WHAT MAMMALS DO YOU SHARE your backyard with? We’ve all read the headlines: coyotes in New York City and Chicago, and more human encounters with black bear. Sales of so-called trail cameras are up, and not just to hunters or scientists. Gardeners are just one segment of a growing population wanting to know what goes on outside, especially after dark. I asked Dr. Roland Kays, co-author of the field guide and app “Mammals of North America” how animals populations in our human environments are shifting—and why.
The backstory: When I heard the title of a lecture being given nearby by a visiting North Carolina State University zoologist, I had to know more. The talk wasn’t titled “Woodchuck-Proof Your Backyard,” or “Rabbits Be Gone,” which would have attracted me, too, but for more obvious reasons. It sounded far more dramatic:
“The Return of Predators to Urban America.”
The speaker was Kays, a North Carolina State University zoologist and expert in using new technologies to study free-ranging animals, including the ones that may very well live in your neighborhood and garden. He leads the project called eMammal—a citizen-science animal-counting collaboration with the Smithsonian—and directs the Biodiversity Lab in the Nature Research Center of North Carolina Museum of Natural Sciences. I invited him to my public-radio program to talk about all that, and more—including how some animal species use humans as a shield against predation, and how to learn the number of mammal species in your neck of the woods—or suburbia.
Read along as you listen to the July 6, 2015 edition of my public-radio show and podcast using the player below. You can subscribe to all future editions on iTunes or Stitcher (and browse my archive of podcasts here).
And enter at the bottom of the page to win a copy of Roland’s mammal field guide and app, from which I learned that 52 of America’s 462 mammal species share my Zip code–or 463, if you count me and my fellow humans.)
my q&a on mammals with dr. roland kays
Q. You have done field work in other areas of the world (and you ride a unicycle, to name a totally unrelated thing about you that made me smile). How did mammals closer to home get to be the focus–how is it that rather than kinkajous and ocelots, you’ve had your eye on raccoons and coyotes and such, around Raleigh-Durham, and now look to other such domestic settings for research?
A. I think the animals close to home were where it all started, and they’ve never gone away. That’s what got me interested in science and ecology and conservation right from the beginning. Growing up in Michigan and running around the wood in my backyard, and the stream down the street—just getting out there with the Boy Scouts and hiking and enjoying nature.
I’ve had the fortune to go check out people’s backyards in other parts of the country—not literally [laughter]—other ecosystems, other animals. But I’ve always had interest in local stuff as well. I worked at the New York State Museum for 11 years, in Albany, and did work on fishers and coyotes and other animals that were right in suburban Albany.
Now I’m in Raleigh and continuing that work there. [Below, new video of fox and coyote findings in suburban Raleigh.]
Q. We read a lot about habitat loss and other profound human influences forcing animal species either out of areas where they traditionally live, or even toward extinction. But some of your recent work (and your upcoming talk at Cary Institute) looks at the species who are trying to survive by responding to those same human impacts and evolving.
A. Habitat loss has been a huge problem around the world for a long time, and continues today in large parts of the world. But in a lot of the Eastern United States, a lot of the habitat came back. The low point for wildlife was about 100 years ago, where there were so few forests left, and there was no management of the hunting or fur trapping. There was hardly any forest, and people were setting traps and shooting things year round without any restrictions.
We’ve come a long way: the hunting and trapping is well-managed, and we have abundant game populations, and the forest is back all over the place. There is way more habitat now than there was 100 years ago. The animals are returning.
Evolution—the changes in animals—includes changes in their behavior, and I think what we’re seeing is that they’re starting to more and more into urban areas, and certainly suburban areas, and into the outskirts of town. They’re kind of reclaiming some of their old territory, but in different ways, because we’re here now.
Q. [Laughter.] We are.
A. They’re slotting in, in the spaces between all the human settlement.
Q. In a recent paper you wrote with a colleague, you wrote: “Backyard animals represent one of the closest and most permanent wildlife-human interactions.” But how do those interactions go, for the animals and for the humans?
A. Maybe the most amazing part is a little more subtle: which is how few of these interactions there are. So many of these animals are out at night, when we’re sleeping. There are so many animals we don’t even know are sneaking around, using the woods near our houses or coming into our backyards that we never see. There is a lot of that.
Certainly there are interactions as well—and most are positive. People like seeing the birds in their yard; they like for the most part seeing the animals.
They just don’t like the negative side: for gardeners, when the herbivores eat all the plants they’re trying to take care of. When that herbivore happens to be a giant bear, then it can start to be dangerous.
It does go up to the very extreme in some cases of carnivores actually attacking people, but usually when that happens it’s when an animal has rabies. It’s a freak occurrence; not very predictable and not very common. There is also the potential for healthy animals to attack, especially smaller people, like children.
That’s very rare, but looking at the total range of possibilities, it goes from being totally charmed by the beautiful buck walking through your backyard, to being terrified by some carnivore that’s maybe a threat to you or your kids. That’s the whole range of experience with nature anywhere in the world, and now they’re starting to extend themselves into our yards.
Q. How is it different when there are backyard chickens, for instance, or a fence or unfenced dog—some of the specific trappings of our human existence in these areas, and the animals who explore them. Some elements might be attractive and others repellent to the various mammals, I suspect. [Roland’s highlight reel of backyard chicken coop visitors, above.]
A. These are the types of questions we’re still learning the answers to, and it’s kind of a new area of research: to see why there are some animals in some places and not in other places, and what are the consequences of that?
We’ve done some work such as the project with the chicken coops, where we were interested if chicken coops attracted different types of animals to someone’s backyard than yards that didn’t have coops.
We worked with volunteers in the Raleigh area that did or did not have chicken coops, and they ran camera traps in their backyard or sometimes out in the woods nearby. These motion-sensitive cameras take a picture whenever a warm-blooded animal walks in front. They don’t sample turtles very well, or snakes, but they get mammals chipmunk size and up, and any bird that’s walking on the ground in front.
They take photographs of the animals, and then the volunteers identify the animals and send the data to us. We then sort of check it. We love it from a scientist’s point of view because we can verify the data. It’s not somebody telling me they think they saw a mountain lion in their backyard; it’s actually a photograph I can verify. This is a red fox, or this is a gray fox.
Q. You mean all the wolf sightings that you hear about? [Laughter.]
A. There is no ending of the mountain lion tales, and wolves sometimes as well. Mountain lions seem to be more on the line of Sasquatch.
What we found with the chicken coops was a little surprising, because there’s the story of the fox and the henhouse; the fox raiding the chicken coop. In Raleigh we have a lot of gray foxes, not as many red foxes.
Q. I do too; it’s a favorite animal.
A. So there was no effect of chicken coops on the likelihood of a gray fox being in your backyard. They were quite common in yards that had chicken coops, and yards that didn’t. We didn’t get any record of the gray fox showing any real interest in the chickens, which at night are all locked up and kept inside. We didn’t see any conflict.
Raccoons, on the other hand, were a problem for the chicken coops. They were more common in yards that had coops, and we got them trying to break in, climbing over the top, stealing eggs. It seems like in the Raleigh area, raccoons are the ones you need to keep out of your chicken coop—you need to raccoon-proof it, which is tricky because they are very good climbers. They’re not as good diggers as some other species, but they’re crafty. They know how to get into garbage cans; they’ll find a weakness in your chicken coop if they can, and cause some trouble.
The other interesting thing with the foxes was comparing backyards to small urban woodlots. The foxes were actually more common in the backyards; that was their preferred habitat.
Q. Interesting; I wonder if with mown areas they can find more rodents and such or what is going on.
A. Food is likely an option. Gray foxes eat a bit more fruit than other foxes, so it could be that some people had fruit trees, or they were sniffing some bird seeds, but we still have a lot to learn about urban gray fox ecology and behavior.
Q. And they can climb, yes?
A. They are about the only Canid—the only dog family relative—that climbs trees pretty regularly. That’s thought to help them get at the fruit they’re known to eat, and probably also helps them escape from coyotes. Coyotes are known to persecute smaller predators—chase them, kill them, kill their babies. The gray foxes seem to do better with coyotes, probably because they can scamper up trees if they get in trouble.
Q. You talked about camera traps, and people sending in data from their camera traps. Is this all part of eMammal? [Video about eMammal, above.]
A. The chicken coop was one of our first projects with eMammal, which is a citizen-science camera-trapping project. We have volunteers run cameras. They upload the data to us, and again they identify stuff and we double-check it and put it in a database and use it for all sorts of different questions.
Q. You’re expanding eMammal beyond Raleigh-Durham, yes?
A. We are. We have a bunch of cameras that we can loan out, mostly in the Raleigh-Durham area. This question of how far carnivores are moving into urban areas is what we’re trying to address here.
But if you have your own camera, you can participate. We’re working on a big revamp of our website this summer, so it will be a little easier in the future to see and compare what you found with what other people around the world are finding.
Q. Let’s talk about habituation–how some species seems to learn to live with us, or work around us. We’re warned with bear, for example, of things to avoid doing that might make them more interested in our backyards.
A. Habituation is animals realizing that humans are not a threat. Predation is the Number 1 thing animals are worried about. You mess up avoiding a predator once, and you’re dead. They’re very sensitive to that. But it’s also the kind of thing that can be fine-tuned over time.
Avoiding predators is costly. If you’re always looking around, or always hiding, then you’re not getting food. There is this balance between avoiding predators and getting food.
If a predator is not actually a risk, and you start to ignore it as a risk, then you can feed more, you can have more babies, you can be more successful. So this habituation is basically animals realizing that humans are not a threat to them and ignoring them.
If they see humans as a threat, as soon as they see you they’ll run away—or they’ll hear you or smell you coming and run away, so you never even see them. So from our side, what habituation means is we see the animals more often, and are able to get closer to them without their running away. You can kind of tell that an animal’s not on alert when they see you, if they’re ignoring you.
If they’re really concerned about you they will pay a lot of attention. Even if they don’t run away, they’ll be keeping a very close eye on you.
Q. Can habituation happen with all mammal species to some degree?
A. I think so. We tend to see it more with the herbivores: the deer, the squirrels for goodness sakes. The herbivores are the prey of everyone else—they’re paying the most attention to predators. One of the concepts that scientists find interesting and have started to explore, to see how important it is, is to see how species can habituate and basically use one species as a shield against another.
In this case, I’m talking about using humans as a shield against larger predators. Other predators like coyotes are usually pretty leery of people. So the herbivores—the deer and rabbits and squirrels—habituate to people. They realize, “Well, these people are a lot less of a threat to me than those coyotes out there in the woods are. I can come in and maybe I get chased by a dog once in awhile or have to hide from a person, but that’s a lot better than being out there in the woods where the coyotes are really a threat to me and my children.”
Of course I’m anthropomorphizing the brain of a herbivore here [laughter]. But that’s basically the process we think is going on: that evolution is selecting for animals that fear humans less, and so then move in a lot closer to humans to escape their main predators.
There are some reasons to think this habituation might happen faster in the prey than in the predators, but were starting to wonder how long before these predators start catching on that we’re not really a threat to them, either, and start moving more and more into the urban area.
That might be what we’re starting to see, for example, with the increasing sightings of coyotes around New York in the last year or two. [Coyotes caught on camera trap, below.]
Q: In your “Mammals of North America” field guide from Princeton University Press, I loved going through the maps to see sort of, “Have I met everyone yet who’s in my neighborhood?” I see there’s an app for it as well.
A. Yes, and the app is even better than the book for that, because it has what we call GPS-assisted identification. The phone will tell the app where you are, and it will show you only the species that overlap with your location. So if you find a mole in your backyard, you’re not trying to rule out moles from Alaska or California. You’re just looking at candidates of the ones that are actually available.
Another thing about the app is that it has the sounds of about 150 mammals, which are really fun to listen to.
Q. I thought I knew all the mammals around me, but who knew: lemming!
A. The Northern bog lemming. That’s the southern-most lemming species; it’s really hard to see. It was my nemesis mammal for a long time.
Q. So I don’t feel so bad.
A. I had tried to find one for a long time, running small traps in various projects, and we finally got one last year in the Smoky Mountains with my mammalogy class. They’re kind of like voles.
Q. I’ve gotten to where I can tell my voles apart—the Southern red-backed vole from the meadow vole, for instance—but I didn’t know there was a bog lemming here, too.
A. There is some theory that the bog lemming might use the less-productive grasslands, where the other species fall out, so they’re able to compete.
Q. Squirrels unhinge people, or delight people, or both—and I always wonder about the different colorations. We have a lot of black individuals among the gray squirrel species here. Do people ask you about squirrels a lot?
A. The coloration often fascinates people and they think they’re different species, but it’s just color morphs, as you said. There is some research suggesting that these black morphs do best in Northern cities, where the blackness gives them a little more warmth in the sun in the winter. But the lack of predators in the cities lets them survive despite not being very well camouflaged.
enter to win a copy of ‘mammals of north america’
I’VE BOUGHT an extra copy of Dr. Roland Kays’ book, “Mammals of North America,” and one of the app, too, to share with a lucky reader. All you have to do to enter is comment in the box at the very bottom of the page, past the last reader comment, answering this question:
How are the mammal interactions at your place going?
Me? In my rural location, surrounded by many thousands of acres of state park, someone is always making themselves known. On dewy mornings, one of the first things I do is look for footprints on the porches and stone patios (or in winter, for prints in the snow). The mammal who unhinges me is the Eastern cottontail, since it’s so impossible to get it to enter a cage trap, and the good (read: rabbit-free) years are the ones when a fox family decides to set up housekeeping inside my big fence.
No answer, or feeling shy? Say, “Count me in” or some such thing, but an answer’s even better. I’ll draw a random winner (U.S. or Canada only) after entries close after midnight Sunday, July 12, and will notify that person by email. Good luck to all.
prefer the podcast version of the show?
MY WEEKLY public-radio show, rated a “top-5 garden podcast” by “The Guardian” newspaper in the UK, began its seventh year in March 2016. In 2016, the show won three silver medals for excellence from the Garden Writers Association. It’s produced at Robin Hood Radio, the smallest NPR station in the nation. Listen locally in the Hudson Valley (NY)-Berkshires (MA)-Litchfield Hills (CT) Mondays at 8:30 AM Eastern, rerun at 8:30 Saturdays. Or play the July 6, 2015 show using the player near the top of this transcript. You can subscribe to all future editions on iTunes or Stitcher (and browse my archive of podcasts here).
(Photo credits: Thanks to Roland Kays for images and videos. Disclosure: Purchases from Amazon affiliate links yield a small commission.)