Cat neuter/spay debate questions & musings

It has been said that it is bad to not have one’s domestic critters rendered nonreproductive. The reason usually given is that (let’s use cats as the example) if you don’t have your cat neutered or spayed and it has the opportunity to get out and about, you will have contributed to the birth of a litter of unwanted kittens a short time later. And that there’s already a burgeoning population of feral cats born in this fashion, and not enough food to go around for them, so the unwanted kittens to whose birth you would contribute through your negligence are most likely going to die of starvation.

I suppose there are ancillary reasons given for neutering and spaying: fewer yowling cats, fewer fighting cats, a lower incidence of cat-borne diseases (to whatever extent that’s a public health risk?), fewer cat-kills of birds chipmunks mousies and other critters that cats may prey upon (to whatever extent that’s a tragedy?), a lower incidence of cat-pee smells coming from the apartments of tomcat owners, etc… but those are seldom touted as reasons for why having one’s kitties fixed ought to be considered a moral imperative, yes?

MM-kay, clear me up on some stuff. Explain to me how the feral-cat situation is, or would be, different from the situation faced by any species of critter facing normal population pressures. Let’s say Norway rats. If there’s sufficient food supply, they reproduce and the baby rats survive rather than starve and, not being neutered or spayed, reproduce in turn, creating a Norway rat population explosion until equilibrium is achieved. And equilibrium is achieved when the food supply is insufficient to support continued population explosion, yes? Right? (It could also be achieved by other constraints, I suppose…diseases that kill rats, predators that are very successful at killing rats, etc, but if nothing else impedes population growth, food supply eventually will, yes?)

Now, we admittedly do not tend to like the Norway rat much. Decidedly uncute they are, and they bite, and carry diseases we’re susceptible to, and they make a mess of our pantries if they get in. So having the rat population limited by the rat starvation rate may only bother us to the extent that we’d rather it were limited by the rate by which we successfully poison them, whereas the prospect of zillions of starving baby kittens saddens us. But from the respective positions of the cats and the rats, is the situaton roughly identical? Am I incorrect in drawing this parallel due to something important I’ve missed?

The Norway Rat, of course, is considered to be able to survive on its own, without our protection and support (all too well, in many folks’ opinions), whereas some people would claim that the common domestic kitty cat is not equipped to do so. I’m not sure this is true, at least not in the sense that it’s probably true for great danes and quarter horses (and those feral cats are staying alive in large numbers even if they are also starving as kittens in large numbers), but let’s consider that. If true, it means the survival opportunities for the ferally born kitten are downright lousy, and the lifespan of the feral cat quite short, yes? If slightly less true, it means more kittens survive to reproduce until population pressures versus food supply reach equilibrium at a higher feral-kitty population than the equilibrium point would have been, yes? If only moderately true, yet more survivors, yet a higher kitty-population before equilibrium? If not true at all, yet more, but again equilibrium? So, aside from us feeling sadder about the poor ferally-born kitties who are so ill-equipped to face life without a human family to take care of them, are they actually facing something categorically different from the situation faced by other species, which vary according to how well-equipped they are to survive? (The bunny rabbit having a pretty definite edge on the California Condor there)

Or is there a mathematically different situation going if & when zillions of people, keeping zillions of kitty cats fed and healthy to the age of reproductive potential, and then letting them breed unchecked? Is it somehow the case that when we don’t neuter/spay our kitty cats, unwanted kittens die at a significantly higher percent of the total kitten birthrate than would be the case if they were a wild species whose population were limited by the food-supply equilibrium thingie? And if that’s the deal, can you hold my hand and walk me through the explanation until I get it?

Not sure where you want the debate to go. Reproduction is not the only reason to remove cat parts. Cats are very independent animals and their reproductive cycles magnify this attribute. Having taken in 2 strays I prefer them fixed. I also like them in pairs. They seem to work better as a team. I also wish I had one of them declawed but 10 years seems too long to make any changes.

I realize this will generate a lot of negative responses from people who dislike the idea of spaying/neutering animals but that’s life. I brought together a cat from the railroad tracks with a cat from the airport and those were my terms.

I’m certainly not going to pass judgment one way or the other. I’m more trying to explore the reasoning behind the sentiments.

Spaying and neutering has a number of health benefits, including lowering the incidence of certain rather common cancers in the animal.

But the biggest issue is this: My cats are my responsibility. I am responsible for their health, their happiness, their safety, and am also responsible for everything they do. Allowing them to reproduce only increases my responsibility. I don’t get to pass the buck. I don’t get to toss them out. I don’t get to shift the responsibility over to my neighbors or to the environment in general. The only way to live up to that responsibility is to limit the numbers I’m responsible for.

First, you refer to a myth of population growth: wild populations very rarely have food as a limiting factor on reproduction, and mass starvations are extremely rare in wild populations. Populations do not increase in a geometric progression; they increase in a sine wave (that is, when they’re far from their population limit, they increase slowly; when they’re medium-ways away, they increase quickly; and when they approach their population limit, their increase slows drastically). So starvation is not an issue in wild animals.

Following up on that, cats are different. when pet cats are well fed, they reproduce at a rate similar to that of wild animals with a stable population and a population limit far above their current numbers. If they’re then abandoned, they suddenly may have food as a population limit: first, they’re not accustomed to hunting for food, so the supply of available food is far less for them than you’d otherwise think; and second, even if they figure out how to hunt, there may not be enough rodents, birds, etc. in the area to supply their need (a need previously supplied by Meow Mix).

So that’s the first point: starvation may happen among the feral descendants of domestic cats where it would not happen among wild animals, because their artificial population increase exceeds the available food for them.

Secondly, they’re not a natural part of their ecosystem. Domestic cats that go feral can kill wildlife in numbers far greater than any other predator in the area, if they know how to hunt.

Thirdly, they can be nuisances or even threats, spreading disease that affects both humans and domesticated cats.

Fourthly, there’s a moral issue of resonsibility. Some people believe (I take no stand on this) that when we take pets, we take a moral responsibility for them greater than the responsibility we have for animals we don’t take as pets; similarly, we take responsibility for their offspring.


Left Hand of Dorkness

OK, this directly addresses what I was asking about. So it is mathematically different than it would be for a non-pet population!

Can you elaborate?

Hmm…I’m having trouble finding a good cite for population growth. This cite explains it a little bit.

But if you’re not looking for a citation, maybe an example would help.

(Imagine I’ve got a field that grows enough grass every yeard to support 100 rabbits. There’s also a hawk that watches the field, and has got a 1% chance each week of seeing each rabbit in a catchable position. The more rabbits there are, the better chance that hawk has of eating, and the more it’s going to hang out around that field looking for food.

When there are 6 rabbits or so, the hawk’s not going to be there very much. THe rabbits are going to breed like crazy, increasing the population quickly.

When there are 30 rabbits, the hawk will start hanging out around that field more often. The rabbits will increase their population more quickly.

As the rabbits get into the 80s or so, that hawk is going to hang out around that field all the time, eating the rabbits more often. Maybe the hawk breeds, so there’s a family of hawks hanging out there. Fewer female rabbits will become fertile, as the rabbit burrows become overcrowded. Some rabbits will leave the area, looking for another field. There’s not quite as much food for everyone: everyone has to work harder to get the nutrition they need (except the hawk, of course). Disease is likelier to strike within the crowded burrows. Population growth slows, and continues to slow the closer the population gets to 100.

With me so far?

Now imagine that there’s a rabbit farm nearby with 500 fat rabbits in it, rabbits accustomed to eating dry pellets, rabbits that weren’t taught as rabbitlettes which herbs were tasty and which ones were poisonous, rabbits that don’t know how to watch out for a hawk, and so forth. Some animal rights loonies come along and release all 500 rabbits into the field.

What happens to the population?

This is similar to what can happen when you have a wild, fairly stable ecosystem, and well-fed but poorly-trained predator species are released into it.


Ok, way back in College I took Population Biology. And, by what I leanred there, the OP has a point.

Let us assume an ecosystem of cats, dogs, and coyotes as predators; and birds, rodent-like mammals, and insects as prey. On occasion, the coyotes and the dogs will kill a cat, but generally that’s a fairly good picture. In fact, the housecat *in a way isn’t *even an “introduced species”- it’s just assuming the niche of the bobcat and other small wildcats. Man(especially ranchers) has been vigilant at destroying predators, even though it is rather unlikely that a bobcat would attack a steer. :dubious: :rolleyes:

As the prey population is eaten, the predator poplation goes with it downhill, until the predator pressure lessens enough so that the prey increases- bringing the predators back up with it. In a very simple ecosystem, the graphed waves are lovely, the highs chasing each other across the track. In other words, the predator population *is *self-correcting.

But enters a problem. People feed feral cats and of course they feed their own “outside cats” (let’s not get started on that :stuck_out_tongue: ). Thus, the cat population never “hits bottom” and can stay artifically high, keeping up pressure on the prey, so that the prey pop is never allowed to rebound. In “outdoor” cats, the cat often doesn’t even eat it’s prey- Puss “brings it home as a trophy”. In feral cats- the cats are usually fed just enough so that they don’t starve, but they are still hungry- thus they hunt. Thus, cats can hunt the local wildlife to nigh extinction. In some areas with a lot of cats, you almost never hear birdsong. :frowning:

So- because of “human interferance” in “keeping the preadators fed”- the OP is quite wrong. We *do *need to spay & neuter the cat population.

  • I am going to lump the Lagomorph (rabbits and hares), the Opossum, and small insectivores into “rodent like mammals”- just for this post.

Does this apply mostly to prey species, or predators as well? I can see how other factors would slow the increase as a prey species approaches its carrying limit, but is it the same with predators?

Being curious rather than argumentative.


That’s a good question (I’m reinterpreting “prey species” as “herbivores or producers,” if that’s all right, since many predator species are also prey species). If I recall correctly, in most complex ecosystems, populations tend toward homeostasis: they fluctuate slightly about a fairly stable level. Models of rabbits-and-wolves show rabbit populations surging, followed by wolf populations, at which point rabbit populations plummet, followed by wolf populations; but real-world systems are more complex than that, as the wolves will find things to eat besides rabbits, and things besides wolves will eat rabbits.

But it’s been awhile since I studied this; and I know of at least one population dynamic that goes in surges. Prickly pear cactus in Australia was a completely out-of-control exotic species, until a specific type of moth was introduced. This moth had a wide range, a very fast reproduction rate, and a very specific diet, inasmuch as it only ate prickly pear cactus. The moth quickly swarmed across Australia, devastating the prickly pear population and driving the cactus to the brink of extinction. But then the moth died off. The moth stays in very low population levels until the cactus population reaches sufficient density, at which point the moth population explodes, eats most of the prickly pear, and dies off again.

It’s worth noting that neither species is native to Australia, and this dynamic has only been in place for less than a century; over time, other creatures will probably learn to eat the prickly pear, and the moth might mutate to eat other things, and both species are likely to reach a less dynamic population level.

But your point is valid; take what I say with a grain of salt when it comes to carnivores, as my memory of the population dynamic is far from perfect, and I’m having trouble digging up easy-to-read cites on the subject.



Thanks for the response.

The only case I ever studied in anything like depth was some island (Isle Royale?) in Canada. There I believe the moose population experienced the sort of boom-and-crash oscillations described above.

Interestingly, it was after the introduction of a prey species (I think wolves, although I didn’t think wolves would prey on moose if there was something easier around) that the moose population stabilized. The wolves were apparently eating enough moose calves to keep the population under control. So this meant that the moose population never exceeded the carrying capacity of the island, so they didn’t starve.

I’m not sure if the population of wolves was limited by the availability of moose calves to eat - it may have been at least partly by adult wolves being killed by moose in the course of hunting.

I imagine the populations of newly released cats would be limited by incompetent hunting and therefore starvation - plus cars. I heard someone describe automobiles as a prey species on white-tail deer, because cars kill more deer than hunters. But I think the elimination of predator species has allowed the deer population in many areas to reach the limits imposed by food supply.


A major problem with feral cats is that in residential neighborhoods people don’t much like that the whole world is their litter box. We have such a problem on our street, and the family across the street is pretty steamed about not being able to let their children play in their own yard without checking it out for stuff they’d rather not have the little ones put in their mouth, or track into the house.

Estimating conservatively, one mature queen can have as many as 3 litters per year. Each litter may have upwards of three kittens. The offspring become fertile after about 6 months. You do the math. That leads to a LOT of cats. There are no natural predators, since we have eliminated foxes and the like from our suburban neighborhoods. I love cats, but feral ones live short and miserable lives, filled with injury and disease.

Coyotes will take cats in a lot of places where people don’t even know they have coyotes.

I believe you, but am pretty darn sure there are no coyotes here in central NJ. Actually, if there were, that would seem to me to be all the more reason to keep my cats indoors AND spayed/neutered. Dying by being torn to pieces by a coyote does not seem like a nice way to go.

It looks as thought NJ has a coyote hunting season, which might mean that they’ve reached nuisance levels. I don’t know enough about predator hunting to say what it means about population levels, if anything.

And absolutely, it would be a terrible thing to expose pets to death by dismemberment. To me, that’s the antithesis of responsibility.

I tend to assume we have coyotes here in Manhattan, if not necessarily in overwhelming quantities. That is one seriously successful expansionist species. I dunno about Hawaii but I suspect they’ve got a solid toehold in the other 49 at least. Don’t know about Europe, may have more fox/wolf competitors there. In the US, the fox and wolf were substantially suppressed and the less-suppressible coyote quicly took over.

Generically, thanks for the education. I got what I’d asked for, and I understand much more than I did before.

Interesting! It does make me wonder whether this was an introduction of a predator species, or a re-introduction of a predator species. From my limited understandings, populations that oscillate wildly tend, at some point, to stabilize either at 0 or at a happy medium: if they continue oscillating over several centuries, at some point their population dips beneath a level from which they can’t recover, or else the environment changes in some way that leads to less oscillation.

I wonder whether wolves were killed off on that island, leading to oscillation, and then re-introduced, bringing some stability back into the system.