A pioneer in the application of psychological science to the protection of wildlife and its environs, APS Fellow Carl R. Gustavson, was struck down at age 49 by a sudden heart attack on July 30, 1996. Gustavson dedicated his life and career to advocating a broad paradigm of psychology emphasizing analysis at all levels of organization, from the molecular to the ecological and the evolutionary. He strongly advocated for psychology to truly be the science of behavior complete with a rigorous dedication to empiricism and sound scientific thinking.
Carl Gustavson was born and reared in Utah where the tradition of the heroic hunter still echoes among the canyons, mountains, and deserts. But Carl grew to cherish the magnificent indigenous predators and sought benign psychological means to halt their demise and ensure their place in the ecosystem. In 1974, he began working on a method to prevent coyote predation on sheep that preserved both species. He calculated the most effective way to change a coyote’s predatory behavior was to take advantage of the coyote’s innate defense mechanism against poisoning. By pairing the flavor of mutton with nausea induced by mild toxins, Gustavson was able to convert sheep into artificially toxic prey. This began his fascination with feeding behavior- in its appropriate complex evolutionary and ecological context- and conditioned taste aversion (CTA).
CTA can be established even when many hours intervene between feeding and the onset of nausea. In contrast, the traditional method for establishing conditioned avoidance is to punish motor approach responses with immediate pain. This method merely causes animals to change their approach tactics to their still-tempting prey. Carl’s successful breakthrough was begrudged by behaviorists working in animal damage control, as they were puzzled by the prolonged temporal parameters of CT A and were chagrined by the neat solution offered by a novice and outsider.
Joan Carlson Gustavson, an APS Charter Member, was Carl’s wife and research partner. Their romance began in high school. They dropped out of high school in 1963, got married, went to work, attended night school, and, scarcely missing a beat, entered the University of Utah. Joan interrupted her education to care for their two sons, Andrew and Eric, who became active junior partners in the family research and thereby gained a first-hand education in ecology and psychology.
The first Gustavson tests of CT A on predatory choice were conducted in outdoor arenas and zoos with captive coyotes, wolves, and a cougar. They were spectacular. After consumption of prey flesh followed by nausea-inducing lithium treatment, coyotes and wolves turned away from live lambs and sheep. The cougar refused to ingest deer flesh but continued to eat cow and horse meat. Coyotes treated for eating rabbit flesh, their more familiar prey, refused to attack rabbits after a mere sniff or two. These observations counter the neophobic and non-associative explanations offered by some researchers working with laboratory rats.
Other scientists were inspired by Gustavson’s innovative work. These colleagues expanded the research with studies on various captive animals and found some species-related peculiarities. For example, Linda Brett showed that hawks treated with CTA would reject mice on the basis of coat color, if, and only if, the colored mouse used in training also tasted different. This work demonstrated that the typically flavor-specific CTA could include visual stimuli in a species evolved to rely on sight in its hunting.
Ken Rusiniak showed that, unlike the wild-bred canine, the laboratory-bred ferret would continue to kill but not eat its prey after CTA.
Deb Forthman demonstrated the feasibility of using CTA to prevent baboons from raiding vegetable gardens in Africa. In the 1980s, a high school student, Todd Hoffman, guided by his biology teacher, Lowell Nicolaus, won the international science fair prize with dramatic movies of raccoons scurrying away from chickens following their CT A training. As word spread, a plethora of comparative studies ensued, demonstrating CTA in all manner of vertebrates inhabiting terrestrial, acquatic, and aerial niches, as well as many invertebrates such as mullusks, arthropods, and crustaceans.
For field studies on the sheep ranges, Carl and Dan Kelly devised an inciting packet of mutton taken from dead and aged sheep, wrapped in sheep hide and laced with lithium salts. (Lithium salts are commonly found in earth and water and relatively harmless to the ecosystem.) To establish CTA in free-ranging wild coyotes, they scattered this bait over a sheep ranch in Washington and significantly reduced the lamb kills. Working with J.R. Jowsey, predator specialist for the Department of Agriculture in Saskatchewan, Canada, Carl validated the effectiveness of his lithium baits over much wider dispersion, leading to the adoption of conditioned taste aversion as the preferred Provincial predator control method. Stuart Ellins and his students, using a thorough program of spreading baits and injecting sheep carcasses with lithium, reduced sheep kills to zero in Southern California’s Antelope Valley. The very success of lithium baiting irritated those with vested interests in killing coyotes, such as pilots taking hunters up to gun down coyotes from airplanes and trappers killing coyotes for fees and pelts.
The impact of CT A met with an ambivalence in academic psychology as well. While neurobiological editors accepted CT A manuscripts with alacrity, the staid experimental journals took a jaundiced view of CTA papers. Nevertheless, the importance of CTA could not be denied, and a sizable literature accumulated in the establishment journals under rather arcane heading such as “Instrumental Responding for Devaluated Reinforcers.”
Similar antipathies were exacerbated among psychology department heads and committee members at the Gustavsons defended their viewpoint with logic and more concern for scientific truth and personal integrity than political expediency. They went wherever their work with this wide variety of species required. Carl had positions at Eastern Washington State University, North Dakota State University, the University of Texas Medical Branch-Galveston, and Arizona State University in Tempe. Along the way they broadened their ecological goals, published regularly, and gained many loyal adherents with their open collegiality.
Carl worked with Nicolaus to protect sandhill crane eggs from ravens and crows by injecting nauseous toxins into turkey eggs and coloring them to look like crane eggs. One advantage to their inventive approach is that the avian predators treated with CTA maintain dominion over their territory and fend off unconditioned conspecifics. This illustrates a general ecological principle. To wit, total eradication of a species deemed a pest, be it coyote, bird, or insect, is not always a good idea, as eradication may trigger an unforeseen chain of ecological disasters by also eliminating predators who depend on the pest, and by opening a wider niche for competitors of the original pest.
The Gustavsons’ contributions were not limited to the investigation of wildlife. Carl and Joan suspected that anorexia nervosa in adolescent girls might be an endogenous CTA triggered by endocrine reactions. They found estrogen injections can induce CTA in rats. They further developed their model into a comprehensive theory of human eating disorders, considering the interaction of biological, ecological, and evolutionary factors related to the etiology of these psychiatric diseases. Carl presented this theory and data at his address for the New Fellows symposium for Division 6, at the 1990 American Psychological Association meeting. In a similar vein, the Gustavsons developed a novel test of body image distortion and dissatisfaction, and conducted several normative, c1inical, and cultural studies using their assessment instrument. Working from the methodology developed by the Gustavsons, colleague Ann Rice, at the Univ. of California-Los Angeles, demonstrated that histamine blockers will ameliorate estrogen-induced CTA in rats. The Gustavsons also focused on human-animal dilemmas occurring with pets and with animals on public lands. Clear-cutting forests for grazing and riparian damage caused by unrestrained herds destroy habitats and foul the waters, making our land unfit for recreational and esthetic needs. Carl was affiliated with Arizona State University Center for Environmental Studies until 1995. In 1996 he established a private company, Biobehavioral Technologies, Inc. Carl was also doing statistical consulting for Arizona Game and Fish and Hubbs-SeaWorld. He was in the process of setting up the Garcia-Gustavson Institute for Wildlife Psychology.
His work still unfinished, Carl died as he lived. As ecological guardian of a vast wilderness, he was optimistic about new challenges in the offing. He expired in the care of his loving wife and devoted sons. His last words expressed his deep concern, not for his own agony, but for the distress his agony was causing those he loved.