[Amanda] Great, well welcome, everyone. It’s a pleasure to welcome you to the Monday night seminar series here at the Lab, and I’ll extend that welcome to those of you in this room as well as those of you who are streaming online this evening as well. So it is a terrific pleasure for me to introduce our speaker tonight, Dr. Pete Marra. 

Pete is the director, or the head of the Smithsonian Migratory Bird Center. He’s been working at the Smithsonian as a scientist since 1999, soon after he had finished his PhD at Dartmouth College, and his master’s at Louisiana State University. 

We’re really fortunate to have Pete here with us because he’s one of the leading avian ornithologists and scientists working out in the world today. He has a variety of projects domestically and internationally, spanning a wide variety of topics ranging from ecology and conservation to urban ecology, disease ecology, movement ecology, and he really distinguishes his work from what a lot of people do by working at the interface between basic and applied science. 

A lot of his work relates in some way to trying to understand how bird populations respond to changing environments, and including human activities. One of the things that really impresses me about Pete is his ability to engage with diverse audiences on topics that are really important in terms of conservation. 

And so he’ll be doing that with us here tonight, and this time related to the science surrounding one very topical and controversial issue. And that is how free-ranging cats can impact bird populations. 

And now we understand that this is a topic that does raise a lot of emotions for many people, and we’ve heard some of that expressed to us even in planning this seminar tonight. So I want to make it clear that neither those of us here at the Lab nor our speaker Dr. Marra are against cats. 


We care about cats. Um in fact many of us at the Lab who work here also own cats, indoor cats. And we also recognize that that emotion, that deep concern, that desire to engage in conversation is a really good thing. We value that, we encourage that. At the same time we also are asking that people be courteous and respectful of one another tonight, and also of our speaker. 

And to be sure that he has the opportunity to share with us the science that he wants to discuss, and his perspectives without being interrupted. And you will have an opportunity to ask Pete questions after he finishes his discussion, um here in this forum, as well as afterwards at the book signing. So with that Pete, it’s a pleasure to have you. 

[Pete] Thanks so much, Amanda. 


Well I really appreciate you all coming out tonight, and everyone who’s live streaming, I really appreciate you all tuning in. If you couldn’t tell they’ve been little disagreements about this issue, 


a little bit, since it came out, but it’s it’s, I can’t tell if it’s been overshadowed by the election or not. 


But it’s it’s, there’s been a lot of controversy in the air over the last couple of months. But with that, let’s talk about cats. 

[Photos: Four portraits of cats] 

Cats are quite the amazing creature, there’s there’s no getting around it. They are sort of the supreme pet in many many ways. They exhibit all these incredible behaviors chasing, pouncing, chasing balls of yarn. They do all sorts of neat things, everything from stalking, and they chase laser pointers, and feather toys. 

In many ways they’re still a wild animal, yet they’ll curl around your neck, they’ll sleep on your lap, they’ll rub against your leg. They do all these incredible things. They’re this powerful independent beast that you have in your home, yet they they’ll come up and they’ll purr in your neck, and they’ll let you scratch scratch their chin. 

I would argue that they probably are America’s favorite favorite pet. 

[Photo: Cat holding down a bird] 

But cats are predators and they reproduce almost like rabbits, two to three litters a year sometimes. And outside, this is the point we’ll talk about tonight, they can be incredibly destructive to wildlife. And to people, in fact. 

You see cats, though, are doing really what just comes naturally to them. Cats are pets or pests depending upon the situation we put them in. We’ve set this all up. We’ve sort of in essence because of our domestication of cats, we have domesticated them, we’ve set this situation up as humans. They again, they are just doing what they should be doing, what comes naturally to them. 

And outside, these consequences are highly significant. In addition to the impacts on biodiversity, they also have, we also have consequences on human health, and also on their own well, on their own health. The cats outside, some estimates are that they live half as long as indoor cats. 

So this evening what I’d like to do is to describe the current situation with the outdoor cat. Basically, talk about the book a little bit. I want you to buy the book,


so I’m not going to say everything in the book. In fact the most exciting stuff is still in the book. So, but the thing I want to emphasize is that the book is based on data and science. 

Hundreds of papers, scientific papers, 99% of them are not mine, okay. In fact there’s only one paper that I referred to that’s mine. It’s a big paper, but it’s still it’s only one of the papers. All the other papers that I reference and talk about in this book, that Chris and I talk about in this book, are not my papers. Their international, and there’s a lot of them. So the science is is clear. 

As I’m talking one of the things that I really want you to think about in the back of your mind, there’s really two big questions. The other question I’ll leave towards the end. 

[Slide text: Should we let cats persist outdoors despite the consequences they have for wildlife and humans?] 

But it’s this question is should we let cats persist outdoors despite the consequences they have for wildlife and humans? And there’s another caveat to that that we’ll talk about because there’s a consequence to this, but I want you to think about that. Given where we are should we let them persist? Should we be wildlife managers? 

[Photo: European wild cat walking on a tree branch] 

So let’s let’s talk about cats, a little bit of background. Globally there are 40 species of cats. You all know the big seven, right. Lions, tigers, cheetahs, leopards, snow leopards, I always forget the last few, but you know where I’m going. Then they are 33 other smaller species of cats that are really fascinating animals. Things like the sand cat, the serval, the margay, the flat-faced cat. There’s all these really cool cats, all over, all over the world, many in the tropics. 

This is a European wild cat, and they’re actually 20 or so subspecies of European wild cats. And the domestic cat is thought to have been domesticated from five subspecies of the European wild cat. Ironically they’re, they, many of these populations in like Scotland and other places, France, are highly endangered. Some like in Scotland are down to about a hundred individuals. Definitely the species were brought to its knees due to habitat destruction. This is going to be a theme that I’m going to sort of try to get into your heads, brought to its knees by habitat destruction. 

But now its greatest threat is inbreeding with domestic cats, and the diseases that they carry. So that’s a decision that people have to make. Do we remove cats, domestic cats, from the wild to save another species?

This is the ecological dilemma, this is the dilemma that people on the front lines of science and conservation have to deal with. So I want you to think about that, so that’s another sort of question that I want you to have in the back of your mind. Is it okay to kill one species to save another? 

Again, this is what the book goes into, so you got to buy that book. But in this case you know it’s looking at the extinction of a native species because of now inbreeding with a domesticated species. So that’s that’s that’s a problem. 

But about 10,000 years ago cats became domesticated. They they are thought, there’s a variety of theories, the the the best theory is that was, that was about the time when we started to contain water, grains, houses, and those grains and houses started to attract house sparrows and mice, and that attracted European wild cats. 

Turns out there’s there’s a genetic underpinning to tameness. And over time certain individuals became more tame, whether they were captured and and bred selectively, or they just there was some sort of selection for tame individuals over time, nobody knows. You can’t recreate this. But sometime, somewhere in the fertile crescent around 10,000 years ago domestication of the cat was thought thought to happen. 

[Image: Pablo Picasso’s Cat Catching a Bird painting] 

Since then, cats have invaded our culture. They are, there are sculptures, Greek sculptures, Roman sculptures of cats. They’re in ancient artwork, Pablo Picasso deeply love cat, cats. He was, he was mesmerized by cats. This is one of his his famous paintings called Cat Catching Bird. It’s thought to be a pregnant female, but cats were the subject of many of Pablo Picasso’s 50,000 paintings or so.

Mark Twain love cats. He was often seen walking with a cat draped around around his around his neck. 

[Images: Cats in popular culture, including Sylvester, Garfield, Hello Kitty, and Grumpy Cat] 

And of course cats occupy a lot of popular culture as well. Sylvester, Morris the cat, Morris for president, that’s sounding pretty good right now, in fact. 


Garfield, Little Kitty, Sylvester, and of course Tartar Sauce AKA Grumpy Cat. 

[Photo: Tabby cat standing and looking up] 

But cats again are part of our modern culture in many ways because people really connect with cats. I didn’t even go into cat videos. There is a, is amazing, lot of them. And I, they’re fun to watch, I enjoy watching them.

There was one recently that had I think something like, I don’t know, 10 million hits. It was like, you know, obnoxious cats. There’s like, you know, cats jumping on babies’ heads, and things like that. 

But yeah I mean people like cat, love cats. And I I totally understand it. But the point that we need to remember is that Felis domesticus is just that. 

[Photos: Sheep, cow, chicken, pig, rabbit, and golden retriever] 

It is a domesticated animal, just like a sheep, just like a cow, just like a golden retriever or a chihuahua, a chicken, a pig, or a rabbit. I used to say that you know cats remain the only species that roam free, although just out west in some wilderness areas in Montana I couldn’t believe the damage done by free-ranging cows on private lands, but that’s a different book, that’s Cow Wars, and horses. 

[Slide text: In the United States: 90 million owned cats- roughly 66% go outside (60 million outdoor owned) -60-100 million un-owned cats- Not clear how many feral cats exist in the US Somewhere between 80-160 million outdoor cats; Images- Tabby cat and group of cats outside] 

But so in the United States how many cats are there? I’m gonna tell you folks it’s hard to count cats, it really is hard to count cats, so we have estimates, these are estimates. And most of what we do in ecology of course is estimate, that’s what we have to do. 

So we can get a pretty good estimate for the number of owned cats. And there are three categories of cats that I think of. I think of owned cats, I think of un-owned cats, owned cats that are inside, owned cats that are let outside, then there are un-owned cats that are outside 24-7, and then there are feral cats. Feral really means that it’s an animal that has no dependence on humans whatsoever. 

We really do not have a good handle on the number of feral cats that we have the United States at all. In places like Australia feral cats are a real problem because there truly are lots of feral cats in the outback causing huge problems for many species. But let’s not worry about feral cats this evening, let’s focus on owned cats and un-owned cats. Those are the two categories we’re going to focus on. 

So there are roughly 90 million owned cats, and estimates are that the sixty-six percent of these go outside or so. That means that about 60 million outdoor owned cats that go outside. Some people have problems with these estimates, they think that the 90 million is actually an underestimate, underestimate now. Underestimate now. That actually this sample that was done by two independent veterinary groups is is, did not sample low income folks. And so they think that this is actually an underestimate. And they asked, some people think that the sixty-six percent that go outside is now an overestimate. 

So yeah, we’ll see. We’re actually starting something called the great cat count 


and I’ll tell you about that in a little while. And so then what about the un-owned cats? Well, this is even harder to estimate. So these are, there’s the five or so different groups that have estimated this. It’s really rough. It’s got huge error bars, but it’s somewhere between 60 to 100 million un-owned cats right, out there. 

But in a lot of the work that we’ve done we’ve used estimates as low as 30 million and up to 80 million. But this is, these are just the estimates. Again these are not my estimates, these are published estimates that are out there. And I do believe that there’s a lot of error around this. 

So we’re trying to figure this out, and there’s a group of us both veterinarians, people, cat advocates, and ecologists and scientists that are going to be setting up some pretty intense camera trapping in a variety of places to try to get a better handle on the number of cats that are out there. Out and, out in the world. 

So in general there’s somewhere between 80 to 160 million outdoor cats out there in the United States, in the United States. That are out, in the outdoors at some point. Whether they’re owned and outdoors or just outdoors. 

[Photos: Various North American bird species, including a swallow, woodpecker, duck, oriole, bunting, catbird, and more] 

So with the rise of cats and cat cat culture and people loving cats, we also saw a really fascinating rise in love of birds in in the early in early 1900s. Thanks to, in large part to the invention of a field guide by Roger Tory Peterson. Somebody who I got to meet and got to birdwatch a couple times with. I love bragging about that because it was a pretty pretty amazing thing to be able to do. 

In North America the diversity of species that we have somewhere between 750 to 800 regularly occurring native species, their diversity, their colors, their songs, they’re just just amazing. I think most people in this audience would agree. 

And the point I want to make is that these species matter, birds matter, right. But we have a commitment, we have, we have a, we have a responsibility to preserve these native ecosystems. We just do. They do, yes these birds and the other wildlife serve really important ecosystem functions, but just you know in terms of our greater good we don’t want to lose these species. 

[Photo: Canada warbler singing] 

But unfortunately species like the Canada Warbler, 

[Photo: Cerulean warbler] 

cerulean warbler, 

[Photo: Brown thrasher] 

brown thrasher, 

[Photo: Piping plover adult and chick on a beach] 

piping plovers. These species are disappearing right before our very eyes. That’s reality. That is reality. Over the past hundred years we’ve seen many species go extinct. The passenger pigeon wasn’t the last one. There have been many other species that have, that have disappeared off the face of the earth. 

And not just the United States, elsewhere as well. Species decline before they go extinct, that’s just reality, that’s what happens. And now we’re seeing up to thirty-five percent of the species in North America declining. 

Yes, humans are totally the ultimate cause of most of these extinctions, no question about it. But there are multiple proximate causes that we we can control, and what we have to do is to figure out how we minimize our footprint, so we can we can stop these declines. We can figure out why these these species are declining. 

The problem is is that now unlike you know think of DDT or other pesticides in the past, there was a single factor driving these declines. DDT, when you remove DDT from the equation, brown pelicans came back, bald eagles are back. Could you imagine. This is, I always tell this because it’s hard to believe, could you imagine trying to describe what a bald eagle was, if they had lost the bald eagle? I just, it’s amazing to me. Every time I see a bald eagle I stop in my tracks. I just hope I’m not driving over the Chesapeake Bay Bridge. 


But it’s always, it’s always, it’s an amazing thing to see. But we pulled DDT out of the equation, all those species rebounded, nothing went extinct. Now folks it’s much more complicated. It’s it’s not just a single factor in most cases. We probably think, we think that it’s probably multiple interacting factors that are happening at different scales. That’s the problem now. We can’t point to one thing. For most of these species that seem to be declining. 

The point is is that some of these things are reversible, and some are not. But we need to figure out what they are and address all of them. 

[Slide text: Consequences, Solutions, Cat Wars; Photos: Cat eating a bird, screened porch, and people fighting with signs that say “Birders Hate Cats!”, “Audubon Sucks” and “I ❤️ Cats”] 

So tonight I want to cover three broad areas. I want to talk about the consequences of cats, talk about the solutions, and then I want to talk about something I refer to as the Cat Wars. And these are going to be the general topics that that follow generally in the book. 

[Photo: Stephens Island wren study skin] 

So I’d like to have you guys put yourself in the 1890s, let’s let’s say 1890. No cell phones, no electricity, no fax machines, no fake news on Facebook. 


No planes, and the boats that were available, which was the primary mode of both regional international movement, were made of wood. If a wooden boat hit a rock that boat would go down.

In fact that’s what happened, several hundred sailors lost their lives right around in New Zealand, right around Stephens Island, and the New Zealand Maritime Division Association, whatever it’s called, decided it was time for a lighthouse on this this really hardened, this remote island. 

And so three, three different families, one guy by the name of David Lyle, who happened to be an amateur naturalist, went out to Stephens Island. He was one of the first lighthouse keepers out there, and he was quite excited about this apparently because he got to pursue a lot of the things that he loved to do, like birdwatching. 

At about the same time, as one story goes, a cat by the name of Tibbles, it’s not clear if his name was really Tibbles or not, or she, her name was really Tibbles. It may have been a couple cats. The details are foggy, but cats went out to Stevens island. Soon cats were bringing in dead animals, to either David Lyle or other lighthouse keepers. And David Lyle, being an amateur ornithologist, was able to identify most, except for a series of 15 specimens that could not be identified. 

He eventually put up these specimens, and this turned out to be a new species. By the end of just one year, or a little over a year, there were no more Stephens Island wrens to be found on the island. So this is the story, this is the first chapter of the book. I call it the obituary of the Stephens Island wren. And it sort of recreates what happened back then in 1894 on this island. 

[Slide text: Cats have contributed to the extinction of at least 63 species (2 reptiles, 40 birds, 21 mammals)- Socorro Island Dove, Chosieul Pigeon, Santo Stefano Lizard, Guadalupe Storm Petrel, Hawaiian Rail, Little Swan Island Hutia (Doherty et al. 2016 Proceedings of the National Academy of Science); Images: Socorro Island Dove, Chosieul Pigeon, Santo Stefano Lizard, Guadalupe Storm Petrel, Hawaiian Rail, and Little Swan Island Hutia] 

But unfortunately, it wasn’t the first and it wasn’t the last species to go extinct due to cats. When we wrote the book there was only one paper that really had done a summary, primarily on islands, by a guy by the name of Medina. It was published in Global Change Biology, and in that book they reported 31 species, 33 species extinctions of reptiles, birds, and mammals. 

A month after our book came out, a paper came out in the Proceedings of the National Academy of Sciences, which is actually a pretty good journal. And this was a much more thorough, thorough analysis, and included some mainland areas including Australia. And they actually reported 63 species of extinctions caused by cats. 

I want to point out that I actually call it contributed to cats, because I also feel like many of these extinctions cats were probably implicated along with other factors, whether it’s habitat loss or other, but they were a primary cause of the extinction. 

This is two species of reptiles, 40 species of birds, and 21 species of mammals. That’s twenty-six percent of the global extinctions during the period of the Anthropocene, second only to rats. That’s extinctions, that means these species are gone off the face of the earth. There’s no, there’s no coming, there’s no coming back. 

[Slide text: What is the magnitude of mortality imposed by cats? Image: Stylized art of cat with a bird on its back] 

So that’s sort of one of the first things that’s that I’m starting to, you know, I’m writing this book, and I’m actually starting to pull this data together, and I’m just amazed at the sorts of impacts that we’re seeing globally. And this is a global issue, this is not just an issue in the United States. 

So there’s this long history of birds impacting cats through extinctions, but if the focus was really on islands. And I, so few years ago we started to ask the question about what is the magnitude of mortality? How many birds are being killed in the United States? What’s the, just the magnitude on say a mainland areas? 

[Images: Crow on the ground, cover of BioScience, graphs] 

And I want to, I want to just tell you a little bit how I got into this. I don’t have a, I don’t have a vendetta against cats at all. I’m a population ecologist. That’s one of the things that I, that keeps me up at night. I try to think about why populations go up, why they decline. What things influence the ability for animal to survive? Or the ability of an animal to to reproduce? What are those limiting factors that drive population size? 

And I like this a lot because it allows me to to pursue fundamental ecology, but really in an applied sense. Because understanding why species decline is really a fundamental biological problem, as well as an important conservation problem. So I really I really enjoy doing that. 

But back in 1999 the West Nile virus first hit. It hit in New York around the Bronx zoo, and a colleague and friend of mine by the name of Tracy McNamara was the first person to to really identify the pathogen of West Nile virus. 

But two years later it came down to the Washington, DC area. And we started seeing a lot of dead birds around. And I started working with Al Dupree and Lloyd Kramer from the New York State Department of Health who had a really big, really impressive West Nile virus lab. 

And we started to really look at West Nile virus dynamics in the DC area. We actually tracked West Nile virus down into Cuba, the first ones to find it in Cuba, and Jamaica, and Mexico, and Puerto Rico. We tracked this this virus. 

But as a population ecologist I was also interested in understanding what the population impacts were of West Nile virus across, across the country on birds. So we started to do an analysis, did this was Shannon LaDeau, and we looked at not just the magnitude but also the impacts of West Nile virus, and published this in Nature. 

But I started to think about these impacts over larger spatial scales. 

[Slide text: How does this direct human-caused bird mortality compare to other sources? Photos: Cat with baby bird in its mouth, wind turbines, skyscrapers, and power lines] 

And this led to thinking about other sorts of things, other impacts of other direct anthropogenic causes of birds over much larger spatial spatial scales. That’s a lot of what we try to do is work locally and try to scale up our findings to bigger and bigger bigger scales. 

So this again led to this larger study of direct anthropogenic bird mortality in the U.S. There hadn’t been one since around 1970, and the one done in 1970 was really not based on a lot of rigorous science, and a lot had really come out. But this was really focusing on the magnitude, not the population impacts. 

So we weren’t really bringing in the population impacts of this, like how much does a population get depressed by a particular thing? We were really looking at just the number of animals that died from a particular thing. 

[Slide text: Median estimate of total annual mortality = 2.4 billion. Un-owned cats—69% of mortality, Free-ranging pet cats—31% of mortality, Loss, Will, and Marra 2013 Nature Communications; Graph: Bird mortality estimate (millions) versus estimate frequency] 

And just like this paper, I’m not going to go into all the details but we decided to first look at the impact of cats on birds in the United States. And we pulled together all the various sources, everything from the number of cats, number of owned cats that are outside, the statistics I already showed you, the number of un-owned cats that are outside, and how many animals they kill, how many birds, how many reptiles, how many mammals, how many amphibians. 

And there have been a variety of studies that have sort of qualified this over time. How many of these cats actually, for owned cats, how many of the prey items are they really bringing back? Because a lot of those data are based upon kills that are brought to your doorstep, and so how many things are their cats actually hiding? And so there’s really good studies using video or cat cams that show you that cats are actually bringing back a third of what they kill.

And so we basically built a model that allowed us to assess what the overall mortality was of birds across the United States. And we used really conservative estimates to get our lower lower number, but our median was 2.4 billion birds per year and our range was 1.3 billion to 4 billion. 

That 1.3 billion that, that low estimate, if that’s what you want to believe, that’s fine. I mean, I I tend to be much more conservative. That’s based upon 30 million cats in the U.S. That is the lowest number possible, that’s a very low number of cats in the U.S., 30 million. And we don’t, most estimates are around 60 to 100 million. To give you an idea of the level of conservatism that we’ve, that we use in this in this analysis. 

[Slide text: Mortality of other wildlife taxa?; Graph: Mortality (millions) versus estimate frequency with a median 12.3 billion for mammals, 173 million amphibians, and 478 million reptiles] 

But we also estimated mammals, 12.3 billion. Cats obviously take a lot more mammals than they do birds. 47, 478 million reptiles, and 173 million amphibians. Cats are opportunistic predators. They just they, and they don’t always kill to eat. They are they are doing, they’re just you know following their instincts. 

[Slide text: Direct Bird Mortality in the United States; Bar chart: Causes of bird mortality, with cats killing more birds than any other cause] 

So going back to this overall analysis, there’s two things I want to point out to you into this in this in this graph. Prior to our study, the study in 1970 and what the what the literature had always been saying is that cats are not the greatest cause of direct anthropogenic mortality, it was buildings. And these were estimates from Canada, and estimates in the U.S. Everyone thought it was buildings that were the primary driver. 

But at the same time we were doing our analyses, Canada was doing the same exact thing, totally independently from us. And what’s interesting here is that our analyses now show that cats are now by far, by almost four orders of magnitude, the largest cause of direct more, bird mortality in the United States, relative to buildings and windows, which is now at about 599 million. 

In Canada the same flip happened. Being at different sorts of analyses. Cats are now the largest cause of direct bird mortality in Canada as well, which is also provides another level of validation in our mind of the importance or the magnitude of mortality of cats. 

But there’s issues here. We don’t have species-level information, this is just bird, generic bird. There’s very little species-level information available. This tells me that in terms of priority setting, I should be doing something to sort of think about this cat issue, given the number of extinctions, given given the magnitude of mortality here. There’s some, there’s some issue happening here that we need to be, we need to be looking at in a much more significant way.

[Slide text: Are cats having population-level impacts? Photos: Cats with various wild animals they caught] 

So the bar that’s been set for cats as to whether or not we really tolerate them on the environment or not is this idea that are cats having a population-level impact? That is is the impact additive, or is it compensatory? That is that, can birds just respond and their population will go back back up?

And so I I think that this is an incredibly difficult thing to quantify, especially when the the population-level impact that people want to see is across an entire species range. Say something like the ovenbird. Are we seeing that decline across an entire species that’s attributable to cats? 

The level of information that’s required to get at that is impossible. We cannot look at and quantify all sources of mortality throughout the annual cycle for something like a migratory bird to really be able to assign this back to cats. Or buildings, or pet, it’s a very hard thing to do. We just don’t have the level of information to be able to do that. So it’s, frankly it’s the wrong bar to set. 

That being said, we can do local scale studies to bet look at population level impacts of cats. And they’ve been not surprisingly quite a few local scale studies looking at population level impacts of cats. 

[Slide text: (Crooks and Soule 1999); Photo: Coyote with a cat in its mouth] 

One of my favorite studies is one by Kevin Crooks and Michael Soule that looks at cats and interactions with other wildlife in Southern California, in the San Diego area. And what Kevin and Michael did was they looked at a series of fragments that varied in size. This is a coyote with a cat, preying on a cat. Turns out coyotes really like cats. Not in the way that we like cats.

And so they looked at a series of fragments that varied in in size, and were surrounded by a variety of houses that that, where people actually had cats that, and let them outside. And what they found was that in the large fragments, large fragments could support coyotes. The small fragments could not support coyotes. 

So in the large fragments where there were coyotes there were no cats, because the coyotes were eating the cats. And so and that was demonstrated really nicely by by Kevin Crooks and Soule through looking at fecal analyses and a variety of things. 

In those larger fragments were, where the coyotes were eating the cats, bird populations went way up. Those bird populations were really high because they remove the mesopr—, coyotes remove the mesopredators. In the smaller fragments where cat populations were really high the bird populations were crashing, were just totally crashing. And I’m just giving you sort of the back of the envelope description, but this is a paper that was actually published in Nature several years ago. It’s a fantastic, a fantastic paper. 

[Slide text: House Sparrows -60% decline (Churcher and Lawton 1987); Photos: House sparrows] 

Another study I’ll mention, again these are just two studies, comes from the U.K. In the U.K. of course house sparrows are native, they’ve been experiencing a sixty percent decline over the last 30 or 40 years. And what’s interesting in in the U.K. is that there there is a tremendous house cat issue, but they’re mostly owned cats that are let outside. 

People just really feel like they’re cats, in order for them to have an, a rich life they need to be able to go outside regardless of what they do. Even though, there have been studies that have shown what an individual person’s cat does; and they say I don’t care, I want my cat to go outside.

So this study, this was a study done in a small village in the U.K. where they tracked 70 cats and they quantified all prey items throughout the year, that all these cats were brought in. And they really did a wonderful job of tracking all mortality.

And what they were able to to say was that cats caused, again cats, non-native invasive species, were causing 30 to 50 percent of the mortality, direct predation on house sparrows. 30 to 50 percent of the mortality of that house sparrow population. 

And the population was was declining. So the authors concluded, just like in the other study in Nature that the mortality imposed by cats was indeed additive, and it was contributing to the overall decline of these species. 

[Slide text: Consequences; Photo: A human eye with an ocular toxoplasmosis scar] 

So the evidence that free-ranging cats are having a significant impact on the number of wildlife species, that they’re causing extinctions. The number of animals they’re killing every year is quite significant, it’s large. And they’re clearly having population impacts at the local scale. 

This scales up to bigger scales, right. Mainlands are not islands, but when you actually consider how much we’ve carved up the United States and other places of the earth, we’ve created artificial islands. And the impacts that happen in those things are island-like in many ways. 

So collectively the impacts of cats on biodiversity I think is quite convincing, and as I was pulling all this information together I just like shaking my head. It’s like I can’t believe we’re still in this situation now we’re in with cats.

But it doesn’t stop there, unfortunately. There’s more. This is a human eyeball, and that’s a ocular toxoplasmosis scar. It’s a human eye. It’s just one of the things that’s linked to Toxoplasma gondii. 

[Slide text: Toxoplasma; Image: Lifecycle of Toxoplasma with stages in cats; sheep, pigs, and rats; and humans] 

Let me explain. So Toxoplasma gondii is a fascinating manipulative pathogen. It’s a protozoan pathogen. Most people are aware of Toxoplasma, Toxoplasma and toxoplasmosis risk due to pregnancy. So when you’re pregnant, women are pregnant, they’re told not to change kitty litter boxes because of the risk of picking up a Toxoplasma oocyst, right. If you pick up a Toxoplasma oocyst there’s a there’s a there’s a possibility you could have a miscarriage or there could be other complications with birth. This is actually quite common in other places around the world where education isn’t as good. 

We here in the United States have done a really good job of educating people about this, so it doesn’t happen very often. Although just two weeks ago in Seattle there was a case. 

So this is how most people think of Toxoplasma risk, Toxoplasma gondii risk, but let me tell you a little bit about Toxoplasma gondii. 

This fascinating, manipulative parasite, this pathogen. It breeds only in cats, so cats, not just domestic cats, but felids more generally. We don’t know how widespread it is, it’s felids more generally are the definitive host. 

So Toxoplasma gondii only sexually reproduces within cats, so it finishes its its its annual, its full life cycle in cats. Cats will go through an infective stage once, every once in a while where they start shedding these oocysts, which are sort of like microscopic eggs, imagine. But they’re called oocysts. And they’re shed out in the environment, they shed out tens of thousands if not millions of these oocysts for two, three weeks. It varies.

And these oocysts are some of the most indestructible things in nature. They survive for multiple years, they survive frozen soil, they survive survive marine environments. And that creates a problem because then they’re exposed to unintended hosts. The idea of this pathogen is that it will eventually get into things like small rodents, and small birds, and what’s really cool is this protozoan parasite changes the behavior of its host. 

So a small mouse that was once fearful of cats is now attracted to cat urine, which is really cool because then it’s easier for a cat to prey on that animal, and that pathogen can finish its lifecycle back in that cat host. And this has been demonstrated in really cool experiments by people like Robert Sapolsky, Jaroslav Flegr, and published in really wonderful, wonderful places. So this is a a solid, solid foundation of understanding about what’s going on with the pathogen. 

But the problem is, and this is a problem with a lot of emerging infectious diseases, is that once this oocyst is out in the environment, the environment is sort of polluted with oocysts. And when you’ve got 60 to 100 million cats out there, shedding these oocysts and these oocysts don’t go away, this builds up over years. 

And it creates problems. And it gets into our food systems. And it, cats like to defecate where? Sandboxes, gardens. And so through fecal-oral transmission, through getting into our meat supplies. And it’s found often in meat, and when you undercook meat it’s thought that that’s one primary way that it’s ingested.

Although it’s now thought that that’s not as important as just fecal-oral transmission now. It gets into humans, it causes other problems. I’ve already mentioned the miscarriage problem, but there are actually other more disturbing problem, equally disturbing problems. 

[Slide text: Toxoplasma gondii Infection and Self-directed Violence in Mothers, JAMA Psychiatry, 45,788 Danish women whose level of Toxoplasma antibodies was measured in connection with child birth between 1992 and 1995, Women with a T gondii infection are 2x more likely to commit suicide] 

This is a study that was done in Denmark looking at Toxoplasma gondii infection and self-directed violence in mothers. Pretty good sample size, forty-six thousand Danish women who had their levels of Toxoplasma gondii antibodies measured, and once you have antibodies like, unlike a lot of other things, you don’t clear Toxoplasma gondii, it’s not cleared. 

The oocysts move up into your brain and they encyst in your brain. Occasionally they drop down to your eye and they cause ocular toxoplasmosis. Next time you go to your eye doctor ask them how often they see ocular toxoplasmosis. They’re going to say it’s quite common.

Oftentimes the scars heal, sometimes they cause blindness. And it’s amazing when I give these talks, oftentimes people come up to me afterwards and they say actually I’m blind in this eye, or I’ve been diagnosed with Toxoplasma gondii, and I’m just gonna say I’m not a doctor, I’m not that kind of doctor. But it’s amazing how common it is when you start talking to people about about these things. 

But back to this one study. So forty-six thousand women, Danish women, whose level of Toxoplasma gondii antibodies were measured between 1992 and 1995. What they found was that women with Toxoplasma gondii infection were two times as likely to commit suicide as those that were negative. 

Now this is a correlation. And many of these studies are correlations, it’s very difficult to do experimental infections of Toxoplasma gondii with human subjects. It’s a difficult thing to do. It’s difficult to do other experiments in mice that replicate what goes on in humans. 

But it doesn’t stop there, unfortunately. Toxoplasma gondii has now been linked, and I’m not talking about two or three papers, I’m talking about 50, 60, 70 papers from around the world, that have now shown a significant link between Toxoplasma gondii and bipolar disorder, depression, schizophrenia, and suicide risk. The CDC now considers Toxoplasma gondii, and toxoplasmosis, as one of the most neglected infections from a group of five parasitic infections in the world. 

There is one scientist that I’ve been, I was studying. This guy by the name of Tory, and his colleague from, he’s from John’s, his colleague’s from Johns Hopkins. They’ve been studying the link between Toxoplasma gondii and schizophrenia for over 20 years. And I read his earlier papers 20 years ago, and I was like this guy’s, he’s made some incredible contributions to our understanding of this, but initially in his papers he said but don’t worry about cats, not a big deal. And he studied this more and more, and he actually reports now that if you have Toxoplasma gondii infection you’re three times as likely to develop schizophrenia compared to somebody who’s negative. 

But I asked him, I said so now 20 years later after after doing all of this research, what is your current stance on cats? And he said his current stance on cats, and this is in the book, is that if you have small children, I do not recommend you have outdoor cats because of the potential risk of them developing schizophrenia later in life. Now I want to emphasize at the same time that for most people this is not a problem. Most people remain asymptomatic. If you have a compromised immune system there are issues there. 

But we’re still, I mean there’s there’s there’s enough to know that there’s a problem here. Do we need more research here? Of course, no question. We need to continue doing research. But some scientists that have been studying this think it is as significant if not more significant than the impacts of malaria. Malaria which is mainly, most of the real negative impacts are in Africa. This is global. This is global. 

So twenty, about twenty-two percent of us in this room right now are infected with Toxoplasma gondii. About one-third of the world’s population is infected with Toxoplasma gondii. 

[Photo: Hawaiian monk seal on a beach] 

It doesn’t stop there, unfortunately. Because as I mentioned the environment is polluted with Toxoplasma gondii. And so there have been wonderful studies, and but depressing results, of showing that sea otters for example in California, most the mortality is due to toxoplasmosis, Toxoplasma infection, Toxoplasma infection. 

This is a Hawaiian monk seal. Just last, last fall and winter, two Hawaiian monk seals, a critically endangered species, died of toxoplasmosis gondii. 

[Slide text: Another black mark against domestic cats: They’re killing Hawaii’s rare monk seals] 

This article just came out in October, “Another black mark against domestic cats: They’re killing Hawaii’s rare monk seals.” Domestic cats are all over the place in Hawaii, in islands of Hawaii, all over the place.

And the list of animals that are impacted by toxoplasmosis goes on. Spinner dolphins, Hawaiian goose, crow, Hawaiian crow, red footed booty, booby. This, I mean the list goes on, there’s whales, the list goes on and on because these oocysts persist in marine environments just like in terrestrial environments. 

[Slide text: Solutions; Photo: Catio, a screened porch area with places for cats to sit and play] 

All right, so we focused on the consequences. In my opinion they’re pretty significant. What about the solutions? 

[Slide text: Op-Ed When will people learn to treat cats like dogs?; Photo: Cat walking across a street] 

Well, one of the things I like to start off with is that when I was growing up, and before the time I was growing up, dogs would roam free all around my neighborhood. People would open the door, let the dog out, there there were un-owned dogs too, that would roam around in packs. People would occasionally get bit, rabies was an issue. We got it, it wasn’t good for the dogs. Dogs would get hit by cars. It wasn’t good for the dogs, right. We learned this lesson.

When will people learn to treat cats like dogs? Why is it okay for dog, for cats just to roam free? It doesn’t seem like the most responsible way to care for a domesticated animal to me, not to mention the facts, you know what they’re doing to other things. 

So we got that under control, in fact we ran on Op-Ed, I’ve got copies of the Op-Ed here that came out in the L.A. Times a month or so ago. In fact that, the day of that Op-Ed came out 

[Photos: Cat on a leash in an outdoor dining area] 

it’s kind of funny, my wife and I were at a local watering hole, bar celebrating our 18th wedding anniversary, and the waitress comes up to the table and she says I’m a crazy cat lady. And I’m like, what? I didn’t ask, I didn’t say a thing, but that very day that Op-Ed came out, and I said so I hope, I’m, great, I’m glad you’re a crazy cat lady, I’m glad you like cats, didn’t know anything about me. I said I hope you keep your cats inside. And she said, yeah, I definitely do. My two previous cats are, one was killed by a coyote, and the other one was killed by dog. I’ve learned my lesson. I’m not going to let my cats out anymore. 

And so she gave me pictures of her cat Mustachio, AKA Moose, and Moose, she’s actually trained Moose to be on a leash. And Moose now stops at the curb, goes across the street. Now not all cats can be trained on a leash, you’re not going to be able to take your cat for a run probably. So it’s not really an aerobic thing, but I’m seeing more and more cats on leashes. 

I’m seeing more and more people that feel like I need to enrich my cat’s life, but I don’t want to do it at the expense of other things. And so they walk their cats on leashes. This is for owned cats. 

[Photo: A cat in a catio] 

In cot, in Portland, in Oregon they’ve started to really push this idea of these things called catios. 


Lots of people in Oregon have catios. It’s great, they actually have catio tours, so you get a glass of wine, you go check out this catio, you go to that catio. It’s actually wonderful because if you really feel like your cat wants to have an enrichment, just get an enriched experience of being outside, seeing seeing wildlife, it’s fantastic. It’s doable. And it’s great for owned cats for people that really feel like their cat can go outside. 

But we need to do more. This isn’t enough. And I hope the trend is changing, that people that own cats are starting to keep their cats inside. But I, where I live in Maryland I still have enormous numbers of people who just let the cats outside because they feel like that’s the thing to do, that’s what they’ve got to do. 

But I really feel like we need to start requiring licensing. We do not require cat licensing, I don’t know of anywhere in the United States where licenses are required. That’s ridiculous. We need to step up enforcement. We need to fine people who let their cats outside. This is, we we did this with dogs, we’ve got to take the same path towards cats. 

[Slide text: How to deal with the remaining cats?; Photo: Four cats sitting on rocks near the ocean] 

But what about the un-owned cats? The outdoor cats, the 60 to 100 million, or even the 30 million, whatever the number is, what about those? This is where it gets really, really tricky and it’s a very, a very difficult situation. 

[Photo: Cat outside at night] 

There’s an enormous problem here. And what we’re doing, folks, is not working. For wildlife, for people, or for the cats themselves. It’s it’s just not working, and this is what’s, what I’m about to really get into is what’s really fueling the cat wars. 

There are few things that we can do, and but our main goal is really to reduce the number of cats. And the first two things that I’ll emphasize is something that most groups on both sides of the warring parties agree upon. 

The first is spaying and neutering as many cats as possible. And there’s enormous numbers of really, really dedicated people out there that are vets, and other dedicated almost citizen scientists, volunteers that spend enormous amounts of time capturing cats, neutering cats, spaying cats. That’s, they take their weekends and devote enormous amounts of resources towards getting as many animals spayed as possible, and neutered as possible. And it’s, and that’s fantastic. 

But it’s, unfortunately, it’s it’s it’s not enough. And I’ll explain why in just a moment. We have to keep doing it, and I think most owned cats are now spayed and neutered almost immediately. But it’s these un-owned cats that are the problem. 

Second, the second big problem is stopping pet abandonment. Most people think pet abandonment, really? Who would just abandon an animal? Well you’d be amazed at how many people abandon animals. When I’ve given these talks around the country this year, this, in the past few months people that are TNR colony caretakers come up to me afterwards, or they’ll they’ll ask me questions from the audience, and say you’re right, it’s it’s amazing how many people dump their cats. 

We don’t value cats like we value dogs. If you’re outside and you see a cat roaming around you’re not likely to do anything. You’ll probably think about it, maybe think of what it’s doing or whatever, but if you see a dog you’re going to do a second glance. You’re gonna think you know, wow. You might even you know stop and change your plans to catch that dog and see if it needs help. We don’t do that with cat, we don’t value, don’t value cats. 

But we need to do more to sort of solve this problem of pet abandonment. It happens at university campuses, happens at military bases, happens all over the place, it really does. But we need billboards. It’s a marketing problem in many ways, but it’s also an enforcement, enforcement problem. 

[Slide text: Trap Neuter Return (TNR)- Weak empirical support -Inhumane to leave cats outside -Neuter rates must exceed >75% -Immigration continues into colony- Encourages cat dumping -It’s not scratching the surface; Photos: Cats gathered in groups outside] 

So the one approach that has been aggressively promoted for at least the last 30, 40, or not 50 years is something called Trap Neuter and Return. And the idea behind Trap Neuter Return is that you trap the cats, you neuter the cats, so you stop reproduction, and you put them back out. 

And you feed them there, you have somebody that feeds them in a colony, in a colony setting. And by, by neutering them, spaying and neutering them, and putting them back back out ultimately the cat col, that colony of cats will go extinct. It will go away because they can’t reproduce ,and they’ll die of so-called natural causes. 

The problem is, there are several problems with this this whole idea, is that when you look at the data out there to see how many of these cat colonies actually go extinct, there’s weak empirical support. There really is not a lot of support that this works. 

[Slide text: Trap Neuter Return (TNR)- 155 cats 1991-2002 (11 years) -73 adopted out (47%) -17 euthanized -10 found dead (6 killed by cars, 4?) -32 were lost (??) -23 remained after 11 years, Levy et al. 2003; Images: 12 cats] 

I’m going to show you, walk you through one of the primary examples of a study that’s is supposedly an example, a positive example of where it, where it works. Um it’s an 11-year study, all right, so cats roam the landscape in this area for 11 years. The colony started with 155 cats, and the study went from 1991 to 2002, and so if you couldn’t tell I mean already the fact that the cats are out there for 11 years bothers me, right, so you’re leaving the cats out there, that’s an issue. 

73 were immediately adopted, which is fantastic. That’s 70, forty-seven percent were immediately adopted. But that’s not a test of Trap Neuter Return, that’s a test of Trap Neuter Adopt. And that success, very successful, but that’s not, that’s not a test of TNR. 

17 were immediately euthanized, that’s because they were diseased, or they had, they may have had HIV or whatever it was. They were euthanized, which was definitely a great thing to, important thing to do. 

Ten were found dead over that 11-year period, six of those were killed by cars, four it’s not clear what happened to them, they were just found dead. 32 were lost, 32 disappeared. They could have gone and established colonies elsewhere, they who knows what they did. Again, 32 were lost, I don’t know what that means. 

23 remained after 11 years. This is not a success story to me, but this is raised, this is held up as a success story in the TNR world. 

I would also argue it’s inhumane to leave cats outside. Cats when they’re outside don’t really know how to avoid cars, avoid predators like coyotes. 

[Slide text: It’s inhumane to cats; Photos: Dead and injured outdoor cats, including one hit by a car, several diseased, and one taken by an owl] 

In fact many people, including People for the Ethical Treatment of Animals, PETA, a group that I don’t normally associate with, myself with, is fully behind what I’m arguing for here. They are totally against TNR because of these horrible pictures on the screen. But this is reality. 

Just this week, how many people saw the red-tailed hawk with the cat in its claws? Not that many. Anyway, if you want to see a horrible video, there’s a video that somebody in St. Louis, some guy videotaped a red-tailed hawk capturing or, grabbed a kitten and it was just holding that kitten in its clutches, just like it would with a native prey item. And then it flew off with it.

That happens more times than you might want to know. This is the natural mortality that happens in the TNR colony. I’m not sure how this is a better end than the alternative. 

So the other problem with TNR is that in order for you to see population decline, you need to have at least seventy-five percent, but more likely upwards of ninety percent of the cats neutered or spayed in that colony in order for there to be no population growth. It’s very hard to capture that many cats and neuter them, especially given that most of these populations are open populations. That means there’s constant immigration into these colonies. And you have new individuals coming all the time. 

And these are not professionally managed colonies. These are colonies that dedicated, passionate people are managing, and trying to capture the cats in, trying to feed the cats in. They can’t do it all the time. So what’s happening is it’s creating this this larger issue. 

Immigration continues in the colony, and it also encourages cat dumping. Because people that don’t or can’t keep their cat anymore are more likely to dump their cats there. 

This happens all the time, and I have other TNR people tell me the same thing, that this is actually, they see this happening. They don’t realize that makes me more, you know um convinced that my stance is correct than I was before, but it’s totally true. 

The other thing folks is that across the U.S. we don’t even come close to spaying or neutering a million outdoor un-owned cats. If there’s a minimum of 30 million cats out there, and we’re barely even coming close to a million, we just nibbling, we’re just nibbling around the edges. We’re not, we’re barely scratching the surface of what’s happening here. We need a different solution. What we’re doing is not working, right. 

So finally, how are we evaluating TNR? These animals are still impacting biodiversity. So from the cat’s perspective they’re staying alive, but they’re still impacting so many other things. They still have the potential for spreading disease, and not just toxoplasmosis. 

Rabies is another issue that I haven’t gone into. I do in the book, I’m not going to tell you any more about it, you’ve got to read the book. But rabies is another issue, as are a whole other suite of diseases, right. 

And so we’re not, when we evaluate something like just TNR it’s not just from the cat’s perspective, we need to look at the holistic picture here. Especially when it’s environmental, and especially when it impacts so many things. It can’t just be from the cat’s perspective. 

[Slide text: Low Priority Conservation Areas 1. Confirm low impact 2. Ensure maximum sterilization and vaccination 3. Regular and proper census methodology; Photo: Cats eating outside in the snow near small shelters] 

So all that being said, we’re not going to get all the cats off the landscape immediately. It’s it’s just not going to happen. So in my opinion, and as I describe in the book we really need to focus initially on high priority areas. I would argue that TNR colonies, despite what I just told you, TNR colonies are lower priority areas, low conservation areas, areas of low risk of disease transmission, might have to persist. 

But if they do, we need to manage them properly. If we’re going to allow them to persist they need to be managed properly. Those animals need to be collared, they need to be microchipped, they need to be, their their numbers need to be measured properly, they need to be sterilized and vaccinated regularly. Often times they are when they’re first spayed and neutered, but they often need to get boosters in order for those vaccinations to actually be effective. 

It can’t just be neutering the cat and putting them out less than 24 hours back in the back in the wild. That’s not a good thing. If we’re going to do it we’ve got to do it properly. That’s not what’s currently happening. 

[Slide text: High Priority Conservation Areas; Photo: Camera trap image of a cat in a forest] 

So what we really need to figure out is where are these cat colonies that overlap with high priority biodiversity areas? Or areas where disease transmission is a problem, like elementary schools, for example which actually is quite common. It happens, I’m not sure it’s quite common, but there’s always, there’s lots of lots of situations where TNR colonies are placed at elementary schools, which is a big issue. 

And so high priority, all of Hawaii for example. Every state has high priority conservation areas where cats exist. Jones Beach, Cape May, New Jersey, Key Largo, Key West, Florida, Hawaii. Every state has these areas where they’re also TNR colonies, and it’s a battle, there are lawyers in each of these situations, with the desire to allow these cats to persist in these situations. 

We can’t. There has to be, in my opinion, there has to be a zero tolerance. And what does that mean? Well, we have to deal with these situations as humanely as possible. 

[Photo: Woman holding a cat on her shoulder] 

Like we showed in that study earlier, if we can capture them and adopt as many of these cats out as possible, that’s fantastic. But unfortunately, when these cats are in the wild for any length of time, they are not, like it’s very hard to get them to the point where they can actually be put into a home again. They are wild. They cannot be put into a home. It’s a problem. 

[Image: The Cat House on the Kings webpage describing their mission and special plea for help, with photos of lots of cats both inside and out] 

There are things like Cat House on the, Cat House on the Kings, where they’re basically cat sanctuaries where you can keep 750 to a thousand cats. There’s more of these around than you might, you might know. But these are enclosed areas where hopefully they are minimal, minimal impact. 

But again, with 30 to 60 to a hundred million cats out there, if we were to do that with all the cats we would have to fence in the entire state of Rhode Island, and I don’t know about you but I don’t think the good people of Rhode Island would be willing to to sort of give up their fair state for a lot of cats. And I guess I could make a Trump wall joke, but I won’t. 


[Slide text: Euthanasia] 

That leaves us with, really with one alternative. That we really need to address this problem with the sad reality of of euthanasia. And sometimes there’s really no better solution than euthanasia. It happens all the time right now in the U.S. with cats probably not to the degree it needs to obviously. And we’re not suggesting this for all cats. I’m not suggesting that we eradicate all cats across the United States, not doing that at all. 

But in terms of re-abandoning cats out into the, into the environment. Putting them back out in the environment. A lot of vets would argue euthanasia is definitely a better alternative than putting these cats back out into the environment. Some vets would not. But a lot of vets that I know, and I work at the National Zoo, and I work with vets all the time that are faced with this question of euthanasia all the time. And the sit, and the conditions that animals are under, many vets do believe that this is a much better alternative. 

[Photos: People pushing each other at a protest and cover of Cat Wars: The Devastating Consequences of a Cuddly Killer by Peter P. Marra and Chris Santella] 

So we are left with this ecological and animal welfare dilemma, and it’s turned into a war. The war has been going on for 20, 30 years. You publish one paper on science, it’s attacked. And again, the war is not between cats and wildlife, the war is really between people. And the constant refutations of the science that are demonstrating that cats are a problem. People that just feel really passionately about cats, and they don’t want to believe the the science.

There’s an anti-information war going on in more places than just politics. And it’s largely because it deals with this problem of ultimately needing to kill one animal to protect another. And this is a dilemma, it is an issue that we need to grapple with. 

But we manage, it’s, we manage wildlife, we manage environments in many, many ways now. We have to. We’ve we’ve manipulated and changed our our natural existence in so many ways, whether it’s, whether it’s dealing with getting rid of trees in in an area that’s of high burn potential, like in Tennessee. You know, if they’d burned those forests properly we may not have been looking at the forest fires that are taking place there, or in so many other places across the United States. 

And the list goes on. White-tailed deer, same thing, cats, same thing. But it is it is a problem.

[Photo: Cover of Cat Wars: The Devastating Consequences of a Cuddly Killer by Peter P. Marra and Chris Santella] 

So we don’t think that many people actually recognize this problem, but we’ve done plenty of science at this point to make the decisions that we need to make. Yes, we need more science. Sure there’s certain things that we can we can still figure it out. But but we know enough now that we really need to make these that make the difficult decisions moving forward. 

It took about 50 years to finally move the needle for climate change, for for people to finally stop refuting the science. It took about 20 years for DDT before we finally stepped in and and made the difficult choices. 40 years or so with lead. With cats, believe it or not there are papers going back a hundred years, to the turn of the 19th century, where people were talking about, late 1800s, early 1900s talking about the impacts of cats on populations. 

So we’ve known for a long time. We really need to move, you know, beyond the wars to the decision makers to make these difficult decisions, and act on the information that’s available, that we have in hand. And really do what’s right for wildlife, for human health, and I would argue also for the cat’s themselves. Thanks very much. 

[Applause] Any questions? 

[Audience question] 

[Pete] Yeah, so the question, yeah, you’re welcome to.


The the question was how do you tell the difference between, in outdoor cats, a wild cat and a feral cat? And so the main difference is that a feral cat has no dependence on humans whatsoever, so it’s, you’re out in a wilderness area, all of a sudden you see a cat running by. That or that picture of that that cat I had in Panama actually in this really remote area forest. That’s truly a feral cat. 

Outdoor cats that are un-owned can be wild cats, they may not, they may not acclimate at all to humans, if you ever walk by a 

[Audience question]

So all domestic cats have been domest—there are European wild cats that are native species. Oh I see. So yeah, morphological things, and the body types of those cats that are very different, and then genetically they’re quite different as well, yeah. Apparently, I don’t know how viable their young are but they do try to interbreed and it causes problems. In in some cases actually they do, they do have viable young. 

No no no there, no there are no wild cats in the United States. That’s right, domesticated cats.

Yeah, question in the back. 

[Audience question] 

[Pete] Yeah, yeah so the the comment was, could you comment on what’s going on in Australia with outdoor wild cats. So so the Minister of the Environment or I’m not sure the exact title, last year was convinced by the data and said we need to do a cat cull. 

And so they are, they’ve set a goal of euthanizing two million cats in various wild places throughout throughout Australia because of the impacts that these cats are having on some pretty remarkable species. The consequences there are, you know, they’re causing extinctions. They have caused extinctions. And they’re continuing to threat, threaten enormous numbers of other small mammals and birds in Australia. 

So they’re, and New Zealand is saying the same thing. And they’re both saying, you know, by 2050 I think New Zealand said, we’re going to be getting rid of all cats. Australia, I forget to know, the year that they gave, but they’re saying the same thing. No cats. The, other places have recognized this problem, and they’d move beyond this. And there was a backlash there. Celebrities came out against that that that that call, but the Australian Government has really stuck to it and they’re continuing to pursue that. Yeah? 

[Audience question] 

[Pete] Yeah. Yeah, yeah this is a very good question, the question is is when you get rid of the cats what’s going to happen with the rodents? For example, is there going to be a response and are rodent populations going to increase? And this is a common, this is a common question. 

We can’t control one problem with another problem. So that’s the other way to look at this, right. So we can’t use cats as a form of biocontrol. The way we need to deal with rodents is by controlling the sources of food, and the sources of water, and with rodenticides.

Cats actually don’t kill that many non-native species, we’ve looked at the diet. They do kill some rats. But what happens usually is that cat, rodents like Norway rats smell the cats and get their pheromones, and they disperse. It’s not direct mortality. There is some direct mortality, but a lot of it is just dispersal. So you’re pushing these rodents out into other areas.

Many of the other mammals that you’re referring to are actually native species, and so those native species need to be protected. So I actually am a big proponent of keeping a lot of those rodents even though they’re, they may be pests. They need to be managed in your house in other ways, not by not by letting cats outside. Yeah? 

[Audience question] 

[Pete] Yeah. Yeah. Yeah yeah. Yeah. It’s a really good question, and I really appreciate your story, and that’s really, really important. So the question, just the basic question was how do you fund this plan? How do we deal with this issue? 

And I would argue it’s a much bigger issue about how little we actually support shelters, and animal welfare, animal responsibility. I don’t think we do a very good job with it at all. And my hope is is that groups like the CDC will will start to get involved, USDA will start to get involved, government agencies will start to get involved. Through licensing there’ll be additional funds that are going to be supporting this, because you’re right, people aren’t going to support euthanasia efforts. 

All I know is that TNR is really not the solution. It’s a feel good solution for many people, and that’s why people donate to it because they love cats. But they don’t really have the same connection with wildlife and biodiversity. They don’t really understand the consequences of toxoplasmosis. That’s really why I wrote the book is to make sure people understood the collective impacts that’s that’s going on here. 

But the funding issue is a huge issue. Most shelters are not supported all that well. So again, my hope is is that this is going to be a, become a, my hope isn’t that it becomes a human health crisis, but my hope is is that agencies like the CDC will recognize this as a much more significant issue. And other groups like U.S. Fish and Wildlife Service will step up to the plate and start to take action in these areas where they really need to take action. Thankfully U.S. Fish and Wildlife does do these things, but they do it under cover. And they don’t make it public. 

And that’s a problem, and it puts people like you in vulnerable positions, in difficult situations.

In fact, in Key, in Key Largo where people are trying to get rid of cats to save a couple of rodents down there, there’s this gigantic colony in a marina right next door that keeps feeding cats into this colony. And it creates this huge problem because there’s this massive TNR colony right next to this to this big wildlife refuge, and there’s no enforcement. They can’t do anything about it. It continues to be a huge problem with an endangered species.

[Audience question] 

[Pete] The question is, and then I gotta go to somebody else, the question is how do you get access to private property to get the cats where the majority of cats are? And what I want to emphasize is this is a really complicated problem. The gen—, not that question in particular, the cat problem is a very complicated problem. 

There’s no simple solution here. That’s why we need to prioritize, that’s why we need to be strategic, and in my opinion we need to really identify those areas that, where cats overlap high priority conservation areas, like in Key West, like in Jones Beach, like in Hawaii. These are all on public lands and one of the first things that I would really like to see done is a statement that says no cats on public lands.

Once this starts, once people in more influential positions, decision makers step up and start making these statements I think there’ll be a tendency for others to come along with with those messages. Once we start stepping up and doing that. 

But it’s going to take, excuse me, it’s going to take that sort of, that sort of first step on public lands. It’s going to take groups like National Audubon Society to step up and say this is a problem, or the Royal Society for the Protection of Birds to step up and say this is a problem, because the evidence frankly is overwhelming. It is really clear. And so we need to have those really important and influential groups step up and say there’s an issue here, we need to do something. And then ultimately it will happen. 

But it’s not going to happen overnight. I don’t, I’m not kidding myself, Australia’s looking at 2050, right. New Zealand the same thing. We’re looking at a hundred years. And we’re never gonna get rid of cats, it’s not. I mean, outdoor un-owned cats. It’s never going to happen. 

What I’m concerned about right now are the birds of Hawaii, the stopover, the stopover of birds in Cape May, New Jersey, or Jones Beach, piping plovers in Jones Beach or other places. And again, there’s all sorts of places like this on public lands. Yes, the majority are on private lands, but there’s so many other areas that we need to be focusing on. If we can do that now, we’d be doing tremendous good. Yeah, thank you. 


[Audience question] 

[Pete] Yeah I, I, I’m going to interrupt for a second here. So I totally disagree with you

[Audience question] 

and yeah. I certain, so I mean 

[Audience question] 

I’m sorry. I’m sorry, but I disagree with you. The paper, for example, the paper that you’re referring to where we scale up. We, we threw out studies that were way too high, way too low, we, we only included studies that had a minimum sample size, it’s a collection of studies it’s not meta-analysis, it’s called a synthetic review. 

And we were very, very conservative in the papers that we included. We weren’t biased towards high or biased towards low. We had, we tried to get certain sample size, minimum sample sizes. So we included, we were very conservative in the inclusion of that model. Let me finish, no no no no no, let me finish. 

And so in this case it was, we were actually, I don’t agree that it was biased. We took the best available data, and that’s what you do you try to scale up to try to understand the impacts. 

[Amanda] So, in the interest, ma’am, excuse me there are a number of people that are here tonight, and that also online who also want to have the opportunity to ask questions. This isn’t really a forum for a lot of, we appreciate your comments, you’ve been given a lot of time, but it’s time that we take someone else’s question. But thank you. Pete will be around after, and I’m sure he’ll be happy to discuss. 

[Pete] Sure, yeah. Are we taking some questions online? Okay, okay. 



[Audience question] 

[Pete] It depends, it’s it’s going to be a site specific problem. It turns out a lot of the the baiting and poison approaches they’re using in Australia are not working that well. So they’re trying to, they’re developing a variety of other techniques. Cats do not actually eat dead animals very well, very well, they kill them themselves. And so poisoning cats is not a very, it’s a very hard thing to do.

So in this case it’s going to be a, it’s going to be a difficult thing to sort of say there’s one size fits all. It’s going to be like, in Hawaii it’s going to be a very different thing that it might be in a, in Jones Beach or something. Could be just capturing and then and then a euthanizing sort of a thing, as opposed to not capturing the animal and applying some other sort of a killing approach. 


[Audience question] 

[Pete] So the question is if we can’t already capture enough cats to spay and euthanize them, how can we already, how can we really do something that makes a difference? Again it’s got to be a targeted approach. 

So if you’ve got an area like Jones Beach, or Key Largo, Florida, or Cape May, New Jersey, or again areas in Hawaii where they are posing an extreme risk, you can go into those specific areas and you can remove those cats. 

We’ve done it before. We’ve done it in other areas. We just don’t do it because of the current problem. But people have done it, and you know what? When you remove the cats, birds come back. And so, you know, they really are having impact, the evidence is really clear. 

And birds come back when you remove, when you remove the threat. That’s the exciting news here, and it’s the reason I’m optimistic is that nature is resilient and we can solve these problems. And the cat problem should be the low-hanging fruit. 


[Audience question] 

[Pete] Yeah.

[Audience question] 

[Pete] I am, yeah. I totally, yeah. 


No, I to. So the question is is that euthanizing animals is a very, very difficult thing to do. And there’s something called compassion fatigue in veterinarians. And that veterinarians that have toxoplasmosis are four times as likely? Veterinarians period are four times more likely to commit suicide. Yeah, and so how how, who is going to do the euthanizing? And, you know, I agree entirely. This is a problem, I, and I I don’t have solutions to everything here. 

And I’m not sure it’s just veterinarians that are going to be doing the euthanizing. It can be wildlife control officers, or can be a variety of things. I’m not sure we’ve worked out the situation. All I know is we’ve got a problem, we’ve got a problem. And we’ve got to figure it out. And I just, I don’t have all the answers. 

And there may be some veterinarians that are just not going to be doing the euthanizing. And there’s some that that may. There’s some wildlife managers that may be willing to do this, and some that are not. And we need to figure that out. People that don’t want that job, don’t get that job. 

But, we’ve got, we can’t just close our eyes and let this persist. That’s that’s the point. And as a group we need to figure out how to solve that problem. And so again, I’m not, I’m not, I don’t have all the solutions. I totally hear you. And I totally agree. I work with a lot of veterinarians, I really do. And I talk about this issue from a variety of perspectives. And for the most part they’re in agreement, with the ones I talk to. I do know some that are not. But most are. 

One more question. Yeah? 

[Audience question] 

[Pete] Yeah. Yeah. You said with laws? Right, right. So the question is are we moving forward with a legal solution towards free-ranging cats or un-owned cats outside? And right now, no. 

There’s, I mean, there are towns that have these things, but because of the lack of funding for most of the shelters that are out there, and we just don’t have you know dog catchers like we used to in the form of cat catchers. 

It’s it’s we don’t have the same effort that’s being put into this into this issue. And so the legal, the legal means are actually going the other direction to try to legalize TNR, to try to get state funding for TNR, to make it legal in particular states or particular cities or other municipalities. To make that legal so those animals are protected. And it’s not really, we’re not being really successful in trying to enforce like leash laws, or licensing of of cats yet. 

But I’m actually going to be giving a talk at the Department of Justice in the next month or so to a lot of the people that think about this about this issue to move this forward at a federal level. 

[Amanda] Thank you, and thank you, Pete, for your talk, and thank you to the audience and to the viewers online. And I really appreciate people, I think we all do, of sharing the different concerns, because I think whatever side of the issue or whatever perspectives people bring, we can all see it’s coming from a place of genuine concern that people have. 

And it’s been really useful tonight to hear different kinds of concern, you know, we’re not going to be able to address the issue unless we really understand everyone’s perspective. So so thanks for sharing your thoughts and your questions, Pete’s going to be here afterwards, so you can talk with him.

[Pete] Signing books.

[Amanda] Signing books. You can purchase the book. And thank you again for coming.


[Pete] Thanks. There’s also copies of this Op-Ed if you’d like some.

End of transcript

Pete Marra, head of the Smithsonian Migratory Bird Center, talks about the threats free-ranging cats pose to biodiversity and public health throughout the world, and proposes possible solutions to this thorny problem. Marra’s new book, Cat Wars: The Devastating Consequences of a Cuddly Killer, covers mounting scientific evidence that in the U.S. alone, free-ranging cats are killing birds and other animals by the billions. For more information, see our FAQ page, Outdoor Cats And Their Effects On Birds.