12 Why lizards?
My biology life began with birds. I imprinted on them in January 1966 right at the start of the Natural History of the Vertebrates course (Zoology 113) at UC Berkeley. Birds were already active and conspicuous on our Saturday morning field trips in the Berkeley Hills, whereas lizards wouldn’t become active for a few months. Moreover, Ned Johnson, who gave the ornithology lectures in the course, was an engaging lecturer and an outstanding naturalist. [Partway through that course, Ned hired me as a research assistant to make sonograms of songs of Empidonax flycatchers.] And birds are fascinating visually, aurally, and biologically – no doubt about it. But time and some serendipitous field experiences would eventually convince me to study lizards.
By the end of Zoology 113, I was a ‘budding birder.’ I had thoroughly enjoyed my field project on the foraging behavior of Great Blue Herons (Chapter 10). Even so, I was still expecting to go to medical school and thought of birding as a future hobby.
I graduated the following January (1966). My Father was a petroleum geologist and was then working in Tunisia. His company would pay for my travel expenses to visit. So I hatched a plan to fly to Tunisia after graduation, spend a week or two with my parents, bum around Europe until late summer, and finally settle into the rigors of medical school in the autumn.
My plan was appealing but had a flaw – potentially a fatal one. This was the Vietnam era, and I would need permission from the Draft Board to travel overseas. Late in the fall term, I wrote the Board and explained that I was graduating in January and was expecting to start medical school in September. I then requested permission to leave the country between graduation and med school. The Draft Board’s answer was unexpected and unwanted: if I stepped out of school – even if I had already been accepted to medical school – I would immediately become draft eligible.
Europe was suddently and abruptly out. I urgently needed to find some way to stay in school for the spring semester. Larry Wolf, who had been the head TA for the Natural History course, told me about the Fundamentals of Tropical Ecology course in Costa Rica (starting in January), run by the Organization for Tropical Studies (OTS). The timing was perfect. The OTS course would not only postpone my vulnerability for the draft for at least two months but also give me an immersive field experience in tropical ecology. Taking that course might make up for my not going to Europe. I was still leaning towards a medical career, but I appreciated that the Tropical Ecology course might help me decide whether to switch towards a career in biology.
I had never taken an ecology course at Berkeley and so I was lucky to be accepted into that course (I’m sure Larry’s support helped). I flew to Costa Rica in January 1966. After a few days of orientation lectures in the capitol (San José), we traveled to Guanacaste, a dry-forest region in northwestern Costa Rica. Each day, we’d split the class into small groups for exploratory walks in the morning. We’d regroup for the afternoon lectures and biodiversity labs.
On our first morning walk, the already legendary Dan Janzen led my group. We followed Dan around in ‘his natural habitat,’ trying to learn the names of the many plants and animals we saw. Dan introduced us to the enormous and colorful Tabebuia trees, the enthusiastic howling of howler monkeys, and an overwhelming diversity of insects. We tried to absorb Dan’s extraordinary knowledge of and insights into tropical natural history and ecology. At that, Dan had and has no peer.
We’d all read about tropical diversity, but seeing, smelling, hearing, and touching (or being stung by!) that diversity all around us was overwhelming. Morning One in Guanacaste is etched permanently in my memory.
By late morning, we were hot and tired, and we began working our way back through the forest to the vans. When we approached a small stream in the forest, a large (~ 2 ft long) lizard suddenly and explosively bolted from the bank in front of us, sprinted across the top of the water, and escaped on the far side. I was caught off guard but said reflexively, “Jesus Christ! Look at that!”
Dan responded: “That’s what they are called, Jesus Christ lizards.”
Not being a lizard aficionado, I had never heard of these lizards. Dan explained that these lizards (Basiliscus) have large, partially webbed feet, enabling them to sprint across the surface of the water without sinking.
That was my first encounter with lizards during the course. In retrospect, I now realize that the sheer surprise of that event – plus the lizard’s athleticism – helped prime me for what was to come later. This was Step One on my conversion to lizard ecology.
The two-month course progressively opened my eyes to the tropics and to ecology. Every five days or so, we’d move to a new site and thus gain exposure to more of the breathtaking diversity of habitats and organisms in Costa Rica. Once at a new site, we’d have morning walks to learn some of the plants and animals and the ecology of the habitat. In the afternoons, course faculty lectured about some topic in tropical ecology or ran identification labs for plants and animals. Dan Janzen gave one of those lectures, and it changed my thinking and career (Chapter 29).
All OTS students were required to do a short-term field project of our choosing. I was still a confirmed birder and decided to study foraging of pelicans at Playas del Coco on the Pacific side. Pelicans were diving just off shore, and I could sit in a comfortable chair in the open-air bar of the local restaurant and record whether the divers were successful. I immediately liked the logistics, as they appealed to my slothfulness (Chapter 40). No need for me to beat through in the bush searching for inconspicuous birds because the herons at Playas del Coco essentially came to me, sitting comfortably in the shade of the open-air bar.
I could tell whether a dive was successful (a pelican that caught a fish would jerk its bill upwards and then visibly swallowed the fish in one gulp). I could also tell whether the bird was an adult or a juvenile, as the feather colors on their heads differed.
I soon accumulated lots of data by recording the success and age group for each diving bird, . The pattern was obvious: adults were far more successful than juveniles. I didn’t find this surprising at all. Diving for fish must be a complex skill, and of course, adults should be more experienced and adept than juveniles. [I later learned this assumption is called the Fallacy of Experience.]
I wrote up my project and thought no more about it – everything I’d observed and quantified seemed obvious and uninteresting. But recall that I’d never before had a real ecology or evolution course, and I knew nothing about life history theory. Thus, I had no context to view my observations.
Fast forward to early December 1970, just after I’d returned to Austin from the Kalahari. Eric Pianka was teaching a course in evolutionary ecology, and I sat in on a few of his lectures. One was on life history theory. He talked about the evolution of delayed maturity, which seemed like a risky life history strategy simply because late-maturing organisms might die before breeding. What could then compensate for that risk?
Eric reviewed various hypotheses that might explain the evolution of delayed maturity. One hypothesis was that delayed maturity might be adaptive if juveniles hadn’t yet become accomplished enough foragers to gain the sufficient ‘surplus’ energy needed to reproduce.
I immediately sat bolt upright and realized that my pelican data were relevant. After class, I walked with Eric to his office and told him about my OTS data. Eric hesitated and then said that sounds familiar. He shuffled through a stack of un-filed reprints and pulled out a recent one from the journal Animal Behaviour. That reprint reported that adult pelicans at Playas del Coco were much more successful than juveniles, at least in the dry season. Gordon Orians (later to become a colleague and friend at the University of Washington) authored that paper, which was based on an OTS student project that he ran (late 1966 and in 1967). Whereas I was too ignorant to appreciate significance of the pattern, Gordon (later elected to the National Academy of Sciences, among many other honors) appreciated the life-history significance of these observations. And I suspect that some of Gordon’s adults had been “my” juveniles.
Lessons? Being ignorant about the knowledge base of a field before starting a project does have certain advantages. Most importantly, one doesn’t inherit biases of earlier workers. I was “blind” to the relevant hypotheses of life history theory when I recorded the pelican data, but that also meant that I was unaware that my observations on age differences in foraging success were novel. I reasonably assumed that differences in foraging success with age must well established in the literature, such that the patterns I observed must be “obvious and trivial.” Ignorance can minimize bias, but it can also mask significance.
We spent most of the two-month course at various sites in the warm tropical lowlands. At the end of the course, we drove to Cerro de la Muerte (“mountain of death”). The Cerro is the highest point on the Pan American Highway (3,451 m, 11,322 ft). After almost two months in the lowlands, I found the Cerro bitterly cold.
My group was assigned to do a short-term project on thermoregulation of a spectacularly colored lizard Sceloporus malachiticus. The adult males were an iridescent bright green. They were undeniably gaudy.
We would catch these lizards and (using quick-reading thermometers) immediately take their cloacal temperatures. We also measured the ‘critical thermal maximum temperature’ (the high temperature at which a lizard loses its righting response when flipped on its back – a standard index of heat tolerance). I was impressed that by basking, these lizards could achieve high body temperatures (probably mid-30s °C, or low 90s °F) in an environment that I found far too cold for comfort.
I already knew about behavioral thermoregulation from lectures by Dr. Robert Stebbins in Zoology 113, but this was my first exposure to it in the field. It was my turn to report the results of our project to the class. Peter Bartlett (a fellow student in the course) corrected me about something. Peter was not a member of our “malachiticus” field group but seemed to know what he was talking about. [I later learned that his thesis research was on the biophysical ecology of behavioral thermoregulation in lizards. His 1967 paper in Ecology with David Gates was a pioneering application of biophysical principles to ecology.]
In 2023, I tried unsuccessfully to contact Peter, hoping he would remember what he had criticized during my presentation. I suspect I’d committed a biophysical blunder. But at that time, I did not know that a field of biophysics existed. But Peter knew it well! Despite having been corrected by Peter, I still was fascinated to see behavioral thermoregulation in the flesh. This was Step 2 in my conversion to lizard ecology.
At the end of the course, a van we’d used had to be returned to UCLA, which had loaned it to OTS for the course. I was in no hurry to return to the States and jumped at the opportunity to drive back through Central America. I joined Lloyd Dunn (a grad student in botany at UCLA) on the long (5,500 + km) drive through Costa Rica, Nicaragua, Honduras, and México. Norm Scott (who was a herpetologist and a co-organizer of our OTS course) flew from Costa Rica to Mexico City with a pet anteater. We picked them up there. A few days later, we spent the night just south of the US border. Early the next morning, we started driving west along a section of Highway 2 where it skirts the border with New Mexico and Arizona.
This spring morning (probably mid-March) was warm and sunny. Norm suggested that we take a break from endless driving, stop the van, and look for lizards in the pristine sandy desert surrounding Highway 2. We stopped, and lizards were everywhere! Look left; there was a lizard. Look right; there were two lizards. Whiptails, horned lizards, leopard lizards, etc. I had never seen such diversity and bursting activity. The three of us ran around like kids. We’d catch and release a lizard, then go hunting for more. This was fun. We were atavistic hunters, and quite successful ones as I recall! I discovered that catching – as well as watching – lizards was primitive and exciting.
After an hour or two, we reluctantly got back in the van and soon crossed the border into Arizona. Somehow customs didn’t object to Norm’s anteater. Perhaps we didn’t declare it!
During that drive to UCLA, and continuing once I was home in Berkeley, I began to suspect lizards might be more amenable research subjects than birds. Lizards had many advantages. They were far more abundant than birds, so I could collect data more rapidly. They were more conspicuous (usually) than birds, which often flitted in and out of sight, high above in the canopy. And, unlike birds, lizards ‘slept in’ and became active only at a reasonable hour. In my mind, lizards were rapidly accumulating brownie points.
I was back in Berkeley by late March. I was not in school. I didn’t have a job. By now, I had lost interest in medicine and withdrew my applications to medical school. But in so doing, I made myself a conspicuous target of the Draft Board.
The inevitable happened. I soon received a dreaded 1-A notice from the Draft Board, indicating that I was now “available for military service.” I knew that an order to report for a physical would come next. I was psychologically lost. I’d just had an amazing set of experiences in Costa Rica and Central America and was excited about the eventual prospect of graduate school in biology. But before starting graduate school, I would likely spend two years in the Army, fight in an unpopular war, and possibly never come home. The only alternative I saw was migrating to Canada, as I was not a conscientious objector.
I was unhappy, frightened, and depressed. I could not see anyway out of the draft. In desperation, I sent a letter to the Draft Board protesting my 1-A classification on the grounds that I was employed in an ‘essential industry’ vital to the security of the United States. In truth, I had no job! I was trying to postpone the inevitable, even for a month or two. Those times were desperate if you had a 1-A classification.
Much to my surprise and delight, the Draft Board wrote back and asked when I had started to work. What? I couldn’t believe the Draft Board might be sympathetic to my bold and dishonest request. Ray needed a job, and he needed it now.
Before going to Costa Rica (fall 1965), I’d worked for Dr. Robert Stebbins, helping him with a lab experiment on lizards. Stebbins was the Curator of Herpetology in the Museum of Vertebrate Zoology (UC Berkeley), and he was respected as a great naturalist, teacher, and person. Fortunately, Dr. Stebbins had left me on the Museum’s payroll when I went to Costa Rica. And even more fortunately, he now had a job opening! Steve Arnold and Dick Sage were fellow undergrads at Berkeley, and they had been managing the herp collections for Stebbins. Both were graduating in June, leaving for a summer of fieldwork in Costa Rica before starting grad school the next fall (at Michigan and Texas, respectively). Moreover, Dr. Stebbins was about to leave for a sabbatical year in Australia. Thus, the herp collections would be without a supervisor for a year.
Dr. Stebbins told me that if I’d agree to manage the collections while he was in Australia (at least until June 1967), he’d re-hire me and write a supportive letter to the Draft Board. I said yes! I would have signed that commitment in my own blood had that been necessary.
Dr. Stebbins wrote the Draft Board, explaining that he would be on leave for a year and that I was the only person qualified to maintain this important collection in his absence. He stated that I had worked for him before going to Costa Rica and had now resumed my work. He didn’t mention that the new curatorial work was completely different from the lab experiment I’d worked on previously. His letter worked, and the Draft Board gave me a beautiful occupational deferment (“II-A”). Major relief!
[Looking back I deserved that deferment. Berkeley in the mid-60s was the world center of activist radicalism and protest. Someone needed to step up to the bar and protect the herp lab against potential invasions by pinko-radical-anarchist students (i.e., my friends). I was prepared to serve. I rose to the challenge. I would protect the collections. Note: I’m joking, of course.]
I spent the next year as the assistant to the Curator of Herpetology. The herp lab had a great collection of reprints, and I began reading through them when not involved with curatorial tasks. Had Steve and Dick – who’d been herpers since childhood – still been around, I would have learned a lot from them. But they were off to Costa Rica and then grad school. Fortunately, Ted Papenfuss and Jim Lynch were around. I spent time with both of them in the field. Ted is universally regarded as the best all-around herp collector in the world. There are no pretenders to that throne. Watching and learning from him in the field is always a privilege.
By the time Dr. Stebbins returned from Australia, I’d utterly given up on birds and saw only lizards in my future. Lizards were relatively easy to study and observe, and I was increasingly fascinated by their behavior and ecology. Moreover, my time with lizards in the MVZ saved me from being drafted – at least for one year. I took this as a sign.
The following summer, I was off to the coastal deserts of northern Peru with Carl Koford and two grad students. I was the ‘designated herper’ of the group, and I soon discovered geckos (Chapter 13). Thus began my career as an accidental herpetologist.
Why lizards? Looking back, I know that my transition from birds to lizards was not a result of a logical and well-crafted plan. Instead it resulted from a combination of unplanned and idiosyncratic events that sparked my interest: being startled by the Jesus Christ lizard in Guanacaste, being stunned by the ability of Sceloporus malachiticus to reach high body temperatures on a very cold mountain, the sheer fun of chasing lizards in a sandy desert in northern México, and by getting a museum job that not only delayed my eligibility for the Army but also gave me an opportunity to learn about herps and herping.
And the timing was just right. Lizard ecology was beginning to impact ecology and ecological physiology (see Milstead, 1967). Established herpetologists (George Bartholomew, Frank Blair, Bill Dawson, Ken Norris, Stan Rand, Rodolfo Ruibal, Don Tinkle, among others) had laid a firm foundation for the field, plus some upstarts (Bayard Brattstrom, Jim Heath, Paul Licht, Eric Pianka, Warren Porter, and Tom Schoener) were already studying lizards and rapidly expanding the boundaries of field ecology, physiological ecology, and evolutionary ecology. It was an opportune time to convert to lizard ecology.