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Nancy Castaldo, "Squirrel: How a Backyard Forager Shapes Our World" (Island Press, 2025)
00:40:59
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- [00:01]
A
Welcome to the New Books Network.
- [00:06]
B
Hello, and welcome to another episode on the New Books Network. I'm one of your hosts, Dr. Miranda Melcher, and I'm very pleased today to be speaking with Nancy Castaldo about her book titled How a Backyard Forager Shapes Our World, published by island Press in 2025. And this book, as the title suggests, takes as its subject matter the squirrel, which are everywhere. Like, actually everywhere. Nancy is in the US at the moment, I'm in the UK at the moment, and yet I think we both probably could pretty easily go outside and find a squirrel. Whether we're in the wild, whether we're in the middle of a city, they're all over the place. And yet, despite that, we don't know a lot about them in some senses. And certainly many of us, I think, every day, don't know a lot about them, which is why this book is so fascinating, because it really gives us an insight into a world that's, like, right there, outside, all the time, but we don't often think about. So, Nancy, thank you so much for joining me on the podcast to tell us about squirrels.
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A
Oh, thank you so much. I'm so happy to be with you today.
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B
Well, I'm very pleased to have you as well. Could you start us off by introducing yourself a little bit and tell us why you decided to write this book? How Important Are Squirrels?
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A
I'd love to. Well, I am an environmental educator with a science background, and I've written books about the planet for decades, most of them for young readers. This is my first book for adult readers. Squirrel How a Backyard Forager Shapes Our World is a little bit of a departure for me. I've written many, numerous articles on science topics and food and farming and water security and things like that. But I felt it was time to take a look at squirrels. Like you said, they are everywhere. A lot of folks asked me, why squirrels? That seems to be the first question I'm always asked. And I always respond with the same answer. Why not squirrels? They are everywhere, but we do not know everything about them that I feel since they seem to be everywhere, we should know. They entertain us, they frustrate us. And I really wanted to dive really deeper into what their importance is, what roles they play, and how do these little creatures that are often the first mammal that we see as children in the wild and develop a relationship with how they are important and what their roles are at this point in our wild world?
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B
I mean, that's a pretty good answer to why squirrels, right? Why not? There's plenty to get into before we get into some of the. More details, then, is there anything further we want to sort of lay out as our foundational understanding for why they're important? Yes, it's definitely that we encounter them a lot. We encounter them as children. Any other reasons why they're important we want to clarify now?
- [03:06]
A
Well, there's a lot of them out there. Like you mentioned, they are all over the world. There's close to 300 species, including tree squirrels, ground squirrels, and flying squirrels. But they do play so many different roles in our world. In squirrel, I discuss some of those roles as ecological engineers, as cultural symbols, as dinner pests, and even roles that help us as humans, like sniffer squirrels. If you've ever heard of dogs as detection dogs, that squirrels are sometimes filling that role now. So that's just some of the roles. So there's so many aspects that we can discuss, and I discuss so many of them in the book, and happy to dive into some of those with you today.
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B
Yes, we'll see how many of them we cover. But I think the first thing we have to pick up from that answer is how many kinds of squirrels are there?
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A
Yeah, close to 300 species, about 285. And that's really around, completely around the world. It's very often that. That people see one species, so they think there's only one species around them. In my backyard, for example, I will see North American gray squirrels. I will see American red squirrels. But I also know that there are flying squirrels out there that are nocturnal that I'm not seeing. But very often we kind of pinpoint, but we don't see. There's so many more out there. And we don't often realize that the squirrel family is very large. So when I'm talking about those squirrels that I just mentioned, I left out a couple specific ones that are out there that I often don't think of as squirrels. Chipmunks, little ground squirrels. We just celebrated in America Groundhog Day. Groundhogs are a part of the squirrel family. So there's so many more species that are in our world that are unnoticed.
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B
Yeah, that was something I learned pretty quickly reading the book. Like, okay, I was so off in my estimate. If you had asked me ahead of time of how many kinds of squirrels there are. So that's already something we've learned. You know, just a few minutes into our conversation, thinking then about these species being, as you said, everywhere in the world. And of course, they are ubiquitous in many cases, but we should be, of course, careful not to assume that just because we see lots of, some kinds of squirrels that they're kind of all living happy lives. Right. So do we need to be thinking about these squirrels or at least some of them being endangered or at risk?
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A
Exactly. You know, I like to compare it to how we think about weather and that we can look outside our window and we can see rain coming down, but you know, five miles away it might be sunny and clear. And it's the same thing with squirrel species. We might see a lot of squirrels out our window, but that doesn't mean that those squirrel species are doing great everywhere else. So it's very different. And sometimes there's pockets that are being threatened. We have a lot of things at this point in our world that are threatening species all over the globe. Climate change, habitat loss, wildfires, and war can actually wipe out an entire population very quickly. So there's, there are endangered species, endangered squirrel species that most people don't, don't even think they think they're, they're so prevalent. We in the United States have two squirrel species that are, are endangered right now. One of them really stuck with me. It's the story of the Mount Graham squirrel, that the Mount Graham species lives at the top of a mountain. Mountain is Mount Graham in the state of Arizona. And if you can picture this, it's a mountain with desert all around it. At the top of the mountain there are trees and the habitat is very Mount Graham squirrel friendly. The squirrels cannot come down the mountain and cross the desert. They wouldn't survive that. So that small population of squirrels that only exists on that mountain is very fragile. And they have seen that fire wildfires, which are more prevalent now with climate change, can really wipe out an entire population. So there's species like that also there's a species of ground squirrel in the Ukraine that is threatened by warfare. A single bomb could wipe out an entire colony of these little ground squirrels. And when things like that are going on, when we have a war, it's often not during the war that we can study these species. It's often after. And then we find the sad statistics. So there's so many things that make them fragile in so many places, and yet there are other species, other squirrel species that are flourishing.
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B
Yeah, no, a much more complex and nuanced world that you're taking us into already and definitely helpful to keep in mind. And of course, those are things that kind of the general public or the non squirrel expert among us, myself included, did not know before reading your book and listening to you tell us about it, but you also discuss in the book that there are some things that even squirrel experts don't know about yet. What are some of those mysteries and why do they persist?
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A
Well, you know, a lot of the mysteries basically have to do with where our squirrels are located and their behaviors. So if you take a look at the IUCN Red list of threatened global species, which is very well known, and you can look at it online, it lists all the species in the world. And you notice that when you go down through the list of squirrel species, there's so many that don't have any data at all. And that's because some of these areas are so rural that they haven't had scientists go in and actually study the populations. And also many of these squirrels are nocturnal, which also leads to less studies. And then there's the other big factor out there that there's not a lot of money for squirrel research, that these scientists and researchers are competing for money to do their research with a more iconic species that, that might attract a lot more attention. Squirrels don't attract a lot of attention. So there's a lot of things about their caching and about their roles that, that still have to be studied. And in some cases we don't know what we don't know. That's part of the problem. Without some of these studies, yeah, that's.
- [10:11]
B
Definitely a big unknown area to kind of keep an eye on. But of course that's only one aspect way squirrels are important in our societies that you touch on in the book. So getting to some of the other things you mentioned earlier as threads for us to pull on, what are some of your favorite ways that squirrels have appeared in stories across different times and places?
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A
I have to say I am a big fan of reading folk tales and mythology and oral histories. And it's so interesting to look at all of those different ways that squirrels have have found their way into our storytelling. They've found our way into graphic novels of songs, media. There have been squirrels along the the years that have taken front and center celebrity status in the world, showing up in magazines and clothing. There was a squirrel in, in the United States that was quite the personality and, and appeared in many, many magazines for a while. So those stories are always fascinating to me and it's always fascinating to see how those stories reflect the behaviors and what we do know about squirrels. So for example, there's a Native American legend about an oral history story that talks about how squirrels helped humans discover how to make maple syrup. And it's by Watching this squirrel behavior of eating the SAP. And it's a wonderful story. There's a wonderful Hindu story about squirrels helping. It's one of those stories that talks about size, and it doesn't matter how small you are, but you can make a difference. And it's a story about all the other animals looking at squirrel, basically, and saying, like, you can't help. You can't do anything. And squirrel moves these little tiny stones one at a time, and of course, creates. Creates a big difference, a big impact. So there's. There's so many different tales. And if you delve into some of these stories, wherever you're located in the world, you'll find that they have been a fixture. And the reason they're a fixture is because they've always been around us. And people from famous artists and visual artists and storytellers have always observed and used those observations in their paintings and music and storytelling. So it's extremely fun. I have Norwegian heritage in me, and I learned about Norse mythology and ratoskir, which is the. The little squirrel in Norse mythology that. That runs up and down basically the tree of life, and found out that there's. That little squirrel is on a coin, and was able to find that little coin in my great grandmother's coin purse. And all of these little stories, you know, become personal. And you can see how beloved and also how frustrating our squirrels can be in the observations that find their way into all of these stories and art.
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B
Those are some such fun ones to pick out. And obviously, I think on this topic, we could keep talking for hours, but we don't want to just stay on this one aspect of squirrels. I think I'd like to move next to kind of a key environment where many of us encounter squirrels. And obviously where a lot of those stories sort of come from, or at least more recently those sorts of stories come from, is those encounters in, for instance, parks. And to me, at least, it's kind of hard to imagine parks without squirrels. But has that relationship always been there?
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A
It hasn't. And it's fascinating because urban parks tend to be a place where we can go and see squirrels wherever we visit. I had the situation of visiting the state of Idaho a couple of years ago when I was working on this and went to Boise and found a squirrel in the park. The first day that I was there, and I looked at it and I looked at it and looked at it, and I thought, okay, that squirrel has a familiarity, but it doesn't quite look like my squirrel at home. And it's that little sense of that familiarity. That's interesting, too. And that has why so many people are drawn as visitors to another country to see squirrels in those environments that are a little different from the squirrel that they might find at home or similar. But. But it lends to that story. And they weren't always there, of course. They have been across the lands way before cities even existed. But as cities grew across the world, native wildlife is pushed out by the buildings and the people, and then they're not there. So in America, there was a situation where in the 1800s, the Industrial Revolution was creating a great flow of people to cities, which happened across the world. More people moved from rural areas to cities. And as in the case of all of those other places, they did not see their native wildlife anymore that they were used to seeing. And folks in this city of Philadelphia decided that those people needed to see that it would be good for their souls to encounter some of that native wildlife that they may be missing. So they decided to actually pack up some squirrels from the countryside and bring them in with nest boxes to the city of. To Philadelphia, to this park called Franklin park, which is interesting because it's named after Ben Franklin, who was a very strong proponent of squirrels and had many squirrel pets. So it was very apropos that he. That this park was named after him and became the site of this first reintroduction of squirrels to city parks. It was so successful, these squirrels became quite the hit that other cities decided to do this as well, including New York Central park, including the park that I visited in Boise, Idaho, including Boston Commons, and including cities across the world, including in the UK and in Italy, specifically in London and also in Torino in northern Italy. So it's fascinating to see how this reintroduction can create a viewing. A viewing site for people, an attraction that people are drawn to, but also a little bit of. Of chaos as well, as these squirrels mix in with native species and other aspects of city life.
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B
Yeah, we'll definitely get into the interactions of squirrels with others in a moment in both good and bad ways. But to get a sense of just how successful this reintroduction was, for instance, in New York Central park, like, how many squirrels are we talking might be in somewhere like that?
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A
Well, there's hundreds now. And those squirrels in Central park had it made in the beginning because they were very well fed by wealthy New Yorkers. And some of them even had very extensive apartment houses, tree houses that were constructed for them, which was. There's pictures in newspapers of these very extravagant. They even had some of them, had little porches for the squirrels to sit on. They were really very detailed. But. But we don't know exactly the number. Today there has been a squirrel census in Central park, which was great, and it was a wonderful way to bring attention to this species that's much loved and much maligned and viewed in Central Park. But, but these, these census, these population studies aren't always, in fact, very infrequently carried out. So we don't always know the population, which is something that I think would be great to do is have that as a regular event to go out and try to figure out how many squirrels, how many species are in a location. We don't have many of those.
- [19:17]
B
Who knows, maybe we'll have more in future. Thinking, though, about those interactions. For instance, when the squirrels were reintroduced and you said it was quite a hit, right? So thinking about some of those conceptualizations, right, like as pets, is that the hint? Is that the way in which they were a hit, or is it more sort of like, oh, this is kind of fun, but actually they're sort of a nuisance or maybe they're a bit of a pest. Like, how have they been viewed?
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A
Well, they've always been viewed as pets and pests, pests in farm fields, agriculture in our attics and our backyard bird feeders, but also very beloved pets and entertaining wild mammals. So we, they do have, they do have these, these, both. These roles. You can find them all over social media right now where there's, you know, I hate squirrels social media group or I love squirrels social media group. There's so many that I found while I was doing the research. It, it was really amusing to see them all. But that's part of the squirrel story, is that everybody has one. Everybody has a story that focuses on them as a joy and entertainment or a nuisance factor. I'll admit I love watching the squirrels in my backyard, but I also have a story about a squirrel coming down our chimney, into our house, all covered with soot and running through the house. So we could both have both of those feelings at the same time for species and just basically appreciate their role and what they do. But there has been situations where they have caused some chaos with power outages and also with other species, including in the UK and northern Italy when they. When our North American gray squirrels were brought as pets to both the UK and Torino, Italy, and, and became loose. So very often pets do not remain in households until their deaths. They find their way out. And squirrels are notorious for finding their way to other locations. And when they're released into the wild, they can really disrupt the balance of the other wildlife that's there in the native species. So even on my trip to Torino a couple Years ago, about 10 minutes after I had gotten off of the train and was visiting the major park in Torino, I found a North American gray squirrel that looked just like my squirrel outside my door. And it was very far from home and a little unsettling to see it in a European city. And also, of course, when that happens, as in the uk, it pushes out the European little red squirrel. So it can create quite a disruption when released as pets into the wild.
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B
Yeah, that definitely takes the whole pets versus pest thing and shows that that line might be blurrier than we would think. And of course, these sort of individual incidences of interlopers definitely exists, as you have given us some examples there. Anything more systematically we should understand about squirrels as invasive interlopers?
- [22:51]
A
Well, I think we really need to make sure that as first of all, wild animals, I'm a fan of not keeping them as pets. We should really be careful about that. And we're finding that as. As invasive as they are in these locations, it has led to a tremendous amount more research just trying to manage these species. So while they're cute and friendly, their. Their problems have actually led to more squirrel research when they don't belong in an area, which is a somewhat positive side of having them in those areas, Although it doesn't make up for the fact that Eurasian reds are having such an issue. So it's a mixed bag out there. We definitely need the research. We need to know how to manage our wildlife better. And how to coexist is really the main thing with wild animals. And I think if anybody, it's anything out of my book on squirrels, it's how. How do we coexist with. With our native wildlife, with wildlife in general, when we are attracting animals to our bird feeders in the backyard. You know, squirrels aren't great at reading the room. They don't know that that bird feeder is only for birds, you know, but that's what we're doing. I think, as the problem is, we draw them in. We want the trees to shade our houses, but we don't want the squirrels to use those same branches to come into our attics. So I think part of the issue is how we manage our coexistence with all these wild species.
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B
Yeah, that's definitely very much an issue of the present and one for the future as well. But if you don't mind. I'd love to take a detour back into history for a moment to discuss one aspect of the book that I found very intriguing. Because, of course, as a historian more broadly, it's not a huge surprise for me to read a book and see that when we're talking about US history, for instance, 1968 is a year that comes up for a number of reasons. Right. There's a lot of different histories that can be told about that year. I was kind of surprised that there was. It was a significant year for squirrels, too. So what was going on there?
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A
Oh, my goodness.
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B
Right.
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A
I mean, 1968 was just a year packed with such notable events in the news. And it was so interesting for me to be going back through squirrel research and finding squirrels popping up in that same year. If I might, I'll read the very beginning of that chapter, which talks about a little bit what was happening at the time. The year 1968 was a year that shattered America. It was the year when the lid of the simmering, bubbling pot of the civil rights movement, youth culture, the Cold War and the Vietnam War exploded. The year began with a March of some 5,000 women in Washington, D.C. to protest the Vietnam War. The same month, the first televised NCAA basketball game appeared in primetime. North Korea seized a U.S. ship, and the North Vietnamese Communists launched the Tet Offensive. That spring, New York Senator Robert F. Kennedy entered the race for the Democratic presidential nomination, and Martin Luther King, Jr. Was fatally shot in Memphis, Tennessee. Soon after, students took over five buildings in Columbia University's campus, calling for the university to cut its ties to military research, leading to the arrests of 700 people and over 100 people were injured. The same week, Hair opened on Broadway, peace talks began. Andy Warhol was shot and wounded. President Lyndon B. Johnson signed the Treaty of the Non Proliferation of Nuclear Weapons. The Soviet Union invaded Czechoslovakia. The song hey Jude was released in the United States and became the longest running song to hit number one on the Billboard Hot 100. Then Autumn arrived, and with it came the Great Squirrel Migration. Amid the news of the Apollo 7 mission and the Olympic Games in Mexico City, people in the eastern United States experienced an event in nature unlike anything they'd witnessed. Gray squirrels were moving by the thousands out of woodlands and parks, crossing mountains, rivers and roads. And it was something that when I was coming across this news, you know, you think about all of those other headlines that made the national news, made the TV stations, everything was so highly noted and exceptional that year. And then along on these front pages of newspapers were These stories about this squirrel migration and you could sit there and say, like, how in the world did a squirrel. First of all, what is a squirrel migration? And second of all, how could this impact make such an impact? In our history and squirrel migrations have occurred at various times. Usually there's a mast year. A mast year is when trees produce a lot of nuts, so there's a lot of nuts for squirrels to eat. And obviously that leads to a lot more squirrel births. Population gets bigger and sometimes squirrels have to adjust their habitat and where they're going to be. That particular year there had been a big mass year and the squirrels exploded in population and therefore started to emigrate and leave in droves, as you see, because there was a lack of food and loss of habitat. They were competing with too many other squirrels. And it's significant because we could see something like a. Something that causes. It doesn't have to be a mass deer that causes a change in habitat or food security. It could be climate change, it could be wildfire. It can be any of those other things, things that I mentioned that can cause that disruption, but that can also end up being a problem for a number of different wildlife, not just squirrels. So it's very interesting, look at history to see a pattern and see what happens and be able to know what happens. If for some reason there's a blight that kills all of the nut trees, what will then happen? And what is that squirrel's role in the food web and how does that impact all the other species in that web? And of course we are part of that. Humans, of course, are an animal too. So these things are a way into exploring the roles of squirrel's play in the food web as a, a pollinator, a seed spreader, a prey and a predator, but also how we fit into that web as well.
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B
Yeah, that's definitely an interesting moment in history, but one that has lessons as well for the present. Now, of course, I've been directing this conversation as we've been going to some extent, just based on what I found really surprising from the book and thinking that other listeners might be intrigued by those pieces as well. But was there anything you were surprised by in putting all this together that you want to share with us?
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A
Well, you know, I took an interesting perspective because I am not a squirrel scientist or a squirrel ologist, as many are called. I came at this from a lens of a writer, of science writer, psychom person. That was a lot of this was new to me. So my curiosity was exploding while I was doing this. Research. And one of the things that I found particularly interesting and that kind of stayed with me afterwards and I like to share with people when I, you know, meet them at a party. It's one of the things I say, like, did you know? Did you know? We often have this misconception that squirrels bury their nuts. Everything's random. They don't know where they are, they have no idea where they bury them. They're scatterbrained. I mean, this is the perception that we have of squirrels. If somebody is considered having a squirrely personality, that tends to be a negative. And what I found when I was researching squirrel was that their caching behavior is now being researched further. And that research is showing that it's, it's, it's much more methodical, it's much more thoughtful. It's much more interesting that squirrels, some species, not all species, but some of these species do sort their nuts by, by nut variety and type and also size. They do not forget where they, where they stash them, where their cash is, where their midden is. They can stash them. And sometimes those squirrels don't return to those nuts. Sometimes squirrels are one of the most killed animals on highways. So very often those squirrels don't survive the winter for one reason or another. And they don't return to those places where they have stored their, their nuts or seeds. And that also leads to forests growing as they do they. That's why squirrels are a keystone species in so many places. They also have this little sneaky behavior that there's squirrel species that can fake out a threat by stashing a nut underneath their armpit as they're digging so that the threat, which could be us or another squirrel, thinks that they're digging and they're burying that nut in that one place. But in, but truly they've had the nut hidden under their arm and can then go to another spot and bury it without having that threat take it away from them. So that behavior really points to the fact that they do have a little bit more cognitive ability than we often thought they did. And those, those kind of, you know, taking away those, those misunderstandings, debunking those myths that we have, those long standing things is, is a fun find.
- [34:18]
B
Yeah. No, we love myth busting. So thank you for sharing that with us. Is there anything further we want to conclude our discussion with looking at the future of squirrel populations and any glimpses.
- [34:31]
A
You know, as I said, there's so many different roles that squirrels play and our world is changing all the time. We're even finding that squirrels, certain species are changing their physicality, their actually their structure evolving based on the warming temperatures now, which is the same for some bird species. So it's a fascinating look as to, you know, how animals are being impacted. And of course, again, that leads to what, what is going to be happening to humans in the future? How will all of this impact our own physicality, our own behaviors? We also, I'm hoping that my book Squirrel piques people's interest and that that might lead to more studies of squirrels that will also lead to more support for our wildlife coexistence with all wildlife, not just squirrels. You know, it may, it may lead to finding out more about squirrel species that we haven't lost yet or ways that we can help endangered squirrel species in our own areas. So I'm anxious to see what will happen in the future and how all of the research and the roles of squirrels might change how we think in the future.
- [36:07]
B
Yeah, well, we'll definitely have to see what happens. I mean, that would be a great outcome for more research to be done into this. Are you staying on the topic of squirrels going forward? Do you have any current or upcoming projects or ideas you want to give us a sneak peek of?
- [36:21]
A
Well, you know, as I mentioned, I have been writing books for younger readers for decades and writing for adults in many different avenues, different kinds of publications. So I always have research going, Miranda. There's always stacks of books and going out. So right now I'm actually diving into another species in research, which I won't mention yet because it's so early on, but it's another, perhaps, I could say misunderstood species that resembles squirrels in a lot of ways. I find that it's interesting to delve into species that don't often get a good rap, put it that way. A lot of my writing in the past has also been done on wolves, which I'm not doing right now, but in that respect, too, finding out that, you know, so many of these species are so important to our ecosystems and, and misunderstood. So I do, I do love to kind of stay in that realm with my research and what I'm doing. So we'll have news soon, hopefully.
- [37:40]
B
Well, and if any listeners want to go directly into that realm of the misunderstood, unfairly, perhaps animal, or at least overlooked animal, they can read the book we've been talking about titled Squirrel How a Backyard Forager Shapes Our World, published by island Press in 2025. Nancy, thank you so much for joining me on the podcast.
- [38:00]
A
Oh, thank you so much, Miranda.
- [38:01]
B
I enjoyed this conversation.