Deadliest Catch

The occasional dead mouse or bird that Fluffy drops on your doorstep may not seem like a great loss for wildlife. But a new study suggests that the cumulative effect of hunting by domestic cats is staggering: Kitties are killing about 8 to 24 billion birds and mammals in the U.S. each year.

Thanks to humans, domestic cats have spread around the world and pushed numerous bird, mammal, and reptile species on islands toward extinction. But people often assume that the number of wild animals killed by cats pales in comparison to the number that die from crashing into buildings, being run over by cars, or other human-related dangers.

The estimates of cat-related deaths in this latest study tell a different story. Domestic cats in the U.S., not including Hawaii and Alaska, kill 1.4 to 3.7 billion birds and 6.9 to 20.7 billion mammals each year, the study authors say in Nature Communications. Cats without owners account for 69 percent and 89 percent of the bird and mammal deaths, respectively.

“Our findings suggest that free-ranging cats cause substantially greater wildlife mortality than previously thought and are likely the single greatest source of anthropogenic mortality for US birds and mammals,” the team writes. About two-thirds of birds killed by cats are native, as are most of the mammals killed in the suburbs and countryside.

Even though unowned cats are responsible for most of the carnage, cat owners aren’t off the hook. People should make an effort to control their pets by restricting the cats’ time spent outdoors, the team says.Roberta Kwok | 1 February 2013

Source: Loss, S.R., T. Will, and P.P. Marra. 2013. The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications doi: 10.1038/ncomms2380.

Image © Micha Klootwijk |



  • Savina Snell February 6, 2013 at 5:57 am

    You do know that the studies shown in that magazine are half a century old and pulled from a discredited source right? You also now that current studies have put humans on top of feral cats in the destruction of habitats and pollution right? Before claiming something is a “new” study, please get all the facts. There is more information in the link that is in the web site box as a source. Again the whole study you’re quoting is horribly out of date.

    Please get your facts straight next time. And again in case it doesn’t show: Nico Dauphine is a discredited researcher who was charged for the poisoning of cats and fired from the Smithsonian yet you are still going to believe Nature Conservation?

    Claim all you like to be doing something good, all you’re doing is giving people more of an excuse to kill cats and provoke animal cruelty. TNR is more useful and has better research then the darn article.


    • roberta February 7, 2013 at 4:40 pm

      Hi Savina,

      I’m not sure what you mean. The study described in the story was published on January 29, 2013 in the journal Nature Communications. The authors describe their methods as follows:

      “We conducted a data-driven systematic review of studies that estimate predation rates of owned and un-owned cats, and estimated the magnitude of bird and mammal mortality caused by all cats across the contiguous United States (all states excluding Alaska and Hawaii)… After excluding studies that did not meet a priori inclusion criteria designed to increase the accuracy of our analysis, we developed probability distributions of predation rates on birds and mammals. We combined predation rate distributions with literature-derived probability distributions for US cat population sizes, and we also accounted for the proportion of owned cats allowed outdoors, the proportion of owned and un-owned cats that hunt, and imperfect detection of owned cats’ prey items. We generated an estimated range of bird and mammal mortality caused by cat predation by incorporating the above distributions—including separate predation rate distributions for owned and un-owned cats—and running 10,000 calculation iterations.”

      So while they do draw on data in previous studies, they run new analyses to come to their conclusions. You can find more details here:

      Nico Dauphine is not listed as one of the authors on the study. The study authors are Scott R. Loss, Tom Will, and Peter P. Marra.

      Hope that helps,



      • tyler gill March 18, 2013 at 9:30 am

        I do no think that kittens are all that bad. My cat just had some and they are very nice.

      • KJ March 24, 2013 at 12:42 am


        The issue of Nico Dauphine and her animal cruelty conviction matters because the authors are her close colleagues. Specifically Marra was her direct advisor during the time she engaged in, and got caught trying to poison cats in an area devoid of vulnerable bird species. It should be noted that even after being convicted, Marra allowed her to resign, instead of firing her. These factors raise legitimate and troubling questions of the authors motives and the study’s validity.
        Please follow the link for additional information.

    • tyler gill March 18, 2013 at 9:31 am

      just because you found a dead bird that a cat killed does not mean a darn thing. The cat could have been starving.


  • John February 6, 2013 at 7:16 am

    Savina does not explain why Nico Dauphine is relevant. The paper cites a range of data. I don’t think anyone would dispute that humans are the biggest threat. But since when did two wrongs make it right? Even more worrying is the implications of Toxoplasmosis carried by cats, feral, tame and TNR.
    I hope the magazine will deal with this important issue


  • Bob February 6, 2013 at 7:36 am

    Thank you for the above comments. In the first one I was most interested in the Nico Dauphine issue, yet another example of attack the witness or shoot the messenger. The quote from the Humane Society was especially interesting,
    “Justice was served today. Every animal, regardless of breed, age, condition or any other factor, deserves protection from cruelty and abuse,” Lisa LaFontaine, the group’s president, said in a press release yesterday. Does the term “every animal” include native birds? It seems to me that getting ripped apart by someone’s cat is cruel and abusive. “The trouble with a kitten is that eventually it becomes a cat.”
    Ogden Nash

    I don’t know of a proven way to get rid of excess cats, but humans have done a pretty good job on wolves, especially in the United States. I wonder if shooting and poisoning (the latter is still illegal but none-the-less continues to occur almost daily) is cruel and abusive to wolves? Interesting issue, perhaps the Humane Society should jump on this one so that “justice can be served?”


  • John February 6, 2013 at 7:57 am

    The article is interesting, but does not go very far beyond that. It doesn’t mention the huge number of predators to birds and native mammal species outside of the urban context. Predator-prey relations are likely to impact upon the prey, but this is neither unusual, nor alarming. Cats are a part of the human landscape and to attempt to remove them would be artificial and absurd. Instead we should be providing habitat within cities that is of benefit to wildlife rather than looking for a handy scapegoat.


  • Bob February 6, 2013 at 8:36 am

    Bird mortality — The wind people blame the building people. The building people blame the cat people. And of course, the cat people blame everyone else. No one takes any responsibility for the bird mortality we are experiencing. It is always ‘the other guy.’ The assertion from that cat people that this is just cats being cats and that the bird mortality is no big deal, is patently offensive and absolutely hypocritical. Get real and own up to your part in bird mortality and stop pointing fingers.


  • Ruthann February 6, 2013 at 8:52 am

    All this prating about cats is a waste of time. The birds are still dying at alarming rates. If anyone really wants to understand why they’re disappearing, they just have to look in the mirror.
    Habitat loss dwarfs all other reasons for bird mortality.
    As for cats, it’s still all about people – people who refuse to take responsibility for their pets – to neuter them and keep them confined.

    But I forget, dealing with people’s entrenched habits is way too difficult. It’s just so much easier to blame cats.


  • tom February 6, 2013 at 10:03 am

    I would certainly agree with Bob, who has it exactly right. Ruthann also. I have lived with and dearly loved cats all of my long life. Nevertheless, allowing your house cat to roam is utterly irresponsible. It would seem that many, or even most, cat owners are in denial of the facts, and blinded by love. Much of the other commentary consists of either faulty reasoning or is downright foolish. I have watched feral and domestic cat behavior all my life, and they are huge destroyers of all wildlife, second only to humanoids. Cats roaming outside our houses should be destroyed, and much as it pains me, I will continue to do my part.


  • Randy Hunt February 6, 2013 at 2:50 pm

    I guess the coyotes in our neighborhood have been on the birds’ payroll for quite some time. We have lost half a dozen felines to these canines!


  • The Green Buzz: Monday, February 4 | Volved February 6, 2013 at 11:22 pm

    […] Kitties=stone-cold killers. (Conservation Magazine) […]


  • Chris February 8, 2013 at 2:02 am

    Cats roam the streets here in Cairo like dogs do in Mexico. They are everywhere but do serve a purpose. Garbage is thrown into the streets regularly. Trash collectors eventually pick it up but it may sit there for days. If it wasn’t for the cats, the rodent population would be through the roof. With all of the garbage, I have never seen a single mouse, much less a rat. This isn’t denying the fact that cats are destructive of wildlife in many areas but in this case, they are a benefit. To hunt birds would take a lot more work and energy. Uncontrolled hunting and netting during migration is the big culprit of bird mortality here. When cat populations explode in an area, you notice suddenly that many have “disappeared.” I think people poison them here. Cruel but that’s what they do to control their population.

    It all comes down to the actions of humans doesn’t it?


  • Penny N February 8, 2013 at 1:50 pm

    I spent many years and mucho dollars feeding birds. Then, the raptors moved in and have decimated the other bird populations. Every raptor known to Michigan eats in my yard. I paid to get special screens so the “big raptors” didn’t get caught in the screens when they miscalculated – (that’s also expensive.) I have many wild critters in my neighborhood, my two cats enjoy watching…from behind the windows. I no longer feed birds…I can’t stand the carnage.


  • Mike Fitzpatrick February 9, 2013 at 4:58 am

    I taught high school biology for 33 yrs. I stressed wildlife conservation and ethical treatment of ALL animals in my classes. When I talked about cats outdoors and small animal kills due to cats, the vast majority of my cat-owning students objected to indoor-only cats,BECAUSE they did not want to deal with the litter box! Ugh! Gross! So there you have it–cat shit= bird/mammal predation!


  • Dana Price February 13, 2013 at 9:44 pm

    I am wondering about cat impacts on URBAN bird populations and whether cat killing really has a population-level affect compared to habitat and food availability. I live in Albuquerque, NM. Most of the birds in my yard are common urban birds like house sparrows [non-native], white-winged doves [native and common], house finches [native and common]. These are all super abundant. My cats have killed doves. Is it reasonable to assume that cats are going to kill birds in proportion to their abundance? So is it a problem when they’re killing common urban birds? I have smaller numbers of goldfinches, bushtits, hummingbirds in summer, one pair of thrashers and one roadrunner in the neighborhood. Of all these I’ve only found immature goldfinches killed by the cats and this is probably because the goldfinches hang around the yard eating thistle seed and wild sunflowers.

    I’m not looking for a thrashing for letting my cats outside. I got them both off the streets so at least they aren’t hunting full time, and as they get older they are getting lazy and spending less time outside.

    I would really like to know what is limiting bird populations- is it mortality or is it lack of suitable habitat? Won’t populations expand to the carrying capacity of the habitat even with predators around? The fact that I have large numbers of sparrows and doves but few goldfinches and bushtits suggests to me that the health & size of urban bird popualtions is more about altered habitat than sheer mortality. Thanks for your thoughts.


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