My first meeting with Bill Duellman (Fig. 1) was on a sunny day in September of 1969. I was in my first year at the University of Kansas (KU). I had applied for a student job in the Natural History Museum on campus, and was called in for an interview by the curator. Duellman was an imposing figure at the time, just 39 years old, trim and fit from recent field work. After a few intimidating questions, I was hired. I had no idea how important a figure Bill was in herpetology.

Figure 1 William E. Duellman collecting tadpoles at Lago Perdido. Santa Cecilia, Ecuador, April 1972. 

William Edward Duellman was born in Dayton, Ohio, on 06 September 1930, into a middle-class family (his father owned an electrical wholesale supply company). Bill became interested in nature at an early age, was active in the Boy Scouts, and excelled at basketball and other sports. While in high school, he volunteered at the Dayton Museum of Natural History where he developed his interest in reptiles and amphibians. Around the time of his 17th birthday, Bill published his first paper, coauthored with the museum curator, John Thornton ^{Wood (Wood & Duellman, 1947}).

After graduating from high school, Bill enrolled in the University of Michigan in September 1948, and shortly afterward began working in the herpetology collection of the Museum of Zoology on campus. In a recent essay, Bill credited his professors (primarily Norman E. Hartweg, Laurence C. Stuart, and Charles Walker) and two older students (Herndon Dowling and James A. Peters) with teaching him the fundamentals of herpetology (^{Duellman, 2021}). Bill quickly became an active field collector in the United States, and made his first trip outside the country in the summer of 1951 to Michoacán to spend ten weeks as part of a survey team from the University of Texas. Bill often told stories about that trip, and wrote that “Most of the time the group traveled by mules through pristine pine-oak forest at higher elevations and tropical dry forest at lower elevations” (^{Duellman, 2015b:56}). His experiences in Mexico that summer had a profound impact on Bill, and began his fascination with the neotropics that continued throughout his long and adventurous life.

Bill made many other excursions to Mexico while a student at Michigan, including spending six weeks in Michoacán in 1955 and again in 1956. He earned three degrees from the university -a BA (1951) was in zoology with a minor in geography, MS (1952) in zoology with a minor in botany, and a PhD (1956) in zoology in with a minor in geology. Bill’s choices of academic minors are revealing and they are a reflection of his deep interest in biogeography. His doctoral dissertation was on snakes of the genus Leptodiera, many of which he had collected in Mexico (^{Duellman, 1958}). In his dissertation, he synonomized a species (Leptodiera duellmani) that had been named for him by a fellow Michigan graduate student, James A. Peters, an early indication of how important systematic was to Bill-he was far more interested in accuracy than he was in having a snake species named for him.

In 1953, while a graduate student, Bill married Ann Schiewetz (for whom he named Agalychnis annae in 1963) who accompanied him on many collecting trips. They had two daughters, and later divorced.

Bill’s first job after earning his PhD was as a biology instructor at Wayne State University in Detroit. While teaching there, Bill made three more trips to Mexico, including an assent of Volcán San Martín, explorations of southern Veracruz, Michoacán, Guerrero, and Oaxaca, and the northern slopes of Sierra de Juárez near Vista Hermosa in Oaxaca.

In the spring of 1959, Bill was hired as Assistant Curator in the Natural History Museum and Associate Professor in the Department of Zoology at the University of Kansas (KU). Although he was just 28 years old, Bill already had a major grant from the National Science Foundation, 37 publications (totaling 554 pages), and had spent 21 months doing field work in the US and Mexico. When he arrived at KU the herpetological collection consisted of a mere 59,000 specimens (most of the specimens collected by Bill’s predecessor, Edward H. Taylor, had gone to other institutions), so Bill quickly set about building the collection and recruiting graduate students to work with him.

In 1955, Bill’s major research focus had begun to shift from lizards and snakes to frogs, and at KU his interest in frogs intensified as his field work spread from Mexico into Central America, particularly in Guatemala, Costa Rica, and Panama. Bill continued to take students to Mexico and Central America for summer field work until 1966. As a result of the summer trips and the number of graduate students who came to work with Bill, all too soon the specimens they collected overflowed the small space that the museum allotted to the Division of Herpetology. When a new wing was added to the museum building in early 1963 Bill and his graduate students moved 8,000 jars containing nearly 90,000 specimens into a spacious new collections room, preparation laboratory, and sound laboratory.

In April of 1965, Bill married Linda Trueb, and the two became partners in research, teaching and managing herpetology at KU. Their daughter, Dana, was born in 1970.

While working in Central America, Bill had become interested in the use of sound recordings to distinguish frog species. Recording in the field in those days was not easy. Portable reelto-reel tape recorders were expensive, fragile, cumbersome to use, and the batteries had a short life. To make a good recording it was necessary to memorize the controls on the machine so you could operate it in the dark. Once you located the frog you wished to record, you had to turn off your headlamp and stand perfectly still, the heavy recorder hanging from one shoulder, while holding a microphone close to the frog. And then wait, and wait, and wait for it to sing again, while you were plagued by mosquitoes as your feet were sinking into the mud. If you were successful in making the recording, you then had to put away the microphone, turn your headlamp back on, find the frog you had just recorded, and catch it. Many of us who did fieldwork with Bill learned how to make field recordings but the only person I ever knew who enjoyed doing it was Bill (I was able to make good use of the recording techniques I learned from Bill later for a project with white-crowned sparrow songs while a graduate student at San Francisco State University). Back in the laboratory at KU, an audiospectographic analyzer was used to produce graphic images of the frequencies, pitch, duration, and pulse rate of the calls for analysis and publication (^{Duellman, 1968}). What made the KU collection of frog calls especially valuable was that, in most cases, the collection included both the tape recording and the particular frog that was recorded, so songs could be positively correlated with individuals. Bill’s lifetime collection of frog calls has now been digitized and the recordings are available through the Macaulay Library of Natural Sounds at Cornell University (https://www.macaulaylibrary.org/).

Bill spent more than ten years collecting and studying specimens for his two-volume work, Hylid Frogs of Middle America (^{Duellman, 1970}). I learned about this project when I was confronted with a formidable stack of 1,657 manuscript pages, a part of which I had agreed to help Bill proofread over a holiday weekend in 1970, in exchange for meals (I was a poor student at the time). Helping Bill proofread was a remarkable opportunity for a lowly undergraduate. I learned several things from that experience, including that proofreading was important but extraordinarily dull and tedious, that Bill had very high standards for accuracy, and that it took an enormous amount of scientific data to make a publication. Purchasing a copy of the book was beyond my meager means (it cost US $25, which was a lot of money at the time), but shortly after its publication, Bill surprised me one day in the lab with a gift. Handing me the two volumes, he quipped, “This is the Old Testament, and this is the New Testament. Learn it.” I have never forgotten the first line I read in the book’s introduction, which said: “When the first crossopterygian crawled out of the rich Devonian waters and cast the first envious vertebrate gaze at the terrestrial world, a boundless empire awaited colonization” (^{Duellman, 1970:1}). It says a lot about how Bill conceptualized the place of frogs in nature.

Many people have wondered why Bill switched his research focus to frogs after working for many years on lizards and snakes. I once asked him that question, and he replied by repeating an anecdote that is included his book: “During a visit to the Academy of Natural Sciences of Philadelphia many years ago, I handed the late Emmett R. Dunn two hylids that he had identified as different species and asked him how he distinguished one from the other. He carefully compared them for a minute and then boldly announced: ‘They look different. That’s how’” (^{Duellman, 1970:21}). This piqued Bill’s unquenchable herpetological curiosity and he set out to find reliable, useful characters to tell species apart, a task he often said was much more difficult than he expected, but ultimately successful.

Bill made his first trip to South America in November of 1966, to Ecuador to check out a potential site in the Amazon at a remote camp near the Cofán village of Santa Cecilia. Impressed by the diversity of the amphibians and reptiles he saw there, he applied for funding and began work in the area with colleagues and students the following year. In 1971, one of Bill’s graduate students, Martha (Marty) Crump, who already had field experience in Costa Rica and Brazil, decided to do her PhD research at Santa Cecilia. I had the good fortune to be her field assistant for a year. Bill joined us twice while we were there. On one extraordinary night in April 1972 the three of us found 56 species of frogs, a record for a single site in one night. The Santa Cecilia project resulted in the first comprehensive publication on a long-term study of an Amazonian herpetofauna (^{Duellman, 1978}).

As an undergraduate I took three courses from Bill- biogeography, herpetology (which was co-taught with Linda Trueb), and a special course that Bill taught just once for a group of five of us undergraduates. These courses revealed a lot about Bill’s approach to science. Both biogeography and herpetology began with a short history of the subjects and an introduction to the literature. Bill’s lectures demonstrated his astoundingly broad knowledge of geography, geology, botany, and zoology, his delight in talking about science, his extensive knowledge of the literature (which he emphasized by bringing rare publications to class for us to examine), and lots of his famous stories. Through these courses I learned why it was important to build a personal research library. Although there was a library in the Division of Herpetology, the personal library that Bill and Linda maintained at home was far more extensive, and they generously shared access to it with their students and colleagues. It was Bill and Linda who stimulated my life-long interest in the history of science.

During part of my undergraduate years, I rented an apartment from Bill and Linda in the basement of their house. The rent was very modest, and in return, I helped take care of their daughter, Dana. One interesting thing I learned from that experience was that there was no clutter in Bill’s life-his home office, like his museum office and laboratory bench, were always neat and organized, as were his files and his library, and as far as I could tell, his thoughts and ideas. He was an inveterate listmaker, so much so that we used to joke that he kept a list of his lists.

Bill had few interests outside of herpetology, other than watching professional football games on television and reading adventure-themed novels-he always brought along a stack of books to read along on field trips, and shared them with his companions. To say that field work was important to Bill is an understatement. He loved being in the field, looking for amphibians and reptiles, and he encouraged his students to do field work as well. As he wrote in a self-reflection in the final chapter of his masterwork on marsupial frogs, “Nothing substitutes for first-hand observation of the animals in their natural habitat” (^{Duellman, 2015a:399}). Bill was a generally upbeat, optimistic person, but he was never happier or more relaxed than he was in the field. I was fortunate to be able to spend thousands of hours in the field with him, including times when the work went exceedingly well, and times when things were just awful. But through it all, Bill’s enthusiasm rarely flagged. When he was at his happiest, he would begin to hum, and sometimes to sing, an old American folk song, “Sweet Betsy from Pike.” I regret never having asked him why he liked that particular tune, but every time I hear it I think of Bill, happily ambling down a forest trail, his headlamp gleaming in the night.

In May of 1974, Bill, Linda, daughter Dana (then four years old), and I set out for 14 months of field work in South America, a journey Bill described as his “Trip of Dreams” (^{Duellman, 2015b:123-136}). Our vehicle was a Ford 350 truck with a chassismounted camper (Fig. 2), designed for use as both living and laboratory space. In May of 1974 we left Kansas and drove to Panama, where we put the truck on a boat bound for Colombia. After an unexpected two-week delay, the truck finally arrived at the port in Baranquilla and we headed east across Colombia and Venezuela to Cumana, then south to the Brazilian border with Venezuela, and back across the llanos to Bogotá. From Bogotá we zig-zagged down the Andes, drove around Lake Titicaca, and into Bolivia, and then on south to Argentina, where we spent Christmas. We crossed the Andes into Port Montt, Chile on New Year’s Eve (Fig. 3), and worked our way back up the Andes to Buenaventura, Colombia. Throughout the trip, we did ecological studies of high-altitude Andean amphibian and reptile communities and made collections in areas that were of herpetological interest. As one might expect, we had many adventures (mostly good), many flat tires and a few mechanical problems, and we all managed to remain friends despite the tight quarters. By the time we returned to the United States in July of 1975, we had driven 55,793 km through 15 countries and collected 11,006 specimens.

Figure 2 Linda Trueb, Dana Duellman, William E. Duellman, and John E. Simmons, at the start of their year-long trip through the Americas, May 1974. 

Figure 3 Linda Trueb, William E. Duellman, Dana Duellman, and John E. Simmons in Puerto Montt, Chile, 31 December 1974. 

After I graduated from KU in 1976, I worked first at the Fort Worth Zoological Park in Texas, then at the California Academy of Sciences as collection manager for herpetology. In 1981, I returned to KU to become the herpetology collection manager in the Natural History Museum. The job of collection manager was a new position for the museum, and Bill gave me considerable freedom to determine what the job should entail in addition to the basic tasks of cataloging specimens, keeping the collection in order, and assisting visitors. Although at first a bit skeptical, Bill came to appreciate how useful it was to monitor the collection storage environment, test the quality of preserving fluids, develop a system to document collection care activities, and let me run the preparation laboratory. This was a very productive time in the Division of Herpetology. There were a lot of graduate students on hand, and Bill organized an international symposium which resulted in his 1979 book, The South American Herpetofauna: Its Origin, Evolution, and Dispersal (^{Duellman, 1979a}) and edited another major book, Patterns of Distribution of Amphibians. A Global Perspective (^{Duellman, 1999b}). In 1980, Bill and Linda began writing their landmark textbook, Biology of Amphibians, published in two editions (^{Duellman & Trueb, 1986}, ¹⁹⁹⁴) that summarized information from more than 2,500 references in twelve languages, as well as their own research. Their approach to the subject was summed up when they wrote that “Throughout the book we have stressed function and evolution” (^{Duellman & Trueb, 1986:XVI}). This broad approach was a hallmark of the herpetological laboratory at KU and the students it attracted.

The graduate students in the Division of Herpetology were a diverse group, particularly once Linda officially became both a Curator and Professor of Systematics and Ecology and could recruit her own students. At one point, the native Spanish speakers outnumbered the native English speakers in the herpetology division. During the 1980s the custom was started of having weekly meetings at noon each Monday when everyone got together to catch up on what each other was doing, and to listen to Bill tell stories about field work and his colleagues (Fig. 4).

Figure 4 William E. Duellman in the Natural History Museum at the University of Kansas, August 1980. 

Bill was generally easy to get along with and supportive of the graduate students, but like all of us, he could be difficult and intransigent at times. Bill usually had clear favorites among the students, which resulted in some individuals rightly feeling unappreciated and neglected. Sometimes his favorites were not the hardest working or most accomplished students, but the ones who would listen the longest to his endless stream of stories. Bill could be stubborn, and so focused on his own work that that he seemed oblivious to people’s personal problems, and on a few occasions included himself in other people’s projects. In general, however, Bill was careful to acknowledge people who helped him, and I know of several instances in which Bill quietly reached out to help students and colleagues in significant ways. Somewhat to my own amazement, Bill kept me employed throughout my prolonged undergraduate career despite my rather dismal academic performance. When I returned to KU in 1981, I took advantage of being a university employee and earned a Master’s degree in Historical Administration and Museum Studies, with Bill’s approval and support. Despite the fact that my job was technical rather than academic, Bill encouraged me to present papers at professional meetings and to publish, just as he encouraged his graduate students, and arranged for me to participate in many field excursions. Bill set high standards for himself, and he expected his students and employees to do the same.

In the 1990s Bill found another opportunity to conduct a comprehensive study of an Amazonian herpetological community at a site in Peru called Reserva Cusco Amazonico, a seasonal rainforest in southeastern Peru (Fig. 5). An ecotourist lodge, Cusco Amazonico was far more comfortable than the living quarters had been at Santa Cecilia a decade earlier (as was the food). Work there began in October 1983, and over time Bill invited several graduate students and colleages to participate in the project (I was a member of the 1986 crew). Ultimately, 151 species of amphibians and reptiles were recorded from the site, along with a wealth of data, which was summarized in another book, Cusco Amazónico, the Lives of Amphibians and Reptiles in an Amazonian Rainforest (^{Duellman, 2005}). During his work in Peru, Bill met a representative of Occidental Petroleum Company and invested a lot of energy in developing a project and doing exploratory fieldwork at the company’s concession in the northern part of Departamento de Loreto. The project was planned to be an example of how a petroleum company could support research and protection of biodiversity while exploring for and extracting oil, but unfortunately the company ceased their Peruvian operations before extensive fieldwork could get underway.

Figure 5 William E. Duellman preparing to photograph a Leptophis ahuetula at Amazonic Cusco, 30 November 1986. 

Bill’s single-minded focus on his herpetological pursuits sometimes led him to make unfortunate decisions that resulted in the failure to acquire the required permits and permissions for the specimens he collected. Bill had started doing fieldwork in a different era, when in most places around the world it was legal to collect amphibians and reptiles and take them back to the United States. Unfortunately, as laws and regulations changed, Bill had difficulty adjusting to the requirements for detailed research plans, permits, licenses, limits on collection size, and declarations of export and import, and he had no patience with officials who he believed did not understand the needs of fieldwork and research. During my time as collection manager at KU, I often had troubled convincing him to provide copies of the legal paperwork associated with his collecting trips for the files, even when I knew that he had all the documents that were required. Ultimately, Bill was penalized for two of his lapses, and in both instances had to publish letters to the herpetological community about what he had done in addition to paying fines (^{Duellman, 1979b}, ^1999a).

Bill retired as curator and professor in 1997. Free of onerous administrative duties, he took advantage of the extra time to work on his research with a flurry of significant publications.

In 2001, he produced a new edition of his famous Hylid Frogs of Middle America (^{Duellman, 2001}) that expanded the original text from 753 to 1,170 pages and added information on 50 new species and included 20 new full-color plates. For this new edition, the original plates were re-scanned for printing (Fig. 6). Bill had long been interested in marsupial frogs, going back to when his former mentor at Michigan, Charles F. Walker, “encouraged me to investigate their taxonomy and evolution” (^{Duellman, 2015a:XI}) which culminated with the publication of Marsupial Frogs. Gastrotheca and Allied Genera (2015a), which was awarded an Honorable Mention in the category of Single Volume Reference Books in Science by the Association of American Publishers in 2016. Some of the most interesting experiences I had with Bill in the field involved marsupial frogs, from hearing Gastrotheca calling at night as snow was falling in a marsh at more than 3,300 meters in Ecuador, to the thrill of seeing Stefania in the Guiana Highlands of Venezuela, to watching a female Gastrotheca use her hind feet to release newly metamorphosed larvae from the pouch on her back. For his book, Bill -ever the orderly maker of lists- reported that he had examined 4,661 preserved adult specimens, 191 lots of tadpoles, 264 young frogs, 95 dried skeletons, and 66 cleared and stained preparations from 78 collections on three continents.

Figure 6 William E. Duellman signing the 2001 edition of Hylid Frogs of Middle America at the SSAR meeting, 2001. 

By almost any measure, Bill led an extraordinary life. He traveled widely and collected specimens of almost every group of reptiles and amphibians (except sea snakes -Linda never let him forget that she once found a Hydrophis on a beach in Costa Rica). Bill described 252 currently recognized species, published 386 papers and books, and served as major professor for 34 PhD students. During his time at the University of Kansas Natural History Museum, he built up the collection from 59,000 to more than 300,000 specimens in just 35 years (^{Ford & Simmons, 1997}) through extensive field work by himself and his students and by acquiring other collections, making it the fourth largest herpetological collection in the United States, and with by far the most significant collection of the herpetofauna of Latin America.

The last species that Bill described he named Osteocephalus omega, for the ultimate letter of the Greek alphabet (^{Duellman, 2019}). But this was not his final contribution to herpetology. Bill kept working, despite increasing pain and declining health, until a few days before his death. When he died on 25 February 2022, he was trying to finish a major project with his former student, Luis Coloma -a comprehensive treatise on amphibians of Ecuador.

Although this obituary is based primarily on my own memories and experiences, I have also relied on ^{Burrowes et al. (2022)}. ^{Coloma and Guayasamin (2022)}, ^{Duellman (2021)}, ^{Mendelson (2022)}, and ^{Willhite (1998)} for additional information.