, I’m a fan of keeping cats indoors for many reasons, but it needs to be done with thought.
On top of this, we often have more than one cat! So, multiple cats in a very small territory size. Cats who are naturally solitary for the most part (it does appear that domestic cats may have a few genetic adaptations that can make them more sociable), now have to share a small territory with others, because that’s what we want.
This is why it’s incredibly important to create an ‘environment of plenty’ in your home. In order for the cats to be happy in a smaller environment, it needs to be extremely resource-rich. If a cat feels in competition with another for important resources, it’s unlikely he’ll be 100% happy in that environment.
‘You need to create an environment of plenty’ is a pretty broad statement. What exactly do I need to increase? How many of them do I need?
This is where the ‘n+1’ rule comes in. Well, it’s more of a guideline that a rule. Most of us have heard this rule when it comes to litter boxes.
‘N’ = the number of cats.
So, when it comes to litter boxes, for example, the number you need is the number of cats, plus one. If you have 2 cats, you should have 3 litter boxes, 1 cat should have 2 litter boxes, and so on.
I like to extend this rule to some other important resources as well.
Which resources are they?
Mainly what I call the ‘4 King Resources’:
• Cat trees/elevated space
Every household should ideally aim for n+1 of these at a minimum.
Of course, there are more resource types, like toys, scratching posts, cat wheels, safe outdoor spaces/enclosures etc, but the n+1 rule doesn’t necessarily need to apply to these.
Let’s now go through each of the King Resources so we can make sure we are creating that all-important ‘environment of plenty’.
Food is the ultimate resource. If a cat feels in competition for food, it’s certain to cause a level of territorial stress.
If you primarily meal-feed your cats, this isn’t too much of an issue, and the rule doesn’t apply (because food isn’t left out). As long as you are feeding enough calories, enough meals each day (on time), and that the cats are fed separately (ideally out of sight) of each other, things should be ok.
However, free-feeding is different story.
If you have more than one cat, and you have only one food bowl, it’s going to cause problems.
It doesn’t matter how big the bowl is, how much food is in it, or how much you have left in the cupboard, one food location creates unnecessary scarcity. A cat will simply see only one place that has food, and this can result in what we call ‘resource-guarding’, where a cat may hang around the food bowl at times to stop others from accessing it.
We can fix this, and create a perceived abundance of food, by having multiple food bowls around the territory. This will help the cats feel there’s enough to share, and more anxious cats won’t have to ‘run the gauntlet’ past the others to eat.
So, using the ‘n+1’ rule, if you have 2 cats (for example), you should have a minimum of 3 food bowl locations, scattered around the house.
When deciding on food bowl locations, don’t make the rookie-error of only considering the floor space. Cats are masters of their vertical territory, so you could have food bowls off the ground on bookshelves, TV cabinets etc. In fact, they’d probably prefer it!
One thing to make sure, is that you don’t place food near water or litter.
Cats seem to have developed an evolutionary safety mechanism where they prefer food to be away from a water source or litter source (potential contamination risk). I’ve seen (some) cats that will avoid a water source if it’s too near the food, or avoid a litter box near the food, and so on. Many cats will tolerate it, but ‘tolerate’ is the key word here. They’d probably much prefer them separate.
Water is the next most important resource.
Only having 1 water source amongst several cats, no matter how large, is likely to cause territorial stress.
Like the food, apply the ‘n+1’ rule and scatter these around the territory.
Interestingly, cats seem to prefer running/flowing water sources. There are a few theories for this:
• It’s more likely to be fresh, whereas still-water could be stagnant/contaminated
• They can hear it, drawing them to the location
• They can see it. Cats don’t have great eyesight, and running water may allow them to see the surface of the water better. Some say that this is why cats will put their paw in and splash a still-water source!
In many of my consultations, if I notice that someone is only using still-water, I suggest buying a cat drinking fountain. They often tell me later that it’s a huge hit and they love drinking out of it now! This can be more important if you feed primarily dr y-food, as cats won’t often make up the balance of their moisture needs, so any encouragement to drink is a good thing.
One issue with fountains, is that if the power goes out or it stops working, the water may be inaccessible. For this reason, I always suggest having a still-water source available as well.
Lastly, as you might have guessed, keep the water sources away from food or litter.
Most of you already understand the ‘n+1’ rule when it comes to litter boxes.
If you’ve read anything I write on the subject, you’ll know that it refers to the number of litter box locations, not litter boxes themselves. So, if you have 2 cats, you need 3 litter box locations.
A lot of people I see will put all the litter boxes together in one place, thinking they’ve applied the rule. To a cat, this is only seen as one big litter box, and can cause the dreaded resource-guarding we are trying to avoid.
Lastly, keep them away from food or water.
Side note: as you’ve seen, when it comes to food, water and litter, they all need to be separate. This means that if you have 2 cats, you’ll need 3 of each, all in separate locations (yes, this means 9 locations!). Remember this is only a guideline, so just do the best you can. Some people may not have the space to do this, but any improvement is still good (e.g. 2 litter box locations is still better than 1).
Given that cats evolved in the middle of the food chain, they gain confidence, comfort and safety from being up high. A house devoid of climbing opportunities will be somewhat stressful for a cat.
Vertical space can take many forms, from cat trees and shelves, to counters and human furniture. I believe it’s important for the cats to have a sense of ownership, so whilst they might share the couch or bed with you, they should still have some cat-specific furniture (cat trees).
Ideally vertical space should be quite high (e.g. chest, head height). I often see owners that tell me they have cat trees but when they show them to me, they’ll be quite small, around their waist-height. Many cats like to be as high as us!
Try to apply the ‘n+1’ rule here, but if you can’t, just do the best you can. They do take up a bit of floor space and can be expensive.
As far as locations, consider socially significant areas (where you spend a lot of your time) and the sub-territories (more on that next).
A quick note on scratching posts: they are very important, and should probably have their own category. Though large cat trees often serve double duty as a big, sturdy scratching post. If your vertical space mostly consists of shelves or other furniture (i.e. not cat trees), you’ll need to add standalone scratching posts using the ‘n+1’ rule, lest you find your furniture becomes victim.
Up until now, I’ve simply said that the resources should be spread around the territory (and away from each other in the case of food, water and litter box locations).
If you observe your cats (especially if you have a large house), you might start to notice that they individually like to spend more time in some areas than others. I mean, there will be large overlap and common areas considering a house is quite small comparative to their normal territory, but you might find that one cat likes spending more time in one part of the house that the others, for example.
These are sub-territories. When allocating resources around the house, try to consider these areas and make sure there’s at least one of each resource in them. That way, an anxious cat doesn’t need to run the gauntlet past more confident cats for the important resources.
What about the other resources, like toys, food puzzles, cat grass etc?
The more the better! The natural outdoor environment has almost unlimited enrichment for a cat. The indoors can actually cause stress due to boredom. When it comes to resources, more is always better.
Just remember to try and create some novelty when it comes to toys and food puzzles so that they don’t get bored. If possible, rotate the set of toys each couple of days to maintain their interest.
I see potential causes of territorial stress in many houses I see during consultations. If you get these basics right, especially with the main resources at least, you’ll go very far in reducing this stress as much as possible.
Remember that the ‘n+1’ rule is just a guideline. There’s no magic event that happens when you have exactly n+1 of each resource – some cats require more and others can happily tolerate less. It’s just a handy reference tool I use when assessing environments and seems to hit the mark more often than not.
Thanks for reading!
Here’s to happy and healthy cats.