Feeding the Feral: A Study on Feral Cat’s Environmental Impact.

Cat with mouse

Feral Cats on the prowl, an all to frequent sight while documenting urban wildlife. Some cast aside by their human owners, others born wild on the city streets, creeks, and open spaces. We decided to take a look at just two out of many 100s of feral cat colonies in wildlife designated areas of the Santa Clara Valley and examine the cat’s possible environmental impacts. By observing these cats we know that many species of wildlife fall prey to feral cats: Insects, rodents, reptiles, amphibians, and birds are impacted. All ground dwelling wildlife has to keep a keen eye about them when in the territory of a feral cat. These two colonies are in wildlife areas that are also habitat to many threatened and endangered species of wildlife like the Salt Marsh Harvest Mouse, Tiger Salamander, and the Steelhead Trout. Some cat colonies can grow quite large and consist of more than a dozen cats. These feral cat’s wild diet could possibly impact the available prey base for native predators like the Gray Fox and Red-tailed Hawk.

Another impact on wildlife associated with feral cats are the feeding Cat Feeding Station Adobe Creekstations. They are maintained by volunteers or private citizens to help keep cats healthy. Some feeding stations receive a delivery of multiple pounds of food each day. The feeding stations can often be found in or around wildlife designated areas. One sign we found on a feeding station, bordering the habitat of the small, ground nesting, Western Burrowing Owl read “this is a humane project for 100% benefit of our feline friends” but is it humane for the wildlife? We hypothesized that the cat food is not curbing the cats will to hunt. Like a house cat that is well fed, if its let outside it most likely will start stalking the first little creature it sees, hungry or not. Could it be their predatory nature?

Skunk at feedin station

After witnessing cats hunting in a few of these well fed colonies we began to discover that wildlife was eating the catfood as well. We found kibble in the scat of Raccoons and Gray Fox and Greg Kerekez personally witnessed skunks and many species of birds eating from the feeding stations. From his notes on May 14, 2012 he observed two species of bird, California Towhee and Oak Titmouse take the cat food back to the nest to feed their young.

Robbin with cat food  We focused our camera lenses on the piles of cat food and were amazed at the amount of wildlife that was utilizing these feeding stations. Bill Leikam set up a trail camera on a feeding station in the territory of 4 feral cats. The cats territory included a pickleweed marsh and meadow habitat which bordered an office complex where the feeding station was located. The feeding station is filled each afternoon Foxes at feeding station with over a pound of food, by an civilian who received the property owners permission to feed the cats. Bill also received the property owners permission to conduct the trail camera study of the cat feeding station.We’ve analyzed the first 11 days of video footage. Wildlife made 96% of the visits to the feeding station.

Two skunks and a Raccoon at feeding station

Night after night Skunks and Raccoons fought each other over the cat food. Skunks dominated the bowl with 74% of the visits, up to 5 skunks at a time would fight over the bowl, the Feral Cat feeding Station pie chart most aggressive skunk has a stomach the size of a beach ball, probably from eating so much cat food. Raccoons were next in line at 15% of feeder visits, some also looking overweight. The Gray Foxes made up 7% of the visits and were the most calmly tempered, they arrived early and shared the bowl with one another willingly and would quickly give it up if a skunk or raccoon entered the area.

Cat at empty feedin station

The targeted species, feral cats, made up only 4% of the visits and frequently arrived to an empty bowl. This means that wildlife is eating almost all of the food at this feeding station. We hypothesize that these feeding stations are influencing aggressive behavior in the wildlife and could impact the health and weight animals. With so many mouths eating out of one bowl this feeding behavior could also possibly aid in the spread  of disease.

5 Skunks at the bowl

The people maintaining these feeding stations would benefit from looking into how wildlife uses their feeders. They may be affecting the natural cycles and health of wildlife and the cats may be a minority at the feeders.  The feeders have many possible negative implications for wildlife. For wildlife’s sake, we might want to start looking at putting restrictions on cat feeding stations in and around wildlife designated areas.

We realize that one feeding station does not speak for all and at some stations  we’ve seen cats waiting to be fed when the feeders are filled. This is why more study of multiple feeding stations needs to occur. We encourage people involved in feeding the feral to monitor their feeders for wildlife activity and to not leave bowls of food unattended overnight.

To review the preliminary data from the cat feeding station click the link below.

Feral Cat Feeding Station Data ©Urban Wildlife Research Project 2013

22 Comments Add yours

  1. Dr. Johana van de Woestijne says:

    There are four feral cats that have taken up living in my one acre garden in Los Altos Hills. They hunt the California Quail flock that passes through my yard every morning. They drink from the bird bath. If I put quail food out, they actually eat the seeds. They pounce on fledglings that sit on the ground. They love killing newly hatched quail. They toy with lizards and then don’t seem to eat them. I’ve seen them carry off the brush bunnies, which I enjoy seeing. I do NOT know if someone is feeding them. They do not appear to have clipped ears or to be neutered (as evidenced by regular litters of kittens in the yard). I’m wondering if someone is feeding them, because they look large and healthy. They hunt morning and evening, but I’ve never seen them eat what they kill. They mostly just toy with their injured prey. My feeling is that these rururbian feral cats are having a large impact on the native wildlife in my garden. Would you be interested in collecting mobile catcam data on the behavior of these rururbian cats? I’m thinking of a cam around the neck, so the cats movements can be tracked for a few days. I’m going to have to figure out how to trap them, before they breed again and cause even more damage. Maybe their behavior would be worth studying briefly, as relates to their impact on our local wildlife. Also, I think it would be valuable to find out if they are being fed at a feeding station.

    1. I should clarify my comment about the brush bunnies. I enjoy seeing the brush bunnies. I do NOT enjoy seeing the feral cats hunt them and carry them off. The brush bunnies seem to have an unfortunate defense of freezing in fear and defense, unlike the jack rabbits. I think real data documenting the activities of our local feral cats would be useful. They stalk the hummingbirds too, which is very sad to see too.

    2. Suzi says:

      Hi hun. I can understand that this upsets you. Why don’t you start a trap/neuter/return program for the sake of the creatures that more and more litters will impact? It doesn’t just have to be the cat lovers who do this…anyone concerned about a growing cat population would benefit from trap/neuter/return! These colonies start with just 2 cats dumped by an owner, and grow from there. If everyone would be forward thinking, they would trap any cats seen, and avoid colonies from starting or growing to a problem number. Since cats are considered a domestic animal, harming them is against the law, so the next best thing, even for someone who hates cats, is TNR.

      1. Aaron says:

        It has been proven that TNR does not do anything to control the feral cat population.

      2. sam wood says:

        TNR does not stop the impact on the environment. TNR is a failure. If it worked TNR programs would be done in 7 years THEY ARE NEVER DONE. Cats need to be removed permanently and right away. I kno I know vacuum effect right kill a cat another takes its place. Explain this then the cat fairy drops a new one off or and existing cat in the environment moves in. Great news no cat fairy. More great news we have the cats coming to us now and they ALL can be removed. Yes if TNR says they can get all the cats so can a removal program

  2. _MG_9966.jpg
    Here is a photo of a cat very near the feeding station(s) at Google, Shoreline Burrowing Owl Nesting grounds. I almost always see and can photograph feral cats in the Burrowing Owl nesting area (Vista Slope). The half-time park ranger at that time told me that in a six month period he had already trapped 24 feral cats in there. The cats seem to be fed at a colony feeding station but then continue to hunt in the Shoreline Burrowing Owl nesting area. I gave up on photographing the feral cats in the Shoreline Burrowing Owl Nesting grounds, because the park management seemed fully aware of the situation. It seemed that the feeding of a colony adjacent to the Burrowing Owl Nesting Grounds at Shoreline was contributing to the concentration of feral cats in a sensitive breeding bird nesting area. Not all the cats appeared to have been neutered, as I saw kittens as well. Whenever I’ve seen cats in the Burrowing Owl Nesting Grounds at Shoreline (Mountain View California) they are either sleeping or stalking. Feeding the cats doesn’t seem to prevent the stalking and hunting behavior. My photos and observations were from 2012. I do not know if the cat colony at Shoreline Mtn View has been terminated or relocated, but I hope it was removed. The TNR policies seem very destructive to local wildlife, in my observation.

    1. http://www.flickr.com/photos/johannacalifornia/7511170424/
      This is correct link for the feral cat with prey in the Burrowing Owl Nesting Grounds, where they hunt daily. I should add that there are no residences immediately adjacent to the nesting grounds, which is why I thought the source of dozens of feral cats was probably the feeding station at Google.

  3. s torngren says:

    Why doesn’t this address the impact on songbirds? Cats kill BILLIONS of songbirds and native species of mammals per year. http://www.nytimes.com/2013/01/30/science/that-cuddly-kitty-of-yours-is-a-killer.html?_r=0There is no shortage of cats in this country, and we shouldn’t be encouraging more.

  4. A.D. says:

    The entire rationale behind Trap-Neuter-Vaccinate-Return (TNVR) is to reduce the number of stray and feral cats. And, I have to add this because everyone seems to forget — stray and feral cats are a PEOPLE problem — not a cat problem. People do not get their animals spayed/neutered as they should, they move and put the cat outside, and voila’, you have a stray cat that potentially becomes a feral cat. It is not the cat’s fault. People need to take responsibility for their pets, all of them.

    1. Jim Levine says:

      In order for TNR to reduce predation, it has to first reduce populations. To reduce populations, you have to neuter > 75% of the cats in the area (and by area I mean a city or town because if you just TNR a colony, you continue to have immigration and abandonment because of the food). TNR activities maybe reach 5% of the cats at best, and hence have no affect on overall population size. In addition, TNR does nothing to stop ongoing predation on native wildlife. Your best bet is to stop feeding and trap and remove continually. Feeding only increases resources and increased resources increases populations. It’s not rocket science. If I saw predation of native wildlife, I would buy a live trap and begin trapping and removing. If you think that is cruel because the cat may be euthanized, isn’t it more cruel to let it continue to kill native wildlife until it finally meets its own inhumane death from a car, a coyote, or a disease?

      1. A.D. says:

        Thank you so much for your response, Jim. The city I live in has a huge percentage of TNR’d cats, almost 75%. And, I do not buy into your inhumane death ideas, only because I currently have colonies that have cats that have cats who are 12 to 16 years old. That is because feral cats are smart, they receive adequate food/water/veterinary care from the caregiver (me), and they want to live a long, happy life like any other cat. I wish that you could visit my colonies and see for yourself how happy they are! And, over the past 15 years (and I am being totally honest), I have only seen 2 dead birds. I think that adequate food certainly helps.

        Thank you and if you consider trap and kill, just remember there will be more — it is not a solution.

  5. Mike Miller says:

    Unfortunately A.D., you’ve just proven that TNR does not work to eliminate or even significantly reduce the number of cats. You’ve been doing it for 15 years! And you still have colonies! If it worked as TNR advocates claim it does you’d be rid of your cats by now. And just because you rarely see dead birds does not mean they’re not killing them. Search youtube for “cat kills bird”. You’ll find well over 60,000 videos. I suggest you watch a few if you can stomach it. TNR isn’t humane for the cats, and it certainly isn’t humane for wildlife, which continues to suffer at the paws of these cats. Quit feeding the cats and eliminate other food sources. That would be a huge step forward in eliminating this problem.

  6. 25% Reduction already _ Let work together to keep the momentium going...... says:

    The proof that TNR works is in the Santa Clara County shelter statistics. 25% fewer stray cats and kittens have been brought into to our local shelter over the last few years, due to high-volume TNR effort, which slows the breeding and reduce the number of litters of kittens born each year. After the 25% initiial reduction, the shelters are continuing to see a continued 8 to 10 % in cats entering shelters each year. The trends and the ever shrinking number of free-roaming cats (owned or feral) being brought into locat shelters , shows that trapping & fixing all out door cats (tame or feral), encouraging resident to also spay/neuter their own pets, and encouraging folks when they adopt cats to keep them indoor only, IS working. Public education is the key here. Please promote responsibile pet ownership, and promote and encourage Spay/Neutering of all pets (either owned, or those allowed to roam outside) and encourage people to adopt from locat shelter (which take in and rehome outdoor cats) and for the new owners to keep them as indoor cats. Outreach and continued education to the public is the key….and it is working. Buy getting more people to spay their pets, tnr any all all cats they feed and keep those cats they own inside, we have already successful lowered the outdoor cat pupolation by 25% over the last 3 years ! Now , that is progress ! So, let what is working, keep working !! If we keep going at a 8 to 10% continued reduction rate, as has been demonstated in the local shelter statistics, we will actually be able to acheive what bird-lover and cat-lovers alike are BOTH striving for….FEWER free-roaming cats ! We are almost there folks….let keep working TOGETHER, and not against each other, to get there. We put too much energy into producing opposing views, when in reality bird-folk (who love all animals) and cat-folk (who love all wildlife) really are ON the SAME SIDE, we both want FEWER free-roaming cats, and those out there to finds homes ! So, let’s stop the silly back and forth fighting, and work on this together, to identify hot spots, so we can FIX them, and so that we can get to where we want to be….which is to arrive in a place where all species are protected and treated humanely by man.

    1. tpsgreg says:

      Thank you for your comment. Thank you to all who have helped reduced cat populations and to those who care about the felines and wildlife. You are right, we do need more education, for the public and education for the TNR folks that feed the feral. The majority of feeding activity I’ve witnessed has been harmful to wildlife. Better feeding training and techniques are needed to reduce impacts on wildlife. You can’t fix a problem by creating another. 5 Obese skunks fighting it out over cat food, in front of family owned businesses is not affective TNR.

      I agree we are on the same side, What you call “silly back and forth” I call discourse. We must continue debating and research to discover and adapt our efforts to make TNR even more effective at saving/protecting wildlife and reducing cat populations. Wildlife should not be eating an unnatural diet.

    2. Diana says:

      Please what is the source of your data? Is it online? I need to know soue urgently

  7. woodsman001 says:

    Here’s another good TNR facts site that was put up not long ago.


    There are tomes of links and information there that give to everyone the clearest picture of all of what their failure of self-serving TNR-delusions are really all about. Not to mention what every last TNR advocate disrespectfully does to every other life on the planet — animal and human included. Everyone involved in TNR might be particularly pleased with the photos there of what their loving and “humane” euthanasia by “attrition” truly looks like. It’s no longer their delusional, safe, and psychotic “out of sight, out of mind” way of torturing cats and other animals to death anymore.

    I hope they enjoy it. Everyone else on the planet already sees these phenomenally ignorant TNR freaks for what they truly are — torturers of all animal life on earth — just because they are too spineless and heartless to give a cat a humane death the one time when they could have died peacefully that way. Heartless and cruel doesn’t even begin to describe these mentally crippled TNR cat-lickers.

  8. woodsman001 says:

    I don’t see anyone dumping cats where I live anymore. They don’t even adopt more than can be kept under lock & key 24/7/52. When driving through the area I don’t see even one cat on anyone’s doorsteps anymore. I always keep an eye out to see if there are more free-roaming cats that will have to be shot. And if I’ll have to leave fish-oil trails on all the roadsides again, leading right to my IR surveillance system and laser-sighted rifle. (You can read some of the most effective methods I invented to rid my lands of hundreds of their vermin in only two seasons, posted here: americanhunter D0T org SLASH blogs/arkansas-will-trap-feral-cats The eradication of these disease-infested invasive species vermin was so complete and effective that cats are non-existent from my area FOR OVER 4 YEARS NOW. Not seen nor heard a single one. So much for their deceptive and manipulative “vacuum effect” lie and myth BS too, eh? All erroneously based on one simple fact: cats attract cats. Destroy every last one and there are none there to attract more of them. If you want more cats keep even one around, more will find you and you’ll be up to your ass again in no time with these destructive disease-infested vermin piece-of-sh**s.)

    Leaving ANY of their invasive species cats outside in my area means certain death for their cat, their cat’s further existence can be counted in hours. You’d think everyone else could learn from this simple lesson. The quickest way to solve an unwanted animal and irresponsible pet-owner problem is to let everyone know that you will quickly and humanely destroy every last one of their unwanted, uncared-for, or unsupervised animals for them. They either grow up fast or, far more plausible, dump their animals elsewhere to become someone else’s problem.

    You just can’t be an enabler of criminally irresponsible spineless and heartless idiots — or they remain that way. (At least where you live, anyway.)


  9. JoAnn says:

    I manage a feral cat colony. I know it works. I’ve been doing it for almost 5 years and not only are we down to one litter of kittens in my colony. But my colony is healthier because of it. I can’t control the strays that show up for a free meal but I guarantee that if I see them twice I get out the trap and get her into the vet to TNVR. It works. My colony is 15 strong. I’m fortunate my neighbors see the difference that I’ve made and welcome the absence of the fighting , cat wailing , scrouging the garbage cans. The one’s I can pet I give a flea treatment to every month. The one’s I can’t are on their own. I never leave food out at night for the very reasons you spoke about,varments. The food at the station is gone by evening. Only fresh water remains.

  10. lopoas says:

    Feeding feral cats and keeping unenclosed colonies of cats needs to be outlawed. It is not good for our wildlife to be eating manufactured junk food. TNR does not work. Reduced shelter intakes mean less cats are being brought in, not that there are less cats out there. A s/n cat will still continue to kill. The death and mauling of wildlife does not magically stop by sterilizing a few cats. Why are the TNR folks not volunteering at wildlife rescues to euthanize the animals and birds brought in that are skinned, dismembered, scalped, and broken, but still alive that cats have mauled? Why is one feral cat worth more than native species and the chain needed for their survival in the wild? How can anyone say that TNR saves lives? It still kills and kills more than just wildlife. Sterlilized cats still get hit by cars, contract diseases, get parasites. and are at risk of cruelty. The food you are putting out for cats is from animals who are factory farmed and suffer horribly. I would doubt that any of the foods are humanely farmed and full of the best ingredients that is left out for strays. Those lives don’t matter to the feeders, either. There is no way that you can have uncontained animals and provide them the necessary veterinary care and treatment needed for a domestic animal. Having livestock taught me that lesson years ago. Feeders want to feed cats, but they don’t want to take on the responsibility of owning the animals. If you truly care for the cats the buy land and build a safe enclosure for them.

    1. Suzi says:

      So Iopoas, do you think cats will magically disappear if not fed? Do you propose to kill all predators in the animal world….or you just reserve that treatment for cats? You’re okay with snuffing out the life of the cats…so there are no factory farmed animals? Do you also advocate doing away with all wildlife sanctuaries for meat eating animals…because they eatfactory farmed animals? Perhaps we should go so far as to only allow homeless and hungry vegans to be fed/assisted in living so as to do away with the problem of factory farmed animals on an even larger scale? Where do you draw your line?

  11. Alexys Roberts says:

    Interesting reading every ones comments of the feral cat situation. I recently participated in the capture neuter release program. I live in an apartment complex and there is quite a large colony of feral cats here. This is a people problem as many pets are abandoned when people move. Cats live up to 18 years, so all the one year old that have been spayed or neutered will be around for as long as they live. There will still be cats left behind by the poor, so the population won’t stabilize until the people problem is sorted out. But the populations are reduced by this program, and the more each individual is involved in helping out by catching and releasing, this population will be reduced in the long run. When we plan cities, we should have places where wildlife can live in harmony with human populations.

  12. Sara says:

    This is a very limited, unscientific study. It looks only at one feeding site, with one method of feeding, one time of day of feeding, and one very specialized location of study (wildlife area). It has not been replicated, nor has it been peer-reviewed. I have been assisting with TNR programs for over a decade. I also tend to a group of stray and feral cats. I began trapping on this property roughly 7 years ago, when multiple litters of kittens were being born to each female each year, and the toms prowled the neighborhood looking for more. The cats were skinny and often ill. Since then, I have fixed every unowned cat found on my property, and have found homes for the kittens born to feral mothers. I vaccinate them and treat them for any medical conditions. Aside from cats that I have taken in from other homes, the cat population here has declined as the kitties age and pass away. There is abundant wildlife here: lizards,toads, birds, frogs, etc. and I keep an organic garden where I specialize in native plants. I may not be an amateur photographer of the caliber used in this article, but I do have external cameras, and even rats are unafraid to come onto my porch to steal seeds from my caged birds, with 3 cats lounging out there almost all the time. The cats are eager to be fed and while a certain large raccoon does sometimes try to scare them away from their lunch, virtually all of the cat food is consumed by the cats. Also, I am halfway to my Veterinary Technology degree. In my first lab class we all had to dissect the bodies of feral cats that had been picked up and euthanized. Out of all of those dead cats, only one had the remains of a wild animal within his or her body: a mouse. I recall a lesson from my youth, when we opened up owl pellets and examined the tiny remains inside, the remains of, yes, more mice. Should owls also be denied their place in the world? The cat that we recognize today has existed for 100,000 years. They are part of ecosystems, just like all animals. They deserve more respect than to be treated like parasites.

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