Michael Hawk owns copyright in and to all content in and transcripts of Nature’s Archive Podcast. 

You are welcome to share the below transcript (up to 500 words but not more) in media articles (e.g., The New York Times, LA Times, The Guardian), on your personal website, in a non-commercial article or blog post (e.g., Medium), and/or on a personal social media account for non-commercial purposes, provided that you include attribution to “Nature’s Archive Podcast” and link back to the podcast.naturesarchive.com URL.

Transcript creation is automated and subject to errors. No warranty of accuracy is implied or provided.

Transcripts are automatically created, and are about 95% accurate. Apologies for any errors.

[00:00:00] Michael Hawk: It’s hard to imagine a time without roads that connect us, facilitate commerce, allow us to reach hospital schools, family, and friends. And in plain sight, they grow in width, link density and traffic volume slowly and continually. Amidst to the sprawling network that shapes our lives. There’s a realm often overlooked, but equally profound. A, domain where the intersection between humanity and nature takes an unforeseen twist. Our guest today has Ben Goldfarb, .

[00:00:27] Author of the new book “Crossings: how road ecology is shaping the future of our planet”. You might remember Ben from a past episode where he discussed his book on beavers appropriately titled eager. And in typical Ben form, he reveals a hidden world in plain sight, full of surprises. From rapid adaptation by some animals

[00:00:45] to the intractable ways that 70 mile per hour traffic hack many animal’s ability to cope. Ben book will be released on September 12th. You can find more details at bengoldfarb.com or check out the show notes.

[00:00:58] So in the meantime get ready for a fascinating look at road ecology with Ben Goldfarb.

[00:01:04] Good morning, Ben. Welcome back to Nature’s Archive.

[00:01:07] Ben Goldfarb: Thanks a lot for having me, Michael.

[00:01:08] Michael Hawk: I, actually, you’re one of the few Nature’s Archive interviews that I will actually go back and listen to again. I hate to hear my voice that much. That’s the reason, but I think our previous discussion about beavers was just so interesting to me that I often refresh myself on some of your talking points.

[00:01:25] So I’m really looking forward to today’s discussion, an entirely new discussion relating to your new book.

[00:01:30] Ben Goldfarb: Yeah, well thanks for having me back, and I feel like you can’t get enough beaver content. I don’t blame you for returning to that conversation, because beavers are endlessly fascinating, and I hope that roads are too.

[00:01:42] Michael Hawk: Yeah, and roads are really getting a lot more play in media and especially in the ecological world. So I think this will be a fascinating conversation. Now I’m not going to repeat too much of the background that we spoke about in the first episode and rather I’ll recommend that listeners go back and listen to that and hear a little bit about you and how you got into environmental journalism in the first place.

[00:02:05] But let’s pick up there. As an environmental journalist, how do you pick your topics? You found some really good ones.

[00:02:13] Ben Goldfarb: Yeah, I hope that’s true. That’s a great question, Michael. I mean, I think some of it is serendipity, right? You meet the right people, and they’re incredibly charismatic and sort of persuade you of the, the worthiness of a certain topic. that’s what happened with beavers for me was meeting, this guy named Kent Woodruff, you know,the longtime director of the Methow Beaver Project in North Central Washington. This really charismatic beaver evangelist who, who sort of sold me on, beavers as this, wonderful topic, which certain they turn out to be.

[00:02:43] And I think, the same is, was true in the, in the world of, road ecology, you know. It was meeting and writing an article about this guy, Marcel Hauser, a Dutch road ecologist, , now living in Montana, , who’s, you know, really one of the leading researchers in the field, he was the one who kind of, gave me the red pill, as they say, and, brought me into the world of road ecology, almost exactly 10 years ago.

[00:03:04] Michael Hawk: How do you define road ecology?

[00:03:06] Ben Goldfarb: Yeah, I’m still working on that, and you know, I think that even some road ecologists are, are, you know, trying to, figure out exactly the tersest, best definition, but you know, I think that it’s, it’s sort of the sum total of the ways in which roads interact with and shape nature, and some of those effects are obvious, you know, road ecology is very concerned with roadkill, right?

[00:03:28] The carcass that you see lying on the side of the road, that’s kind of the most conspicuous, invisible way that road shaped nature, but you’ve also got the noise of traffic, which is really affecting animal distributions. You know, you have the road salt that’s applied as a de-icer that’s changing aquatic ecosystems.

[00:03:44] you have roads cutting off wildlife migrations, you know, so animals aren’t necessarily being killed by cars all the time. Sometimes the, kind of the moving fence of traffic is enough to deter them from reaching critical habitats. So, you know, you have this vast spectrum of different road ecological impacts, and, some are obvious and some I think are less so.

[00:04:05] Michael Hawk: Yeah, I’m looking forward to getting into both sides of that equation, the obvious and less obvious sides anyway. In your book, so we’re going to talk about your book Crossings, which – remind me of the official release date, and maybe this is actually just a point where you can pitch how people can get it.

[00:04:23] Ben Goldfarb: Sure, yeah, so the book is called Crossings: How Road Ecology is Shaping the Future of Our Planet. It’s out, on September 12th from W. W. Norton, and it’s, you know, available everywhere that, books are sold. Online retailers certainly, you know, I’d be honored if you, asked your local independent bookstore to shop it or requested it from the library.

[00:04:40] yeah, you can get it anywhere you can get a book.

[00:04:43] Sounds good. And I’ll, I’ll include a few links, to the publisher page and elsewhere to make that easy for people in the show notes. So in the process of researching this book, when did this idea first start to coalesce? Like, hey, there’s enough here that this would make an interesting book It really goes back a decade. So in 2013, I spent a few months driving around the northern Rockies, you know, Montana, Wyoming, British Columbia, Alberta, writing about wildlife conservation and habitat connectivity. this idea that we need sort of linked, connected habitats that animals can seamlessly move through to, you know, meet all of their sort of biological and ecological needs. And one of the projects that I had kind of caught wind of, in the course of this, reporting trip was a series of wildlife crossings, you know, an overpass and a bunch of underpasses for animals, along Highway 93 in northern Montana, on, on the Flathead Reservation, Confederated Salish and Kootenai tribal land.

[00:05:37] and I, sort of requested a tour of these structures from this guy, Marcel Hauser, who is with the Western Transportation Institute in Missoula, and it’s, really done a lot of the monitoring of these crossings to see whether they’re really reducing roadkill, to see what species are using them,

[00:05:52] and he took me on this day long tour of these wildlife crossings along Highway 93. you know, the tour took, we went to a bunch of different, wildlife underpasses. And then the final sort of stop on this tour was this big wildlife overpass, that’s used by elk and all kinds of other creatures.

[00:06:09] And so we, you know, Marcel opened the gate in the roadside fencing, we went up on top of this overpass as the sun was setting. It was just this incredibly beautiful, inspiring moment to be on this, remarkable piece of infrastructure that humans had built explicitly for wildlife, we obviously do so much on this planet to, you know, to make animals lives harder.

[00:06:33] And here was, you know, this kind of dramatic, way in which we were attempting to facilitate their movements rather than, you know, cut them off as we so often tend to do. so I was really captivated by that. I was also captivated by the kind of imaginative challenge of creating infrastructure for animals.

[00:06:51]

[00:06:51] Ben Goldfarb: Marcel talked a lot about the different habitat features that, you know, existed on this overpass and, and that should exist. things like visual screens to prevent animals from being deterred by headlights sweeping over the overpass, or, , little pockets of brush, you know, that might be planted to allow animals as small as meadow voles to hopscotch from, feature to feature.

[00:07:13] So I just, I just loved that, that notion, you know, how do you build, structures that appeal to an entire ecosystem, in a sense. Obviously every, species has its own sort of habitat requirements and, ecological niches and, how can you build infrastructure that checks all of those boxes for different species.

[00:07:32] So I, I loved, the imaginative challenge there. , from that, that evening, I think in, October, 2013. I was, I really felt like there’s a potentially a wonderful book, there. And, you know, beavers kind of intervened in my life for a few years and got me off the road ecology beat.

[00:07:48] but you know, as soon as the beaver book published in 2018, I knew the next project was going to be a book about road ecology.

[00:07:55] Michael Hawk: Yeah. So as you alluded to, road ecology is so much more than just roadkill that we often see. And in fact, in your book, you had mentioned that this topic has become an urgent topic in the world of ecology. Why is that?

[00:08:10] Ben Goldfarb: Yeah, I think it’s a combination of factors. I think that one factor is that we’ve learned a lot more over the last two to three decades about how important it is that animals be able to access the entirety of their habitat, , and different types of habitat as well. I think that obviously the notion of habitat connectivity, you know, the fact that , just like people, you know, animals need places to find food and mate and disperse to new territories.

[00:08:35] this notion of connectivity, and large landscape conservation. I think, you know, the scientific literature is just pointing us in that direction, that we need large intact landscapes, over which animals can move. And of course, roads are the structures that prevent animals from moving. I think that’s part of it, this growing scientific emphasis on, habitat connectivity.

[00:08:57] and then, you know, the other thing that makes it so urgent is that a lot more roads are being built, right? that’s true to some extent in the United States, but it’s especially true, internationally. in continents like Asia, Africa, South America, as well as Central America, new roads are, being created, all the time, frequently through remaining intact habitats, places that haven’t had a lot of infrastructural development historically, but are, experiencing it now.

[00:09:24] And, you know, certainly some of that infrastructure is important for human quality of life. , ,, just as, you know, you and I benefit from access to hospitals and schools and, markets, which roads facilitate, , certainly some amount of, of road development , is useful for human quality of life.

[00:09:40] but you know, it’s also important that that development doesn’t occur in really, uh, ecologically destructive ways. And that’s, what road ecology does. It points us towards ways to hopefully, help that development lie lighter on the land. So that’s a big part of why this topic is urgent as well.

[00:09:57] Michael Hawk: So hinting at some of the focus here of why it is an urgent topic. That again, the title of the book, you begin with Crossings. So can you tell me why you picked that in the context of connectivity?

[00:10:09] Ben Goldfarb: Yeah, I think, for a few different reasons. I liked the sort of the, you know, the multiple resonances of that word. I mean, first, of course, most obviously are wildlife crossings, right? Road ecology’s primary tool for allowing animals to safely cross, highways. there’s also the fact that, crossings also refers to the ways in which roads cross the land.

[00:10:30] the fact that our, our continent is crisscrossed by, , this infrastructure for human convenience. And there’s the fact that, our journeys as humans are constantly crossing the journeys of wild animals. we’re sort of moving forever. at right angles with each other, you know, in these perpendicular vectors, you know, they’re crossing the highway and just as we’re driving down it and, we cross paths often, fatally for, for them. so I, I just liked, I liked that, kind of the multivalent resonance of that, that word crossings.

[00:10:59] Michael Hawk: Yeah, and the thing that kind of stood out to me is, in a way we’re at a bit of a crossroads in our relationship with roads and infrastructure, too. So, that’s a crossing of sort, too.

[00:11:11] Ben Goldfarb: Yeah. I hadn’t thought of that, but you’re, you’re absolutely right. You know, I think that roads, , this topic that was sort of long neglected, by, conservation, unfortunately, is increasingly in, in the zeitgeist, that’s kind of the, one of the ironies of, of roads, you know, that I, I try to get at in the, book is that, they’re such a fundamental, ubiquitous part of our daily lives that we almost don’t see them anymore, we just use them constantly and, kind of ignore them, As a result, I think we’ve, , for at least many of us, have failed to fully account for the ways in which they transform and, and, harm nature because we simply don’t notice them.

[00:11:45] But I think that we’re at a crossroads, as you say, in the sense that we’re increasingly becoming aware of how ecologically destructive they are and how important it is that we mitigate them somehow.

[00:11:55] Michael Hawk: And certainly we definitely take roads for granted. I, I mean, I’m guessing that before I was even aware of my surroundings and, you know, who my parents were, I probably had seen roads, but not known what they were. They’ve just always been there, at least for us here in industrialized cultures.

[00:12:11] So you mentioned that so many of the roads that we have, the infrastructure that we have, that exists, facilitates access and I’m also recollecting from your book, there was a surprising agency who seems to be the largest, I don’t know what the right word would be maintainer of roads, developer of roads, in the world.

[00:12:31] Ben Goldfarb: Manager, perhaps?

[00:12:33] Michael Hawk: Manager. Yeah. I’ll let you tell that story. Who is this surprising agency and why do they have so many roads?

[00:12:40] Ben Goldfarb: Yeah, so the largest road manager in the world is very likely the U. S. Forest Service, which I think comes as a surprise to most people in that, you know, we think of the Forest Service as managing forests, you know, these large blocks of relatively intact habitats. but in fact, there are something like 400, 000 miles of Forest Service roads.

[00:13:01] some forests have, higher road densities than New York City, believe it or not. and, the reason is, is basically a lot of it is the history of the, the historic timber industry. that’s a, a big part of it, cutting roads to access timber.

[00:13:15] and, you know, a lot of it is, is also the, the Forest Service’s own. compulsion to manage or steward or intervene in its, own lands, it’s kind of amazing to go back and read some of the, diaries of early forest service rangers talking about how important it was to open up this country with roads so that if a beetle infestation happens, you know, you can cut the, all those trees out and get the infestation out of there.

[00:13:42] if a, if a fire happens, certainly a lot of early Forest Service roads and still today are built for the purposes of, fighting wildfires. the other rationales included managing fisheries and wildlife. I think that the Forest Service is really emblematic of this, this broader mindset that, we humans are these enlightened stewards of nature, and nature requires us in some ways to intervene on its behalf and roads are the way in which we get back there and, do the intervening.

[00:14:11] So, yeah, it’s, it is pretty incredible to look at, when you look at a zoomed out map of, America’s national forests, they, you know, there are this, these big green blocks of what looked like intact land, and then you actually get out into many of them on the ground and they’re just absolutely spider webbed with, dirt roads and densities that kind of beggar belief.

[00:14:32] Michael Hawk: There’s so many interesting branching points and, I, I was trying to come up with a road, pun, but I’ll spare listeners any punniness. But, you know, when I’m thinking about roads, there’s a lot of unintended impacts of roads, and I think you spend a lot of time investigating that as part of this book. one thing that comes to mind for me, just to kind of get the conversation started when I’m thinking about, okay, all these roads and Forest Service land and maybe from a satellite view, you can see the canopies are touching, but it still creates this, in a way, kind of like an edge habitat.

[00:15:04] And I often hear people talking about brownheaded cowbirds, for example, who really thrive in this edge habitat in their lifestyle, and it gives them an opening to maybe expand their range. Did you find any other interesting, unexpected impacts of roads such as habitat expansion or actually species that are benefiting from this opening up.

[00:15:29] Ben Goldfarb: Roads are novel ecosystems in, a lot of, a lot of ways, you know, in every, novel ecosystem has winners as well as losers. obviously scavengers kind of come to mind as, as, you know, primary road beneficiaries, right? Our cars are out there killing deer and elk and pronghorn and, other, other critters and, that’s being taken advantage of by turkey vultures and golden eagles and bald eagles and coyotes and ravens, there is this community of organisms that, you know, certainly benefits from the road. But, the road is also, it’s a dangerous resource, right? It can be an ecological trap, you’re a, a golden eagle, who alights on an elk carcass by the side of the highway and, fills your belly with meat. it’s pretty hard to take off when the, tractor trailer comes barreling down the, down the highway. And, you know, certainly lots of scavengers, fall victim. So the, you know, the road is kind of this, it is this, resource, this form of bounty for at least some, organisms.

[00:16:23] but you know, it’s certainly a dangerous resource and can become an ecological trap very easily.

[00:16:28] Michael Hawk: Yeah. And in fact, there was an interesting passage in the book where you talked about Sandra Jacobson’s categories for animals that, you know, how they behave when they’re on the road and they’re encountering traffic. and I think I have the list here. There was non-responders, pausers, avoiders, and speeders.

[00:16:46] so can you tell me a little bit about that and how, maybe how that relates to, these animals interacting with this novel ecosystem and a novel entity, like a car for the first time.

[00:16:56] Ben Goldfarb: Yeah, that’s such a great paper. I’m glad you brought that up, Michael, because it really did sort of, when I read Sandra’s paper, it did kind of change the way I thought about, animals and how they direct with roads. So, there’s sort of this spectrum of, responses, On one end, as you say, you’ve got, you know, you’ve got the non-responders, and those are animals that basically cross roads, no matter what the traffic is, you know, you can sort of picture frogs and salamanders, crossing busy suburban street, migrating between, from forest to a breeding pond and in spring.

[00:17:25] Michael Hawk: Kind of like they’re oblivious to what’s going on there, yea.

[00:17:28] Ben Goldfarb: They’re totally oblivious, right? They’re just hopping across the street, bound and determined to get to that pond, and you know, it doesn’t really matter what the traffic rate is, they’re just going to go for it, and they get, crushed en masse, the process. Now you’ve got the pausers, and those are animals like, skunks, or, or porcupines, you know, animals that sort of creep onto the road and then they’re sort of startled by traffic and they stop. You I think that a lot of those animals, to me, that attests to, the ways in which cars and traffic hijack evolutionary history in some ways, right?

[00:18:00] If you’re a skunk, for example, spraying your, disgusting scent is, this incredible evolutionary defense mechanism, you know, that’s, evolved over, many, many thousands of generations. And works really well against a fox, but it’s totally useless against an SUV, right?

[00:18:17] And it’s actually very maladaptive. You know, you stop in the middle of the road, and of course you get, you flattened. cars really, again, they kind of hijack evolutionary history, I think. speeders are, deer are kind of the classic examples of speeders, and those are animals that, basically looking for gaps in traffic.

[00:18:34] They’re racing through those gaps, and, the gaps between cars are wide enough, they’ll run between them, and it, but as the traffic rates increase, and those gaps between cars get smaller and smaller, they really stop trying to shoot those gaps all together, and, don’t cross. And then the kind of the, furthest end of the spectrum are those avoiders that you mentioned, you know, animals like grizzly bears that really shy away from even incredibly low volumes of traffic. and as a result, their populations often get fragmented by highways because they don’t, cross at all, you know, even, even six cars an hour, according to some studies is enough to prevent grizzly bears from crossing the, a very, very rural, rural road.

[00:19:14] so, you know, to me, I think, the takeaway there is that, it’s funny to think about the two ends of the spectrum, the, the non-responders and the animals that cross no matter what, and the avoiders, the animals that almost never cross roads and realize that, you know, in a way they’re both kind of imprisoned by roads, right?

[00:19:29] one because they, are constantly getting flattened and another because they, you know, they don’t attempt to cross at all. So, you know, no matter what your response to traffic is, as a, as a wild animal, it’s going to have negative impacts on your, life history.

[00:19:44] Michael Hawk: This construct from Sandra Jacobson’s paper is a really good way for, at least a framework anyway, to think about which animals are most impacted or maybe how to help those animals that are impacted in the different ways. So you talked about grizzly bears or some of these other non-responders on the other end of the spectrum being imprisoned.

[00:20:03] what’s the outcome of that scenario? Because you might be thinking, okay, for a grizzly bear, they’re not crossing the road, so they’re not getting hit by a car, but there are other negative side effects of staying home essentially.

[00:20:16] Ben Goldfarb: Yeah, it depends on the organism, but you know, certainly, in the case of grizzlies, you know, lots of research shows that they’re genetically fragmented and isolated by highways, or at least, certainly many populations are, they can’t cross roads to find new mates and, you know, and, and, their gene pools kind of stagnate as a result. they’re kind of the archetypal example of that, you might talk about more later, or the mountain lions in Santa Monica mountains, you near Los Angeles, which are so surrounded by freeways, like the 101, that, they’re male mountain lions in that population have ended up mating with their daughters and granddaughters and great granddaughters, you know, and now they’re starting to develop, kinked tails and undescended testicles and other sort of symptoms of, chronic inbreeding.

[00:21:00] certainly there are genetic consequences to that kind of fragmentation. And they’re also, profound, consequences for animal migrations as well. in the book, you know, I read a lot about, about mule deer migrations and, you know, the American West in places like Wyoming and Colorado where I live and Montana and elsewhere, got these herd, these migratory herds of mule deer and elk and pronghorn, need to move between habitats, especially in fall, they have to get down to those, low elevation winter ranges, and highways are preventing them from doing that.

[00:21:30] And as a result, there have been cases of mass starvation,because, you know, highways like, like I-80, are preventing them from reaching these really critical winter pastures at, at lower elevations. So, you know, not crossing highways in some ways as some research, researchers pointed out to me, you know, it’s almost more dangerous than attempting to cross, you’re a big herd of mule deer, the herd itself can survive a few road kills in all likelihood it. What it can’t survive is, mass starvation because it hasn’t been able to reach its, its winter range.

[00:22:00] that barrier effect of roads can be even more harmful than, roadkill itself.

[00:22:05] Michael Hawk: Yeah, that makes a lot of sense. And I think this is one of the biggest eye openers for me over the last several years that as I’ve started to learn, the impact of roads is the, you know, lack of gene flow and the trapping and then the resource access as well. that’s something else is the landscape is always changing.

[00:22:22] Habitats are changing. There’s always succession. climate’s changing, everything is changing. So, what maybe could have been a sustainable situation where there was water and food could change very quickly as climate changes, as the landscape changes too, and it forces animals to move.

[00:22:38] Even if it’s not a migratory movement, it may be out of necessity for resource access as well.

[00:22:44] Ben Goldfarb: Certainly. I mean, I think about the, you know, the megafires that are increasingly prevalent in the, in the, in the West, if you’re a wild animal, living in a place, that’s suffered a, you know, a megafire, and it totally burned over, of course you need, you need to find new habitat somewhere and, certainly there are cases of roads preventing animals from doing that.

[00:23:04] So I think you’re exactly right. You know, drought, fire, these other climatic, conditions are, increasing the imperative that animals be able to move between patches of habitat and roads are exactly the problem that are preventing them from doing that.

[00:23:17] Michael Hawk: So we’ve been talking about some of these maybe unexpected impacts of roads and fragmentation of habitat, but there was, you opened the book with a fascinating example that, you know, I, I don’t think a normal person could have come up with, you know, if they were given a hundred years to think about all of the potential impacts of roads and that’s how cliff swallows have responded.

[00:23:39] So can you tell me a little bit about what has been found with cliff swallows?

[00:23:42] Ben Goldfarb: Yeah, this is just, some unbelievably interesting research, done , by Charles Brown, a cliff swallow biologist in Nebraska. and, you know, basically what he found through many, many years, about three decades of, cliff swallow surveys, is that, you cliff swallow roadkill has dramatically decreased over time.

[00:24:00] You know, cliff swallows, of course, they make these little mud nests, up in the, the kind of the, the girders and trusses of highway overpasses and bridges. And, that infrastructure has furnished habitat for them. But of course it’s also very dangerous, right? You know, living, on the bottom of a highway underpass or overpass.

[00:24:18] it’s a pretty dangerous place to be and, you know, they certainly run the risk of getting hit by cars and trucks, as you swoop around, feeding and, living your lives. , what Charles found over many years was basically that, cliff swallow roadkill has decreased dramatically, and when he examined the bodies of cliff swallows, many, many years and decades of specimens, what he found is that the wings of cliff swallows are becoming shorter over time, and the reason for that is that if you’re a long winged swallow, long wings are good for long, straight, powerful flights, whereas shorter wings are good for agility, you know, tight maneuvers, little rolls and pirouettes, you know, and those are exactly the maneuvers that you need to escape, an oncoming 18-wheeler. if you’re living under a highway, or above a highway, rather, you know, you want those short wings, to help you avoid traffic, and, traffic is basically you weeding out the long-winged swallows and selecting for, the shorter-winged swallows.

[00:25:20] That’s, very rapid evolution driven by cars and trucks and traffic. And I just found that, you know, an incredibly powerful story on some levels. I mean, first it just demonstrates how powerfully and dramatically and quickly roads have the ability to shape the natural world. I mean, that’s again, roads, causing evolution, in, matter of several decades, you know, a geologic blink of an eye.

[00:25:46] I also loved that story and, opened the book with it because it’s, you know, it’s not exactly a hopeful story, but it is a story of adaptation, you know, and I, I think that, when we think about the ecological effects of roads, it’s very easy to just think about all of the, catastrophic ones, you know, roadkill, habitat loss, noise pollution, etc.

[00:26:07] And of course, you know, all of those, all of those negative effects exist, and that’s largely what the book’s about, But roads are, they’re, they’re not just forces of destruction and habitat loss, they’re also forces of habitat creation in a sense, and all kinds of creatures have really interesting evolutionary and, and adaptive responses to roads and, you know, I’m interested in those, those stories as well, rather than, very straightforward story of roads causing destruction.

[00:26:32] You I like a more complicated story in which roads are novel ecosystems in their own right that induce all kinds of interesting, ecological and biological responses. I just thought that was a fascinating story that, kind of complicated, the role of roads in some interesting ways.

[00:26:49] Michael Hawk: it’s right in line with how I think about the world as well, because roads aren’t going away and we need to understand what those impacts are so that we can do better. and seeing both sides of the coin I think is really helpful. I’m sitting here thinking to that if colonists were coming to North America, and of course this would not exist, but if they were coming and identifying all of the animals and species and giving them names, you know, giving them English names, and they found today’s cliff swallows, nesting under bridges, they would, they’d probably be called bridge swallows. Like that’s what, that’s what they’ve become. They’re more common under bridges than they are in their traditional native habitat, which is crazy to think about. And I think their range is actually expanding as well since, bridges are kind of everywhere.

[00:27:36] Ben Goldfarb: Yeah, yeah, absolutely. You know, and again, you see that with, with lots of different organisms, like the, meadow vole, you know, there’s a great, a great study from the, the seventies, I believe that basically showed, meadow voles expanding their range, sort of in tandem with the interstate highway system.

[00:27:50] following those kind of grassy verges, roadsides and medians, this new form of habitat. the EPA, put out a white paper some years ago that, described, vultures expanding their, their habitat, basically, you know, in these linear strips along, highways, you black vultures moving north, with the highway system. so yeah, look, obviously, you know, roads are, roads are destructive, but, to assume that they’re only destructive almost doesn’t give wildlife enough credit. Right. that wild animals are incredibly adaptable and intelligent and good at exploiting the resources that we provide for them.

[00:28:27] And, you know, it shouldn’t come as a surprise that, they, they’ve figured out ways to exploit our, our road system as well.

[00:28:33] Michael Hawk: Yeah, absolutely. And they need some help on their own evolutionary timescale. You know, it seems like cliff swallows are well positioned to rapidly adapt. Whereas a mountain lion or a grizzly bear with a much slower reproductive cycle and some other behavioral differences are going to need some help to adapt and sustain.

[00:28:53] I wanted to pick up though on you, you started to talk about the roadside strips and the meadow voles. And I had a past guest on the podcast, Dr. Jarret Daniels, who, he’s an entomologist and has really looked at the importance of roadside vegetative management as a way to help with insect populations.

[00:29:13] So I’m curious if you delve into those sorts of topics as well, you know, for example, I don’t know what the statistics are, but if we just think about interstate roadsides, highway roadsides, all being managed by state entities, essentially, it seems like there’s a lot of potential there for improvement.

[00:29:33] Ben Goldfarb: Yeah, absolutely. And I wish I’d talked to Jaret Daniels. He sounds like a, he would have been a good, a good source for my book. Yeah, I think that, there’s something like 17 million acres of, of roadside habitats in the, in the United States. So it’s, you know, it’s certainly a, a big form of, the habitat, of land.

[00:29:50] in some states in the Midwest, it’s the largest form of public land in the entire, state. and, you know, certainly there is a lot of, a lot of potential there. You know, you think about, I mean, one chapter of the book deals with monarch butterflies. the midwestern migration, not, your California population.

[00:30:04] there, I mean, those, those butterflies, you know, they’re, passing through the breadbasket, right? They’re moving through, these vast swaths of land that have been converted to corn and soy monocultures, there’s not a lot of, milkweed for, not a lot of, of sustenance, with the exception of roadsides, which are in some ways, the last wild places.

[00:30:25] in these intensively agricultural cultivated landscapes, but, as we talked about earlier, you know, roadsides are, they’re, they’re dangerous habitats as well, right? And, you know, certainly many millions of monarchs are, are, are killed by cars. You we don’t really think about, insects as being roadkill exactly, but, they certainly get hit.

[00:30:45] so, there’s a lot of, a lot of emphasis now on managing roadsides for pollinators. And, you know, I think broadly that’s, certainly a good thing because, these insects need all of the habitat they can get. You know, they’re definitely, milkweed limited, to a large extent.

[00:31:02] but, the same time, you know, we have to, manage those roadside habitats, in a way that acknowledges that they’re, potentially dangerous places. You and there are things we can do like moving that those habitats further from the shoulder, potentially, or higher up, on embankments so that the butterflies, you know, are moving over traffic rather than, directly, in the, in the midst of it.

[00:31:22] to me, certainly there’s, there’s potential there for roads to sustain, pollinators, but, we also have to be thoughtful about, the negative impacts as well.

[00:31:30] Michael Hawk: Right. There’s interesting ethical question in there where you could plant a bunch of milkweed or other native plants along the road and give a population a stronger likelihood of surviving. But at the same time, if it’s done willy nilly, it’s a, it’s a trap as you used before, an ecological trap, to some extent, you’re going to increase roadkill that much more as well.

[00:31:49] So on the population side, it sounds good. On the individual side, it’s, it’s really interesting to think about. And you mentioned early on to the impacts of road noise and how that can dissuade animals from even approaching in the first place. Can you elaborate a little bit on that?

[00:32:05] Ben Goldfarb: Yeah, certainly, road noise is, is this huge pollutant, it’s, it’s funny, it’s like, it’s such a, like roads themselves, you know, it’s such a part of our own lives, while I was working on this book, I lived in Spokane for the most part, in eastern Washington, and, you know, I was living, probably a quarter mile from I-90, and on this busy arterial, and I didn’t quite realize the extent to which all of that noise was impacting me until you read the literature. about the human health effects of road noise and, you know, and realize that, I mean, that kind of constant racket, that stress, is raising our blood pressures and, you know, making us more susceptible to stroke and cardiac disease all kinds of problems. I mean, I mean, road noise is literally shortening our lifespans. it’s, it’s one of the great, I think, unsung public health crises of our, time. You know, and it has, it has kind of a similar, effect on wildlife as well.

[00:32:57] You know, there are lots of, studies showing that, know, animals avoid noisy areas, or, they have to modulate their calls, if you’re an amphibian or a songbird to kind of be heard over the din. road noise is really a form of habitat loss.

[00:33:11] You know, we don’t really think about it in, in those terms, but, if you’re an animal, a wild animal, you know, your, hearing is indispensable, right? That’s how, if you’re an owl or a fox, you know, that’s how you detect your. And, if you’re a prey species, that’s how you detect your predator, right, is, primarily through hearing, and so if you can’t hear, you’re going to avoid area.

[00:33:32] And, think like the most, ingenious study to this effect that I write about in the book the phantom road experiment, which was conducted in Idaho by researchers at Boise State University. And, basically what they did was they recorded the sound of traffic, and then they played the noise of the road, in this otherwise unroaded, forest, during songbird migration season.

[00:33:56] And, you they found very clearly was that, birds tended to avoid that noisy area, and the birds that did stick around, were in worse body condition because, , they were sort of constantly having to look around for predators rather than hear them, and they, fed less as a, as a result.

[00:34:13] So they were kind of skinnier and less equipped to, complete their migration. So that was just, a brilliant study that, proved, I think very conclusively that, isolating noise as a variable, road noise is, is still a, a huge issue.

[00:34:27] Michael Hawk: I love the way those researchers think when, when I hear a good study like that, where they’ve been able to isolate a single variable, because if it’s, it’s pretty easy to think in the flip side and try to look at an existing road and see what’s going on there. But then at that point, so many other variables have been introduced.

[00:34:40] So the phantom road experiment, I just love that one. It’s a, such a great example.

[00:34:45] Ben Goldfarb: Me too. Yeah.

[00:34:47] Michael Hawk: And you think about the implications of that too, there are some other studies that do look at who is successful near roads and, you know, they found that, as you said, they may be modulate their calls or songs differently.

[00:34:58] but again, we’re selecting winners and losers in that case, essentially changing the makeup of the food web around us. So we’ve talked about the physical impact of roads and the noise impact. What about the lights, the headlights, the street lights?

[00:35:14] What kind of impact does that have on the ecosystem?

[00:35:17] Ben Goldfarb: it’s a great question. I mean, I, I actually wish I had, I had addressed it more in the book. Honestly, , there’s a lot about noise in there and less about light pollution. Certainly light pollution is a huge, a huge issue. Obviously, course, so many nocturnal species that rely on darkness and, to hunt and to avoid predators and to feed, if headlights or, streetlights deprive them of that darkness, you that like road noise is a form of habitat loss, you know, and I think that’s something that’s something that wildlife crossing designers and engineers are increasingly conscious of, the fact that, you can have this wonderful wildlife crossing, but as research shows, if that crossing is brightly lit and noisy, animals are less inclined to use it.

[00:36:00] and, you have kind of an ineffective crossing as a, as a result. , I’m sure we’ll end up talking, about the famous Liberty Canyon Crossing over US 101, outside of Los Angeles, you know, and there, I mean, the designers, really gone to great pains to mask some of those light pollution impacts, through vegetated screens and berms and walls and other, other measures.

[00:36:21] So, think that light pollution, like noise pollution is something that ecologists are , increasingly cognizant of, and, you know, are trying to, manage.

[00:36:30] Michael Hawk: Absolutely. And before we get into the Liberty Canyon Crossing, I wanted to get back to as well. I jotted down, you mentioned like salts and de-icing chemicals and things like that. I admit I’ve, I’ve spent very little time looking at that.

[00:36:41] I mean, obviously, it would impact the ability for plants to grow because you’re changing the composition of the soil, near those roads. What other impacts do chemical treatments have on roadside ecology?

[00:36:55] Ben Goldfarb: Yeah, it’s a, it’s a great question. And you know, I mean, certainly it makes sense that you haven’t thought about it because you live in California, you a it’s not, it’s not really necessary, you know, but road salt as, a de-icer, is applied in, in just mind blowing volumes, in the upper Midwest, in New England, places where, roads freeze.

[00:37:12] and, it has huge impacts on so many levels, you know, there are, many, many studies showing that it does everything from, make frogs more susceptible to disease to stunting the growth of, everything from plankton to trout. many lakes and, and streams are becoming brackish, kind of a famous case where marine crabs infiltrated a stream in Canada because it was so salty that they were able to survive.

[00:37:38] it’s one of the ways in which roads are an ecological trap as well. Right. I mean, many animals are salt limited and they, crave salt. creatures like moose and bighorn sheep, you know, end up, going to roadsides to, lap at these little salt ponds and wetlands that, form along, along roadsides and even lick parked cars in, winter. And, you know, obviously anything that draws animals closer to the road or even onto the road, is going to be really, really dangerous for them. So there are, you know, lots of studies showing that, road salts enhances this ecological trap effect. So, road salt again. It’s something that, we kind of take for granted in a lot of ways or don’t even notice. I mean, certainly it is useful at, to a very large extent. It’s, it’s, saved lives, many human lives undoubtedly by, preventing car crashes, but, you know, it certainly has ecological consequences.

[00:38:27] Michael Hawk: and I guess looking to the future, this may be way too much speculation. It’s obviously really important for a car centric culture. So an obvious improvement would be mass transit systems, better mass transit systems that are safer. do you know of any chemistry or other, you know, maybe interesting design or engineering solutions to having to apply salts to improve safety of roads?

[00:38:53] Ben Goldfarb: Yeah, , there are a couple of research groups working on, different, de-icing chemicals, you know, some that are derived from beets, some that are derived from, I think apples, other, agricultural waste products, and, , those have,, some potential certainly. , the beet thing, I think people complain about the smell of, beet smothered roads sometimes, And, you know, so, I mean, there, there are other options out there that are being developed, but, you know, salt is just, so ubiquitous, it’s so cheap, it’s going to be, uh, very hard to dethrone, I think.

[00:39:23] Michael Hawk: All right. So we’ve mentioned a couple of times the mountain lions in LA and the Liberty Canyon Crossing, and for a deep dive on that, I’m going to point people back to an episode I did with Beth Pratt probably a little over a year ago. but there was an article in the LA times last year about this crossing.

[00:39:42] It’s called the Wallis Annenberg Wildlife Crossing at Liberty Canyon. It’s a mouthful. I think the title of that article was something like The Age of Wildlife Crossings, or that was the point that they were making in the article. Do you agree that we’re entering an age of wildlife crossings?

[00:39:59] Ben Goldfarb: Yeah, I do. I do think that’s a fair and accurate statement, you know, and certainly Liberty Canyon has a lot to do with that. this incredibly high profile, certainly the highest profile wildlife crossing ever built. by virtue of being, you know, very close to, giant, megalopolis and crossing, the busiest freeway in the country. you know, it also has as its mascot P-22, who was probably the most famous wild animal in the country, thanks in large part to Beth’s, advocacy and, promotion.

[00:40:29] So, you know, I think the Liberty Canyon did a huge amount to raise the profile of, wildlife crossings and, make them, It appeared to be a viable solution, you know, I mean, the kind of interesting thing about Liberty Canyon, about the Wallis Annenberg Wildlife Crossing is that, it was, it’s built or it is being built primarily with , private donations, rather than that, like there is some public money in there from Caltrans, but you know, it’s, it’s mostly private funding, and you know, that’s, good.

[00:40:55] but that, philanthropy exists, but, you know, I think that, that ultimately, the goal here is just to get wildlife crossings embedded in the public transportation budgets, because certainly the public has an interest in, making the highways safer, both for wildlife and for drivers.