Alan Rabinowitz, a U.S. zoologist dubbed the “Indiana Jones of wildlife protection” by Time Magazine, died of cancer on Aug. 5 at the age of 64. He leaves behind a legacy of more than three decades of unceasing efforts to protect big cats and other wildlife at risk of extinction.

Rabinowitz was instrumental in the creation the world’s first jaguar sanctuary, the Cockscomb Basin Jaguar Preserve in Belize, as well the creation of protected areas in Thailand and Myanmar, and the discovery of new species.

In 2006, Rabinowitz co-founded Panthera, a nonprofit organization dedicated to the conservation the world’s 40 wild cat species and the vast landscapes that hold them, along with his close friend Thomas S. Kaplan, a U.S. entrepreneur and philanthropist.

The wildlife conservation community has lost a leader in big cat conservation.

Alan Rabinowitz, an American zoologist dubbed the “Indiana Jones of wildlife protection” by Time magazine, died of cancer on Aug. 5 at the age of 64. He leaves behind a legacy of more than three decades of unceasing efforts to protect big cats and other wildlife under threat of extinction. He is survived by his wife, Salisa, and their children, Alexander and Alana.

Rabinowitz achieved numerous milestones during his career. He convinced the government of Belize to create the world’s first jaguar sanctuary, the Cockscomb Basin Jaguar Preserve. He was instrumental in generating the first field research on Indochinese tigers, Asiatic leopards, and leopard cats in Thailand. He is also credited with discovering four new mammal species in Myanmar, including the leaf deer or Putao muntjac (Muntiacus putaoensis), which he came across while doing field research in a remote part of the country. His work in Myanmar also led to the creation of five protected areas, including the Hukaung Valley Tiger Reserve. It was while establishing this reserve in 2001 that Rabinowitz was diagnosed with chronic lymphatic leukemia.

In 2006, Rabinowitz co-founded Panthera, a nonprofit organization dedicated to the conservation of the world’s 40 wild cat species and the vast landscapes that hold them, along with his close friend Thomas S. Kaplan, a U.S. entrepreneur and philanthropist. Panthera has created conservation programs for cheetahs, jaguars, leopards, lions, pumas, snow leopards and tigers.

“The conservation community has lost a legend,” Panthera CEO and president Frédéric Launay said in a statement. “Alan was a fearless and outspoken champion for the conservation of our planet’s iconic wild cats and wild places. Inspiring a generation of young scientists, the boldness and passion with which Alan approached conservation was captivating and contagious. While we are devastated by his passing, we are comforted by the fact that his extraordinary legacy of advocacy for the most vulnerable creatures will live on in his legion of students and followers.”

In a tribute, Panthera co-founder Kaplan wrote that losing Rabinowitz was like losing a twin. “It is beyond mourning,” he wrote. “It is a loneliness framed only by the gratitude that our souls were granted an opportunity to meet and share a very special kind of joy — whether we were together, or apart.”

Rabinowitz’s love for animals began when he was a young child. Having suffered from a debilitating stutter while growing up, he vowed to become an advocate and a voice for animals if he ever overcame his stutter.

“There are two things that stutterers can do without stuttering: one is sing, and I could never sing. The other is speak to animals,” Rabinowitz told U.S. comedian and TV host Stephen Colbert in an interview. “So coming home from school … I would go into my closet and talk to animals like the chameleon, the green turtle, the gerbil, and I realized that animals don’t have a voice. They’re just like me. They can think, they have feelings, but they don’t have voices. So at a particular point in my childhood as they were allowing me to pour my heart out to them, I made a promise to animals. I swore to them that if I ever found my voice and stopped stuttering, or if I could control my stuttering, I would be their voice. I would actually try to speak for them and save them.”

Read Panthera’s tribute to Alan Rabinowitz here.