When El Jefe, as the big cat became known, crossed the border from Mexico and entered Arizona, he was only the fourth jaguar to be sighted in two decades in what was once prime territory for the animal.

What was even more remarkable was that he stuck around until at least 2015 despite reported encounters with hunters and their dogs, wildlife biologists and even possibly a few eager conservationists who kept silent about their sightings. The name, El Jefe (which means "Boss" in Spanish), evolved from a contest conducted with the help of students of a Tucson middle school from five proposed by the voting public.

Twenty-one million viewers in the U.S. saw a video of the jaguar produced by an Arizona conservation group. The final trail photo sighting of El Jefe was taken in the fall of 2015. Most authorities believe he headed back to Mexico in search of a mate.

These magnificent big cats once ranged from the western United States and down through Mexico and Central America to the tip of South America. Predation, encroachment on habitat and other factors continue to endanger the survival of the jaguar. As Campbell notes, "Currently, a quarter of all mammals, and an eighth of all birds, are classified as threatened with extinction."

Campbell's book is an engrossing story of adventure, science and the efforts of dedicated conservationists and individuals working against great odds to save the jaguar from extinction. The author was inspired by the work of individuals like the late Alan Rabinowitz, Howard Quigley and others, and those who follow in their footsteps, continuing the fight.

Campbell took personal risks, venturing from the deserts of the American Southwest and Mexico to the steaming swamps and jungles of South America, for an opportunity to glimpse a jaguar himself and to document the work of those striving to save the talismanic creature once feared and worshiped by indigenous peoples throughout the Americas.

It's a story well-told and worth telling.