In a paper published in Behavioral Ecology and Sociobiology in 1988, Joel Brown developed a method to use a forager’s giving up density on a resource patch to understand energetic, predation and missed opportunity costs of foraging and then demonstrated its utility, through field experiments, on an Arizonian desert rodent community. Twenty-nine years after the paper was published, I spoke to Joel Brown about his motivation to do this study, memories of fieldwork, and his reflections on the study’s findings and interpretations.
Citation: Brown, J. S. (1988). Patch use as an indicator of habitat preference, predation risk, and competition. Behavioral Ecology and Sociobiology, 22, 37-47.
Date of interview: 16 March 2017 (via Skype)
Interview transcript edited by Joyshree Chanam
Hari Sridhar: What was your motivation to do the work presented in this paper?
Joel Brown: When I began my graduate program, like many grad students, I didn’t really know the full breadth of ecology and evolution. I was joining Mike Rosenzweig’s lab. I didn’t even know really the full scope of his lab, his intellect, his ideas, but I did know he worked with desert rodents. I’ve always liked rodents. To me rodents represent a miniature game park of diverse species. So, on the one hand, I knew I wanted to work with desert rodent community ecology, which was very much a part of what went on in Mike Rosenzweig’s lab. But in parallel to that, I was always interested as an undergraduate with economic theory, particularly micro-economic theory. I thought it was very cool, in a very shallow sort of way. You could make a few assumptions about people, that they were rational or profit oriented or greedy and so on – of course, you can quibble whether these are good assumptions to make about humans or not – but regardless, if you’re willing to make those assumptions, you can take individual behavior and you could scale it up to how the entire system works. Of course, I didn’t know the word scalability at the time, so a lot of this is hindsight. But what appealed to me then in economic theory was the scalability. You could use the rational behavior of the individual to predict the economic system. So, when I marched off to Arizona, I had sort of the vaguest goals of wanting to achieve an intersection of this economic mindset with trying to study ecological communities. And, as will come up in some of your future questions, Mike Rosenzweig’s lab was perfect. There were a number of students that worked with desert rodents and there were a number of students that worked with optimal foraging theory. I was suddenly introduced to optimal foraging theory and I thought this was very cool. Mike himself was working with habitat selection. At that time, the reigning model was Charnov’s Marginal Value Theorem; his original patch use model. It seemed, from the students in the lab and other work, that the key elements of desert rodent communities are things like predation risk, seasonality, habitat variability, none of which were explicitly considered directly in the Marginal Value Theorem, which is, simply stated, a forager should leave a food patch when its marginal rate in the food patch equals its average rate. That was the context within which my mind started turning over as to how could we generalize this model. How could this model be generalized to consider things like predation risk, depleting resources, a heterogeneous environment of food and safety? That was, kind of, the nucleus then for the modeling, but I wanted to do fieldwork. I wanted to study the community ecology of desert rodents. So, the flip side was, how do I get the animals then to reveal to me? There was already an existing tradition in desert ecology to either present seeds to rodents in patches or to scatter seeds. And it was well recognized that if you handed rodents just seeds in patches without any kind of substrate, they would be attracted, they would tend to harvest it, but, of course, that doesn’t provide you any information on their quitting harvest rates. These models were all about the quitting harvest rate. So, I kind of knew in my mind then that if you wanted to get quitting harvest rate, you would need to have some sort of diminishing returns. You weren’t going to be able to observe this. And so that is where then, in my mind, it was very easy to take existing ideas that people had of the patch being diminishing returns. But there wasn’t much – there were some existing papers that were kind of cool about how can one create a situation where you can have diminishing returns. Obviously, if you’re working in a desert, there’s sand and there’s dirt and they’re digging for seeds, it really wasn’t me -the rodents dictated how one would make such a food patch. That was what motivated this journey of developing a viable field technique, but then requiring parallel theory development to be able to interpret the results of the data. It all sounds so much better in hindsight. Like with any graduate student, there were fits and starts. I remember once after I began my fieldwork, I was running around the desert, measuring giving up densities, I actually hadn’t finished all the theory work, and as I was running along, I had this horrifying moment when I realized that the rodents in my food patches were probably influencing the overall seed harvest of the community, at least the duration of when I was putting out my food patches, because they liked my food patches. I thought, oh my gosh, maybe all I’m measuring is my manipulation of their state. Maybe the only thing I’m measuring is how much I made their world better. That was one of those “oh crap” moments, you know, those moments when you’re doing science, Oh shoot, I’ve just put in so much work and it may be useless. So, actually, at that point, I stopped. That gets you into kind of my mindset. If the theory doesn’t jive with the methodology, I get very uncomfortable. And so, at that moment, I was having a crisis of faith. I actually sat underneath a creosote bush. That was the only shade out there. It was a hot day in Tucson. I sat under a creosote bush, turned my data sheet over, and began to really seriously examine, mathematically, an expansion. And it is those notes made under that creosote bush that eventually formed the proof that’s in the 1988 paper.
HS: So you developed the theory after you started the fieldwork?
JB: Well, I think theory development and field work development kind of occurred in a lockstep. The vague outlines of the theory, I guess you might call it the intuitive sense of what should happen, preceded the actual initiation to the field work. But I began the field work before I had fully fleshed out the proofs of the theories. But I guess you can say they kept leapfrogging each other.
HS: Were you interested in mathematics from an early age?
JB: That’s right. If I’m with a group of mathematicians, I look like a biologist, but if I’m with a group of biologists I can look like a mathematician. Mathematics has always come relatively easy for me and I’ve always enjoyed mathematics. I was never a math major. But as an undergraduate and as a graduate student, I took math courses beyond what were required. Ironically, as an undergraduate, as a zoology major, I got all my best grades in chemistry, physics and math and all my worst grades in biology classes! I guess one way of saying it is that I really like when one can connect the dots logically. For me, mathematics becomes the language of logic with which to separate out intuitive models. And I love it. We begin with an intuitive model. The lovely thing about intuitive models is they allow us to distill a huge amount of complexity, they allow us to come up with a fairly clear sort of statements of things. I would say someone like Jim Brown is one of the most outstanding intuitive modelers out there. However, you also know that intuitive models can become slippery fish. When you try to probe the logic of an intuitive model, the modeler can say, well, I didn’t really mean that. So, for me, mathematics ultimately becomes the language of logic that allows us to, without our own subjectivity, our own biases, determine what is a defensible hypothesis and a set of predictions.
HS: Were you interested in ecology and evolution too from an early age?
JB: Yes and no. I always loved nature. I spent a lot of time playing in nature as a kid. My childhood experiences over a four year period in Zimbabwe created an absolute love of game parks and African wildlife. My father was a surgeon, my mother was a nurse, and both of them were bush pilots. That gave us a chance to fly around the country. They shared my interest in nature, but that was always just a hobby. I had no role models. There was nobody who suggested that this could actually be a career. There were, of course, TV personalities, but I had no idea what it meant to be an ecologist. So, actually, when I began college, in a small liberal arts college called Pomona College in California, I began as a chemistry major. And my reason for that was twofold. One was a good reason. Chemistry is an honorable profession and offers good career opportunities. I’m sure you have many friends whose parents loved the idea of their kid becoming a chemical engineer. Trying to explain to parents that you want to study why birds flock is a harder sell! I also had a less good reason for wanting to be a chemistry major, and that was, as a kid, one of my hobbies was pyrotechnics. I realize that current events give it a bad name, but my friends and I made various incendiary devices. We were not making any political statement. We were just boys being boys. I suspect that if we’d had video games and things like that we might not have engaged in those activities. This was pre-videogame world. So, I thought that by going into chemistry I can learn many cool things. In the summer of my sophomore year, when I was not yet a biology major, I needed a job like many individuals. In the hallway, I saw an ad for undergraduate research assistants in fire ecology put out by an ecologist Bill Wirtz. I was interested in the ecology part but I didn’t really know what that meant. But, as you can imagine, the word fire caught my eye. It literally fired me up. This guy did fires! I was his man! So, I marched into his office and he hired me. He must have realized I didn’t know anything about ecology. His research was studying the effects of the fires in the mountains around Los Angeles on the vertebrates. Obviously, we didn’t set any fires, we watched a few fires, but mostly what we were doing was going into areas and essentially looking at communities of vertebrates in an area that had burned a year ago, five years ago, 10 years ago, 30 years ago. It was a space-for-time substitution, which I hadn’t heard of at that time. But there was something even more magical. I couldn’t believe it. I was getting paid to drive the zoology department’s 4×4 truck on creaky bad roads in the mountains. I was getting paid to climb trees and band red-tailed hawks. I was getting paid to live-trap small mammals. I was getting paid to radio-collar raccoons and coyotes. I was getting paid to learn how to mist-net birds and band them. I was getting paid to learn how to noose lizards. I couldn’t believe it. I was getting paid to do all the things I would do for fun. And I was being trained in all of these field techniques and getting paid while getting trained. That was my moment of epiphany. I loved it. I continued to work with Bill Wirtz for the remainder of my undergraduate career. I went to my folks and said, I know what I want to be; I want to be an ecologist. They said, what’s that? I said, I’m not really sure. They said, can you get paid? I said, yeah. They were very supportive. The other feature that I knew was I love teaching. I love being a student. I was one of those students that never wanted to graduate. And, I liked doing research. It all kind of came together at that point. I knew I wanted to be an academic working in ecology.
HS: Once you decided to do a PhD, was joining Michael Rosenzweig’s group an obvious choice? Did you consider other places?
JB: Sure. I knew I was interested in applying economic models to foraging. So, an obvious choice was Eric Charnov. I applied to work in his lab. And then I knew I was interested in desert rodents. And two names that jumped out at that time – this is sort of the end of 1979 – two names that leapt out in desert rodent ecology were Jim Brown and Michael Rosenzweig. They were both at the University of Arizona, and so I applied to the University of Arizona as well.
HS: How come your PhD supervisor, Michael Rosenzweig, wasn’t an author on this paper?
JB: I’m really thankful to Mike Rosenzweig for this. I just came back a week ago from a festschrift that my colleague Burt Kotler and I organized for Mike. He’s now 75 years old. At the festschrift, his former students, and he himself, again and again, brought up the fact that his approach to training graduate students was to be hands-off; to allow them to be independent. He provided an exciting atmosphere, he provided conceptual frameworks, if need be he would collaborate with us, but he saw his role as being truly a mentor, not a collaborator. And he never saw us, as some labs do, as if it was our job to make him famous. It was not our job to get him papers, it was not our job to advance directly any aspect of his work. He had a very sort of diffuse sense of what our role was. His job was to train us, allow us to be independent graduate students, and if in the end, by us being successful, that reflects well on him, yeah, that’s great. At that time, I didn’t know labs work otherwise. In his lab, there was no expectation. In fact, the expectation was that he would not be an author on our papers. And that really freed us up. And in fact, quite the contrary, he would make it very clear when he felt we were joining in a collaboration. So, he would invite us to collaborate with him on stuff he was doing. He did not see himself then as more than just a mentor and advisor, on the work that we were doing. This approach seems to have gone a bit out of fashion. But in my own career and my own training of my graduate students, I feel very, very strongly about that particular philosophy. I had a graduate student who just recently finished and I’m very proud of him. He’s published five papers from his PhD, but I’m not an author on any of them. Nor do I expect to be. I tell my graduate students even to this day, that if they need me or want me to be a collaborator on a project, I’m happy to. My students always join me on any project I’m working on. And that was kind of Mike’s philosophy and that kind of gift came from Mike. So, in that 1988 paper, there was never any expectation he would be a co-author. Mike was really quite clear, in his behavior and in the way he trained us, that he would neither want to be nor expected to be a co-author.
HS: How did you decide to work in this site near Tucson? Did the site have a name?
JB: No, it had no name whatsoever. Many people were attracted to the study of desert rodent ecology because there tend to be a lot of species. There can often be five to 10, even 15, different species of desert rodents occupying the site. So, that makes it a very appealing place to do community ecology work. Furthermore, many scientists, including Mike Rosenzweig and Jim Brown, all selected lovely sites that represented a variety of desert habitat types, and often a mix of habitat types, desert habitats, that often then represented this high diversity of rodents. In my case, I was looking for two things in a study site. So again, it was never directed to work at somebody else’s study site. I was looking for two things, and I just picked it myself. If there’d been satellite images, I might have made a much better choice. The argument often for studying deserts is that they’re simpler. So, instead of finding an area with a high diversity of rodents, where it might be a bit of a problem for trying to apply these economic models, I wanted to find the most boring site one could have. I wanted it to be as homogenous as possible. Also, my fieldwork was going to require me to go out twice a day. I wasn’t going to be living at my field site – I had my teaching responsibilities – so I needed a site that I could dash out to in the morning, return to the university and then I could dash out to in the afternoon, whereas, most of the grad students and others picked study sites that were too far away to drive out just for the day. I think I can honestly say I had the only desert rodent site that you could go to twice a day. Anyway, just east of the Tucson airport and a bit west and a little bit north of the city dump was this just lovely creosote flat. To me, it was the most beautiful creosote flat in the world. Why? Because three species of perennials represented 99.99% of all the vegetation. And while there were a few mesquite, palo verdes, all these other wonderful plants that make the Sonoran Desert so beautiful, there was a smattering of all these other plants, literally, on my 40 hectare site. I could count these odd ones individually. Another philosophy of Mike’s, and I carry the same kind of philosophy, is even if you hadn’t fully formed your plans, just go out and be doing something. So just so I could feel like I was being a field biologist, a good year before I actually began my study, I was going out there and trapping in the site just to see what rodents were out there, to tag them and get a sense; just do the standard thing that rodent biologists do. And I was so delighted, because there were four species of rodents that seemed important. Two of them were nocturnal, two of them were diurnal. That was going to make it easier for the foraging. The nocturnal ones were the Merriam’s kangaroo rat and the Arizona pocket mouse. And that was fun because the Arizona pocket mouse usually doesn’t show up much in other people’s studies, simply because it is such a creosote bush specialist. I suspect, and I wish we’d studied it more in hindsight, that the Arizona pocket mouse gets out-competed by the other pocket mouse species in the more diverse communities. So, I had this unusual pocket mouse, the Arizona pocket mouse, and this very common player that anchored me and almost all the local desert rodent work, the Merriam’s kangaroo rat. Desert rodent research generally focuses on the nighttime species for obvious reasons. It’s hot during the day. Trapping during the day can harm the animals. So, for a whole variety of reasons, studying rodents in the daytime has never been terribly popular. But for what I wanted to do, it didn’t matter whether they were daytime and nighttime, and in fact, having a night shift and a day shift was going to be handy, because it would guarantee that I could stratify my foragers. So, I was delighted to see the community had a large population round-tailed ground squirrels and the Harris’s antelope ground squirrel. So, by total serendipity, I found what I thought was the most boring spot in the Sonoran Desert. I jokingly call it the armpit of the Sonoran desert. It was less than 20 kilometers from the university. I could get there twice a day. And then just by serendipity there were four major rodent species, two of them nocturnal, two of them diurnal, and then to make it even more handy, one of the nocturnal species, the pocket mouse, goes dormant during the winter, so that I can simply interrogate the kangaroo rat. And, serendipitously, of the daytime rodents, the round-tailed ground squirrel also goes dormant during the winter, so I can interrogate a single squirrel. This was all serendipity. But that was kind of the motivation for the site.
HS: Did you have people to help you with the work or did you do most of the fieldwork on your own?
JB: I was the principal and only labor providing the field work. However, I am greatly indebted to other graduate students. And sometimes you see less of this today than it used to happen in my day. I think it’s because grad students get busier, they have a life, they got more things to do, but back then we had nothing to do, except our science and our field work. And so, I was blessed by the fact that some of the time there were grad students in the lab – Tom Valone, Bill Mitchell, Burt Kotler – they were willing to come out and help me run – literally run – because that’s what it took to collect the data in a timely way. They helped me run my traps, run my feed patches. And then the daughter of my game theory mentor, Tom Vincent, when she was in high school, would often come out and help me run around my study site. Most of the time, I was by myself, but a fair amount of the time, I was blessed by people that, both for curiosity and kindness and to learn new things, were willing to come out and help me.
HS: I’d like to quickly run through the names of the people you acknowledged to get a sense of, who they were and how they helped. Can we do that?
JB: With pleasure.
HS: Burt Kotler
JB: First and foremost, I was just chatting with him via Skype yesterday. Burt Kotler was and has continued to be my closest collaborator, in many ways. Jokingly, one of Burt’s of my goals is to see if we can publish more papers together, as a team, than any other ecological team. Now, we don’t know how to measure this. This is, purely, a vanity sort of thing. There’s Houston and McNamara, a very famous team of ecologists that have published a lot together. Our advisor Mike Rosenzweig has published just a huge number of papers with Zvika Abramsky. Burt and I are, I think, 50 plus papers and counting.
HS: What about the Grants?
JB: Oh, that’s true. Absolutely. Grant & Grant may beat us hands down. I don’t know. But anyway, there are these awesome teams. The one thing I can say, although sometimes our wives wonder, I’m not married to Burt. When I entered the lab, Burt was one of the senior graduate students. He was going to be finishing up within a couple of years. So, he was there for less than half of my graduate program. But he had a very strong influence. Several features of Burt were, in hindsight, absolutely essential throughout my career. Burt was doing desert rodent ecology in Nevada as part of his PhD, and he was intensely interested in the role of predation risk in structuring desert rodent communities. And, in fact, he has a very key paper published in Ecology in 1984. And what he did was, he would put out trays of seeds, not buried in a substrate. He would put them in the open and under bushes just to see which rodent species he attracted. And then he also hung out lanterns to simulate moonlight. He actually ran around his study site and hung out kerosene lanterns, to see the effect of illuminating the grids. He was able to show a strong role of predation risk in structuring rodent communities. That had a huge impact on me. Second, his study showed me that you can go out and feed the rodents. The third feature of Burt that was absolutely formative is I consider him to be one of the finest experimentalists. His superpower is the ability to understand a theory and translate it into very simple, elegant and doable experiments. He is so gifted in that regard. I’m just in awe. And then he has another attribute that many of us don’t have, and I don’t have nearly as well as Burt. When Burt has an idea that he wants to act upon, he does it. I’ve got a whole pile of good ideas that I will do tomorrow. But tomorrow never comes. Burt was absolutely critical in terms of inspiring me by what he did. He also, very quickly, appreciated the value of giving up densities in food patches. When he saw the food patches in action, I think he grasped their significance, either as easily or perhaps even more easily than I did. He was the one to say, wow, wouldn’t it be great if it was possible to actually, in a more controlled situation, study the effect of owls and cover on foraging behavior. And then I was just musing, and I said, well, when I was an undergraduate, this guy William Wirtz, ran a raptor rehabilitation center and had an aviary. Burt was all over it. He said, we’ve got to use it; we have to do experiments. And so, there was a period where I wasn’t using my food patches at my study site. So, we packed up all the food patches, trapped a whole bunch of kangaroo rats and pocket mice, drove all night to California, and housed them there in California. Bill Wirtz was wonderful. He facilitated our research. He gave us access to the aviary, access to great horned owls and barn owls for the experiments. We eventually published two papers, and those are the papers that have William Wirtz’s name on them as well (1 & 2). That actually began, what continues even today, our interest in doing these types of aviary experiments. Burt now has a lovely aviary. He’s now at Ben Gurion University in the Negev in Israel. He’s got an amazing aviary setup in which we, as we speak, have continued experiments of that sort, of manipulating the rodents, the resources, the habitat, and then being able to manipulate snakes, foxes and owls. So, his interest in very sharp clean experiments and his willingness to push me to do it continues right up to this very moment. When I finished my PhD, he was a young assistant professor at Ben Gurion University. So, he encouraged me to apply for a postdoc there, and I got the postdoc. So, I spent a postdoc year, in 1986 to 1987, working with Burt, both, doing field experiments and aviary experiments, and continuing to develop using giving up densities and food patches. As I said, Burt recognized the opportunity to advance the types of interest in science he wanted to do. In my 30 year career at UIC, I generally go to Israel once a year or once every two years, and we continue our collaboration.
HS: The next name on the list is William Mitchell.
JB: Bill Mitchell was a graduate student one year ahead of me. And he was also incredibly formative, certainly early on, in my career. Bill Mitchell’s superpower was, even as a grad student, he had just an unbelievable grasp of the philosophy of science. Also, he is a superb theoretician; he did optimal foraging theory. Bill and I grew up together, we defended our PhDs on the same day, we went to Israel and we were postdocs together with Burt at the same time. How is that for shared destinies! Bill taught me a lot of optimal foraging theory. He wrote a paper with Tom Malone, titled The Optimization Research Program published in The Quarterly Review of Biology in 1991. It was very much a defense and an extension of how an adaptationist research program can be applied. Lewontin and Gould had published their paper on The Spandrels of San Marco, and that had left a lot of the field in a bit of conceptual disarray. And Bill Mitchell and Tom Valone, in a very incisive paper, really clarified the issues on how one should appropriately apply an adaptationist program. And boy, I drank their Kool-Aid! It was really a great paper and it inspires and motivates a lot of my research. And then finally, like Burt, Bill recognized the value of food patches and how they could be used. I still remember a lunch over which, Bill and I got interested in the question of functional responses and indirect interactions. We realized that these food patches could be used to investigate aspects of diet and aspects of functional responses. We also felt that it would be a new twist, theoretically, different from most functional response theory, which didn’t consider depleting resources. Bill and I, over a couple of lunches, hammered out some theory. We realized we could test it in my study site. During my fieldwork, my trays were in use, usually, seven to eight consecutive days a month, but the rest of the time they just sat out there. So, Bill and I designed a study, and, I believe, we collected seven days of data or less and published two papers. That’s Brown & Mitchell 1989 – Diet selection on depletable resources – and then there’s Mitchell & Brown 1990.
HS: Jean Powlesland
JB: That’s my life partner, my wife, she’s actually a nurse. She herself is not directly a scientist in any of this, but, oh my goodness, she’s been my lifetime companion and buddy. She loves to travel around and see these places.
HS: Sandra Rode
JB: Sandra Rode and I entered Mike’s lab together as graduate students. We were the newbies together. We became very close and fast friends because we could share and vent any of our issues with being newbie graduate students. Her role for me was being a friend and support. Her research actually went towards studying temperature sex determination in turtle eggs. Later, she veered towards museum sciences. She got her degree, eventually, in museum sciences and went on to have a career outside academia; a very, very successful career.
HS: Tom Valone
JB: Tom Valone was a graduate student that came later into the lab. He entered the lab, probably, two years or so after I did. He came very much with an optimal foraging background. He was very much interested in social foraging and information in foraging. So, he was primarily interested in working with birds. But because he was interested in information processing, he had read the various papers at the time, by Dick Green and a number of other authors that had written on how a forager should assess patch quality. There was a paper that had just come out by Yoh Iwasa and some colleagues in which they identified a variety of patch use strategies, if it were sort of a Bayesian forager, or a very clever forager. It was a purely theory paper. Tom had read this paper and had me read this paper and then asked, how do my rodents figure out how rich the food patches are? Up to that point, I’d just been putting out my food patches, each with three grams of millet, and I was simply interrogating the rodents month in and month out. But Tom Valone was asking, how do your rodents figure out what’s going on? So, we devised some experiments manipulating the initial abundance of food and seeing how low they forage the food. Basically, Tom’s brilliant idea was that you can actually get into the minds of the decision maker by looking at the kinds of mistakes they make. By looking at the pattern of mistakes, you can infer what kind of decision rules they’re using. So again, because my study site was out there – you’re probably already seeing a pattern to this – few weeks out of every month, my study just sat there. Tom realized the value of that study site. So, we manipulated the initial abundance of food to test between fixed time strategies, Bayesian strategies and various patch use strategies. That later became Valone & Brown 1989, and that became part of his PhD thesis, which was really great. Tom has continued to be a close buddy and colleague. He’s now at the University of St. Louis. He has a textbook in animal behavior. His research now is aimed at invasive species, more plant work than animal work, but Tom’s is an incredibly versatile scientist. Burt, Bill and Tom were the three that saw the value of what I was doing for shorter-term behavioral studies.
HS: Jim Brown
Jim Brown is awesome. A member of the National Academy of Sciences. My joke has always been, throughout the career, whether this is a case of Mullerian mimicry, where Jim Brown is the model and I, Joel Brown, am the mimic? I can go on and on with Jim Brown stories. I had the great pleasure of having Jim Brown on my PhD committee. He was absolutely selfless in giving me time and chatting. At that time, his office was virtually next door to Michael Rosenzweig’s office. He was generous with his time and generous with his insights. Later, right up to this day, he’s been generous when I’ve needed letters of recommendation. And indeed, there was mimicry! People would often confuse me with him. I remember once was at one of my first seminar invitations when I was at the University of Illinois. Some of the grad students, as they often do, had arranged to meet with me. And there was this one student who clearly wanted to do her homework ahead of time and wanted to be prepared. I sat down with her and she goes, wow, I’m so happy to meet you. I really like your paper, blah, blah, blah. I said, oh, what paper’s that? I’d like to talk about it. She said, the paper you did with hummingbirds. That was Jim Brown. Okay. I said, well, you’re mistaking me for Jim Brown. She looked terribly embarrassed, and you can see this look on her face that says, oh my goodness, what a terrible faux pas. But I turned to her and I said, look, Jim Brown was on my committee. I think he’s awesome. That’s a cool paper. Let’s talk about that! Another, Jim Brown story that I laugh at is when we were both speaking in the same symposium at a conference in Acapulco. This is now probably 15 years ago. We were going to be speaking back to back. I had not seen him for probably over a year at that time. I walked into the lecture hall, saw Jim, sat down next to Jim and then we looked at each other and realized we were wearing the exact same shirt! Anyway, Jim has been an inspiration and was a valued committee member.
HS: James Cox
James Cox was super important in my career in small but crucial ways. Given my interest in economic modeling, my PhD minor was economics. At that time, if you wanted to learn game theory, if you wanted to learn microeconomic theory, which was far more developed than optimal foraging theory, you had to go to economics. That meant that I had to have at least three committee members from Ecology and Evolutionary Biology and I had to have two committee members for my economics minor. Jim Cox was the chair of my economics minor. He was wonderful and was willing to take me on. At that time, Jim Cox was one of the most important movers and shakers in what was then called experimental economics. And experimental economists, or many of them at that time, because humans were unpredictable, were testing their ideas on pigeons and rats. They were essentially setting up foraging experiments for rats and pigeons to test contesting economic models. That was some of the stuff that Jim was doing, so he was a natural choice. The most dramatic and critical moment involving Jim was at my PhD defense. Jim had watched, with interest, the development of my patch use model. He probably understood the mathematics and the proof of the model more than any of my other committee members, because it was an economic decision making model with diminishing returns. Jim had a flair for the dramatic, which was good; he was also a sweetheart. And I’ll never forget – boy, did my life flash before my eyes – at my PhD defense, during the closed door portion, he asked me to identify all the key steps and assumptions I was making in my proof, of what later became the 1988 paper. And then he pointed out a variety of features and said, do you need these assumptions? Indeed, I did not. And then he goes, to meet these assumptions, do you have a proof? I said, I don’t. And of course, at that point, I was sweating. The rest of the committee was like, oh my gosh, the centerpiece of my dissertation was now hanging in the balance. And Jim Cox, once he had created his drama, and created this dramatic moment, he then walked me through a much simpler proof. So, he had obviously read my thesis, saw my proof, saw that my proof was way too baroque, way too involved, and plus, it actually made both unnecessary and incorrect assumptions. And so, the actual proof that is in my 1988 paper represents a correction that Jim Cox suggested.
HS: Robert Holt
JB: Bob Holt was the outside member of my PhD committee. He was wonderful. In his own PhD, he had worked with apparent competition. He was very much interested in these kinds of indirect interactions. He had begun working on how behaviors could influence these types of interactions. And so, Bob’s work, and what he continues to do, has always been an inspiration. I met Bob Hall via Burt. Bob Holt was Burt’s outside committee member for his PhD. Burt then went and did his postdoc with Bob Holt. So, you are starting to see a very inbred family! And Burt and Bob published a very important paper on short-term appear competition in The American Naturalist that parallels and helped inspire the stuff that Bill Mitchell and I were doing. Bob Holt, throughout my career, has been an inspiration. He’s been a close friend. He’s somebody I admire, and his work, in many aspects of what I’ve done, has been crucial. And he too has been generous in writing letters of recommendation for me.
HS: Thomas Vincent.
JB: Tom Vincent was an aerospace mechanical engineer. He was very, very interested in Game Theory. Actually, his area of expertise was missile guidance systems, something that is in the news these days. I met Tom when we had Maynard-Smith come and give a seminar in 1981. Maynard-Smith, very kindly, allowed one of our faculty members to use a preprint of his Game Theory book, his 1982 Game Theory book, in a seminar class on evolutionary Game Theory. I loved Game Theory but I didn’t understand it. So I went to the instructor, Richard Michod, and said, look, I’m really interested in Game Theory, but I don’t really understand this. Rick Michod – boy, I will bless him forever for this – said, you know what? I’m a population geneticist. I’m not an expert in Game Theory. But if you’re really interested in Game Theory, this guy, Tom Vincent, over at Aerospace and Mechanical Engineering is the campus expert on Game Theory. I hauled myself over to the Aerospace and Mechanical Engineering building and marched up to his office. I was very nervous. I had no idea why this man would want to talk to me. I kind of blurted out to him that I was interested in Evolutionary Game Theory, that I’d had a little bit of training in Classical Game Theory, but I really don’t know how they fit together. Tom told me to sit down, catch my breath, relax; he was wonderful. He obviously could tell I was nervous. And he says, you know what, I have always wondered what the connection is between Evolutionary Game Theory and Classical Game Theory. And he said, here, read these papers and come back next week. From that moment until he died, in October 2009 of pancreatic cancer, Tom and I would meet weekly. As my career advanced and I moved away, we would have weekly phone calls if both of us were in the country. He continued to be my lifelong collaborator in developing and expanding Evolutionary Game Theory from simply matrix games within broader theory of coevolution, macroevolution and microevolution; what is now known as adaptive dynamics. And so, Tom Vincent was kind of my co-advisor and was my parallel life. We published a book together in 2005 on Evolutionary Game Theory. We published a lot of papers together developing Game Theory. Tom really was the person that created for me my parallel world of Game Theory. It was nice that these worlds developed pretty much independently. However, much later in my career, in terms of predator-prey, ecology and fear, predator-prey foraging games, these two worlds then finally united. Tom was also instrumental in the next move of my life right now, more than he can know because he’s dead now, sadly. He developed a collaboration with a radiologist at the University of Arizona on Evolutionary Game Theory in cancer. Tom Vincent and Bob Gatenby, essentially, are the fathers of applying Game Theory to cancer. They published six or seven papers during the period of 2003 to about 2008. And throughout all that time, Tom Vincent worked really hard to match make me with Bob Gatenby. He said, you’ve got to join us, you’ve got to work with Bob, you’ve got to work with me, you’ve got to work with us on cancer, And being somebody who spreads myself too thin, I said, look, I’ve read your papers and it’s great. I love this application of Game Theory. But you don’t need me and plus I’m too busy. But in 2008, in a Game Theory conference in Poland, Bob Gatenby, Tom Vincent and I were sitting having a beer together, and I finally said, I’ll join; this sounds great. We actually outlined our first paper together, published in 2009, on a napkin in Poland over this beer. Then Tom got home, saw a doctor – I didn’t know at that time – calls me up and says, I’ve got terminal pancreatic cancer. At that point, I said, look, Tom, I completely understand if you’ve got better priorities. I can’t imagine what this does. I can’t imagine how this affects you. I said, look, if our work doesn’t seem important to you at this point, I completely understand. But, in fact, Tom’s reaction was he wanted to redouble his work on Evolutionary Game Theory; particularly cancer. And so, Bob Gatenby, Tom and I would have weekly calls. Bob had, by then, moved to the Moffitt Cancer Center in Tampa, Florida. He invited both Tom and me there in early 2009. Tom gave his very last seminar, on Evolutionary Game Theory in cancer, in January 2009 at Moffitt. I got to witness his seminar. It was Tom’s last lecture, like that book The Last Lecture. He died in October. But Tom had bequeathed me Bob Gatenby. Bob and I continued to have weekly phone calls, he has become my closest colleague, and I now work almost completely on cancer. In fact, because of this association, on 31 December I retired from the University of Illinois in Chicago – I’m now emeritus there – and was hired by the Moffitt Cancer Center. As we speak, I’m actually sitting in my new office, as of January 3, at the Moffitt Cancer Center, applying foraging theory and Game Theory to cancer.
HS: David Vleck
JB: When I started the University of Arizona, David Vleck was a new assistant professor in the department. He was a physiological ecologist, and he taught courses on physiological ecology. His research interest, at that time, was the cost of burrowing. He was doing anabolic measurements of the cost of burrowing in pocket gophers. But he was also beginning to shift his research interests to looking at a species of lizard that lives in the mountains – Sceloporus – that has live birth. It comes closest to having something like a placenta. It is truly viviparous; not ovoviviparous. He was beginning to study their physiological ecology because these lizards live in very, very cold temperatures, sometimes below freezing, up on this mountain, and they come out and sun themselves on black rocks during the day. He was studying how these lizards can use solar warming to keep themselves warm and to internally then develop their young. Cool species. David was a young faculty member who, obviously, didn’t have a big lab at that point, in terms of graduate students. He was always phenomenally generous with his time and ideas for the graduate students. In the process of getting to know Dave Vleck, we learned a few things about each other. He also came from Pomona College, but he graduated before I went to college. He too got his interest in ecology working with Bill Wirtz. I didn’t know that at the time. It turned out we were academic sibs via our graduate advisor. Third thing we learned about each other: we had both learned from William Wirtz to noose lizards Dave had been trained before me; I was trained years later. Dave Vleck was wonderful. He needed a research assistant to work on his new lizard project, who could cross-country ski and who could noose lizards. So, he hired me. That was just a wonderful year of being his research assistant. I learned a lot from him. He was also on my committee, along with Mike Rosenzweig, Jim Brown, Jim Cox and Tom Vincent.
HS: Do you have anything more to add about Mike Rosenzweig?
JB: Mike is an exemplar of how science should be done. He had this ability to balance being hands off, letting us make our own mistakes and be independent, but also being able to kind of scoop us up and direct when we were going off a cliff. I would truly say he’s an evolutionary ecologist. And I define evolutionary ecology as studying ecological systems through the adaptations of the organisms. In this day and age of genetics and phylogenetics – all very exciting stuff – we often forget that the third leg of natural selection is fit of form and function. We often forget that it’s the fit of form and function where evolution meets ecology. Genetics is the recipe of inheritance. The phylogeny is a description of where these things evolved from; their tree of life and their history. Mike was the inspiration, and continues to be my inspiration for how can one then apply ideas of fit of form and function to understand ecological communities. As you saw, he neither required nor sought out his grad students as collaborators. Over time, he formed some collaborations, and they were truly collaborations, where we have mutual interest, either together or through other colleagues. I’m really proud of a paper we had in 1987 that has Mike Rosenzweig, Tom Vincent and myself, about a set of ideas that conjoined Red Queen Evolution, which Mike was interested in, with a game theoretic approach. To me, it was just really cool. It had nothing to do with my dissertation, nothing to do with anything other than our joint interests. He was the inspiration for Burt to be able to go do desert rodent ecology in Israel. Mike, through his collaboration with Zvika Abramsky, now a retired emeritus professor at Ben Gurion University, really set the foundation for Burt’s and my collaboration with desert rodents. So, in the same way, that Tom gave me Bob Gatenby and cancer biology as his inheritance, Mike really gave Burt and me all of our work on desert rodents in the Negev as his inheritance to us.
HS: Hubert Markl
JB: You know, I’m embarrassed to say I don’t know who that is!
HS: You thank Hubert Markl for scientific and editorial comments.
JB: Oh, I think he was the associate editor on the paper. Yes. Oh, yes. I’m indebted to him. He was the corresponding editor. As a graduate student, I wrote badly, I conceptualized things badly, but he was willing to see the diamond in the rough, and really helped turn the writing into something sensible.
HS: Did you continue to work in this study site after this study?
JB: No. I used to joke that the study site had a sign in front of it that said, ‘behind this sign lies the industrial future of Tucson’. My joke is that nobody can replicate my study and my study site, because much of it is now warehouses, factories and even some housing developments. Tucson has continued to grow. I was just out in Tucson last week for the festschrift for Mike and I did swing by my study site. I’ve done that a couple of times. There are still big chunks of lovely creosote flat; probably have the same rodent species. But now, Tucson has encroached on my study site.
HS: When did this happen?
JB: I think it was a slow process. I know another grad student, Barbara Harney went out there and actually took advantage of it to do some field work because we knew a lot about that site. I know, within about five or six years, I could still go out there, and I was embarrassed to say even find some of my food patches that I forgot to clean up and pick up. I suspect it’s been a gradual process, but I guess you’d have to explore a series of Google Maps to sort of see the general encroachment.
HS: Do you still have the trays that you used in 1988?
JB: I hope they’ve all been recycled. I used at the time, as a poor, starving grad student, collect aluminum cans and then send them to the recycler. Since I had made the trays out of aluminum, I recouped a bit of my costs when they would get all bent up and start to tear when I actually wound up taking them to the recyclers. I don’t believe any of them still exist,
HS: Do you do similar experiment now or in the recent past, using aluminium trays and millet seeds?
JB: Oh, in my lab, in my own work, we continue to use millet. It is just the perfect standard. We’re doing house sparrow experiments in my backyard using millet and sand. That’s exactly what we still use in Israel. However, we’ve graduated to those fine high quality plastic trays that are now available inexpensively. At the time I was doing this work, you either had terracotta trays, which were very heavy, or you had plastics, but plastics at that time were really shoddy and they tended to photo-degrade. But nowadays, if I was to do it over again, there are these wonderful plastic saucers you can buy all over the place that work just great.
HS: Towards the end of the paper, you identify potential problems in using this approach of manipulated resource patches: patches are not natural; resource provided maybe inappropriate; foragers may become satiated; trays may be visited by more than one forager. In subsequent work, did you find ways of getting around these problems?
JB: Yes. What’s happened, which is actually very gratifying over the years, is that, not only did we find ways to get around the problems, we could use the problems for additional investigations. For example, nowadays by combining “smart seed trays”, using pit tag technologies, using camera traps now, you can get around the problem of multiple foragers of different species. You can actually identify the individual. Back then all I had was footprints.
You can also do things like keep increasing the amount of food you’re putting out there and find out, actually, when the giving up density begins to go up. You can actually then use changes in giving up densities as a way to find out at what point you are satiating. Often now we’ll put out an assay tray, a tray that has just a fixed amount always, and then we may use a bunch of trays to create a manipulation of state, for example, by drawing the foragers into risky surveys. I would say most of these issues remain important issues, but they actually create, with the appropriate experimental design, ways to go. And if I can kind of make a plug – I had nothing to do with it – there’s a great paper that came out of Peter Banks’s lab and Claire MacArthur’s lab a few years ago, where they really nicely revisit many of the methodological, procedural and intellectual challenges of using food patches and giving up densities. It’s just a really clear exposition of many of the issues that were first raised at the back of this 1988 paper, and many of them get answered and addressed in that paper
HS: Did you use the phrase “giving up densities” for the first time in this paper?
JB: Yes.
HS: Do you remember if you considered other names?
JB: At that time, it was kind of fun. The phrase “giving up times” was popular in the foraging literature. Foraging biologists were to get at diminishing returns was to measure the time between getting a food item and abandoning a patch. In a sense, they were creating a very similar construct around giving up times. That provided the evolutionary jump off point for our phrase. In this case, since one was imagining harvest rate being a function of some abundance or density of food, giving up density was just a natural fit. So, in a sense, it wasn’t really a unique creation. In fact, for many years – 5,6,7 years – before this became entrenched in the literature, people would often confuse giving up density and giving up time.
HS: How has your thinking about this concept changed today, both in terms of the theory and the methods you use to measure it?
JB: Giving up density, at least in terms of patch use, still provides, for me, a unifying concept or approach or metric that unifies theory and practice. I guess what has happened over the years, which has been exciting, is to see the connections between giving up densities and Tilman’s R*. I saw the connection but never sort of formalized it. Giving up density really draws attention to the notion of what you can tell with margins. But then a lot of other theories operate on what you get from averages. Part of the elegance of the Marginal Value Theorem was that the margin equals the average. The fitness of animals is a function of their average intakes of things, but their decisions are made on the margin. What is interesting, and continues to be interesting today, is how can you use a measure of an animal’s marginal perceptions to gain insights into its average state. Another really quick and obvious thing that jumped out from giving up densities that became important was that animals are not just allocating time. They can use vigilance and apprehension to shift their approach to a food patch. I’d naively assumed that the foragers simply have a gain curve or some sort of fixed harvest rate based on the abundance of food in the patch. Clearly, that’s not the case. They can adjust how apprehensive they are. Those became, kind of, important extensions. Ola Olsson came along and showed that Tom Valone and I were actually wrong in the way we conceptualized Bayesian foraging. And once he pointed out we were wrong, we could ignore him, hate him or hire him as a postdoc. He came and postdoc-ed in my lab, we extended the theory of patches to truly include Bayesian foraging and what it means. He’s brilliant and we’ve continued to collaborate. I guess for me, it’s all been kind of a fun sort of evolution and it’s still immensely relevant. I would love to measure the giving up densities of cancer cells in tumours, on glucose, glutamate or oxygen. So, it still looms very, very large. Every time you watch someone chew on a chicken bone you get to watch giving up density. Every time I see my daughters leave way too much food behind on their plates, I get to see you giving up densities
HS: If you were to redo this study today, would you do it differently?
JB: Oh, absolutely. There are so many things about this study that was goofy. There are methodological issues. I constantly randomized the positions of the trays each month across my stations. And my reasoning for doing that was I felt that I might get a random sampling of the rodents… I don’t know what I was thinking. I just thought it was a better experimental design. In hindsight if I had kept my trays in fixed stations every month, I could have learned a lot more about space and time on these rodents. I ran these things 7-8 days a month for 15 months, and at the end of it, I had well over 10,000 data points. In hindsight, I wound up with way too much data, and it turned out, I wound up with much less data than I needed on certain targeted things. I should have been paying a lot more attention to stratifying the data. At some times of the year, kangaroo rat data was a dime a dozen, but pocket mouse data was a bit more challenging because the kangaroo rats were getting to all the trays. Obviously, I would have loved to have the more modern technologies and whatnot that are now available to us. I was so fixated on getting an avalanche of data that would demonstrate my point, which I got, I wasn’t biased, I collected my data and I stuck to my regimen, a lot of it was probably overkill. And, I don’t know, this is a hard one to say in hindsight: thanks Bill Mitchell, Tom Valone and Burt Cutler, they were very quick to spot the value of doing short-term manipulations. I think, in my overall data collection, I was probably too much of a purist. I was happy to collaborate with these cool people outside of my regular data collection, but never integrated it into my data collection. In hindsight, I probably could have done more manipulations that were directly relevant to my work. I guess, in one way, I wouldn’t change it because it taught me a work ethic, I learned a lot tangentially, it got me out there all the time. If I had done it better, I would probably wouldn’t have had to go out more often. If I had done it better, I might have just missed what happens when you do overkill.
HS: The data in this paper was collected in September 1983 on seven mornings and afternoons. Did the rest of the data go into other papers?
JB: Yeah. What was interesting was getting this published was a tough slog. I finished my PhD in 86. I think the first time I submitted this paper was probably 1985, after all my data had been collected. It got tossed out of Ecology. I think it may have gotten tossed out at The American Naturalist. It fished around. And I think it was getting rejected for a couple of reasons. One is I probably didn’t write it nearly as well as I should have. That’s my problem. And the other is, as you know, sometimes getting this sort of stuff published is really hard. There just wasn’t really an appreciation or view that there is a need for it. I remember an interesting dilemma. At that time, we subsequently had data from Burt from the aviaries. We had this work with Tom Valone and Bill Mitchell. I remember being worried that, oh dear, this will be terrible. What if these other papers get published before my paper that’s supposed to identify the technique? Won’t that be terrible? I will lose my thunder… anyway, I use this as a story for my grad students when they worry about this thing. Eventually, it didn’t matter at all. It was great. I got so frustrated with trying to get it published, I was already a young assistant professor at UIC, so I just sent it off to Behavioral Ecology and Sociobiology and it got published. But that same year, work that was done two years later, got published in Oikos, Oecologia – that was fine – the stuff with Bill Mitchell came out very soon. So, the lovely part is, in hindsight, it didn’t really matter in what order these things were getting published or not. My fears were all unfounded, but it was tough getting that published.
HS: Do you remember when where and when you did most of the writing?
JB: I, obviously, wrote it up for my dissertation. And then was writing it up for publication must have been in 85. Most of the submissions and rejections probably happened while I was in Israel on my postdoc in 86 and 87. Also back then, it could take a long time for these things to get published. I think the final final review and acceptance was when I started my position in 1987 at UIC. But I don’t remember it very well; I would have to go back and check.
HS: At the time it was published, do you remember how it was received? Did it attract a lot of attention?
JB: Um, you know what, I don’t think initially it attracted much attention at all. Among the desert rodent people, there are some individuals that were highly skeptical and others who jut said no. Generally, the reaction was this is too easy. The feeling was field biology or mammalogy can’t be that easy; if it’s too easy, something’s got to be wrong. You often see that current in ecology that if it’s really complicated, it must be right. And then of course, the corollary of that is if it looks easy or simple, it must be trivial or unimportant. And so, it was kind of a slow going, initially, in terms of getting accepted. But I guess to turn it around, what was nice – as Burt and I point out about his lab and my lab – was that we essentially had 10 years where we had the whole intellectual space to ourselves, to explore different ideas, different systems, different questions. There were other individuals like Bill Mitchell, Tom Valone and others, who were colleagues and associates and who used it. Zvika Abramsky picked it up very quickly and used it in his work in Israel. So, there were some people I guess you might jokingly call early adopters. But the main thing I think, which is good news, is it proved useful. And it became for others a useful technique. For me, it was a big motivation, something important for my sense of connecting concepts to ideas. For me, food patch use and giving up densities is much more than a technique. It’s been a lot of my intellectual development and my intellectual work. But for everybody else, it should be a technique that they should use when it’s useful and a technique they should discard when it’s not useful,
HS: Over the years, have you been surprised by how much it’s been cited, and do you have a sense of what it mostly gets cited for?
JB: I think it generally gets cited for multiple things. One is it gets cited by people who are using the technique, which is great. Sometimes I think it gets cited as a measurement or as an indicator of habitat differences and prediction risk. And then I think it often gets cited, when people are doing sort of smorgasbord experiments and they’ll either now cite it as, we did a smorgasbord experiment but we did not get buried in the substrate, and then they’ll cite my work, or they’d say, we did a smorgasbord experiment and put in a kind of substrate, and we think we’re getting results that are kind of concordant with Brown 1988.
HS: Would you say that this paper was an important landmark in your career?
JB: Oh, absolutely. It established for me what has been a lifelong interest in connecting theory with experimental work. This patch use model, the ability to use patches by choice habitat selection, the centerpiece of foraging theory, really then has been the canvas on which we could then rattle off equations, and then use this technique which has proven to be a very simple and fast way to test some of those ideas. It’s been expensive. It’s been great for my grad students that are waiting to get funding. We can always make up an inexpensive food patch experiment. They’re really useful in developing countries. I’ve had grad students come from developing countries, and they often don’t have access to the coolest techniques and technologies. In terms of technology transfer, this is probably the easiest one of all. So that’s been kind of gratifying. The second feature that’s been important is it allowed me to join and participate and be seen as a foraging biologist or foraging ecologist, and eventually work with Ron Ydenberg and Dave Stephens on our edited volume on foraging. The three of us, with all of our different facets of foraging, recognized the value of each other’s approach and Dave Stephens was our fearless leader. So, in that sense, the work I did allowed me to get recognized and established in the area of foraging ecology.
And then, I suppose I’m very proud of this, but also humbled at the same time, really thanks to Burt Kotler and the cool committee and people at the American Society of Mammalogists, last year I was awarded the C. Hart Merriam award in Mammalogy. That’s really thanks to my colleagues, and I’m very humbled in that sense, but clearly, what would allow them to even consider me for the award is my work in mammalogy, and this technique of giving up densities. That technique eventually led to the ecology of fear, the other area that I’m known for in ecology. If it weren’t for giving up densities, if it weren’t for seeing differences in foraging between safe and risky habitats, I don’t think I would have gone on and connected Game Theory with predation risk and developed, along with many, many other really cool scientists, this area that is now known as the ecology of fear.
I want to make one addition here. This is just sheer joy. I love to travel. I’m a culture junkie. It turns out that making a successful food patch turns out to be surprisingly tricky for some organisms in some systems. It can take a lot of work and perseverance. It also takes a lot of experience. So, often it’s not obvious how to manipulate a food patch that isn’t working. One of the things I really enjoy, which I now get to do more often, but I never anticipated this, is I occasionally get invited by cool people to come to their study site to develop a food patch. Patrick Jansen realized it’d be a lot easier to bring me down for a week to Barro Colorado Island in Panama to develop a food patch for agouties, these funny big rodents, than it would be for him to develop it. And indeed, in a week I could make a food patch. I was invited a couple of years ago to go up to Alaska to develop a food patch for Arctic ground squirrels, because I can generally do it faster and identify when it’s working when it’s not working. A colleague of mine, Dave Scheel, at Alaska Pacific University, kindly invited me out for a week, a couple of years ago, to develop a food patch for octopus in Prince William Sound. A number of times now I’ve been invited to very, very fun places, specifically, to make a food patch. Sometimes, this then develops into additional collaborations.
HS: Have you ever read this paper after it was published?
JB: A couple of times going way back I have read the paper. I don’t think I read it from start to finish, but I’ve read it to, both, verify accuracies and inaccuracies to kind of see how did I frame the marginal rate of substitution. I did some work of expanding the theory and clarifying aspects of the theory in 1992. I had to definitely go back and read it in 1999 when I published a paper integrating vigilance and giving up densities, combining vigilance theory and giving up density theory. I think, at that point, I went back and read the whole paper just to ensure that what I was citing and referring to wasn’t fantasy. I’ve gone back and reread it because my memory can fade; my memory can be very shifty at times.
HS: Would you count this as one of your favorite papers?
JB: Oh, absolutely.
HS: Why?
JB: First, it gives me a warm and fuzzy feeling because this was when I, finally felt I was having some reasonably novel ideas. I caveat ‘reasonably’ because anytime we think we have a novel idea, only about two or 3% of that is probably really novel. I guess it was at that point as a graduate student, where I had the joy of feeling like I was doing something that somebody else couldn’t immediately do. I had a place. I could be a useful servant to the academy of scientists. Seeing how my colleagues and friends and people I don’t even know have been able to run with it and do things I couldn’t even imagine and build upon it in ways that are far more creative than I could do. It was just very, very exciting. Also, the fact that it’s a paper I still need to cite and use in the work that I do now.
HS: What would you say to a student who’s about to read this paper today? Would you guide his or her reading in some way? Would you point them to other papers, they should maybe read along with this. Would you add any caveats to their reading?
JB: I think my advice to any student, first off, would be to read it, both, for inspiration but also for context. In some ways, you’re reading an antiquity. Within that context, read it as the first paper that launched a field. That’s always a good idea. Also, be prepared to be disappointed. Often, the paper that launches a field is: a. never intended to; and b. often isn’t written very clearly or isn’t written in a way that is accessible. In reading it, you might think, it could be written much better, the figures could be so much cooler, and so on. Then my advice would be to read that Bedoya (Bedoya-Perez) paper of the labs of Claire MacArthur and Peter Banks. That is a must read. And now that there are so many papers, my advice to students is to select the papers that represent the taxa that they’re interested in. So, if you’re trying to do desert rodents it is pretty easy: sand and millet still work just great. But I’ve got a student who’s doing coral reef fish. So, if one’s trying to do unusual food patches, then you want to read papers that have come up with very clever and unusual food patches. If you’re doing good numbers, perfect numbers. Rodin’s it’s pretty bread and butter. And then what question is one interested in? If one’s interested in community ecology, then I steer them towards Kotler & Brown 1988 in Annual Review of Ecology and Systematics, to get ideas on how this stuff can be applied. If they’re interested in conservation biology and management things then I would steer them towards a couple of papers that Burt and I have that deal with management issues (1, 2 & 3). If you are interested in multiple tradeoffs, read Claire MacArthur’s and Peter Banks’s awesome work. I’d use the 1988 paper as a place to get the historical entrée. Read the Bedoya paper to get a sense of what you can do and how it’s going to be hard. And then explore, a rich literature from my own associates and from other people, once you have an idea of the application you’re interested in.
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