Jim Fowler, who with the zoologist Marlin Perkins introduced generations of television viewers to wild animals filmed in their natural habitats on the long-running documentary series “Wild Kingdom,” died on Wednesday at his home in the village of Rowayton in Norwalk, Conn. He was 89.

His son, J. Mark Fowler, said the cause was complications of heart ailments.

Mr. Fowler was a key part of “Wild Kingdom” (also known as “Mutual of Omaha’s Wild Kingdom”), which had its premiere on NBC in January 1963, when seeing elephants, cougars and other exotic beasts on television was still a novelty.

Mutual of Omaha, the insurance company, had advertised on a previous show featuring Mr. Perkins called “Zoo Parade,” and it agreed to underwrite a new show that ventured into the wild. Mr. Fowler, a naturalist, had been working with birds of prey, and Mr. Perkins had seen him on the “Today” show exhibiting an imposing harpy eagle, a bird native to the Central and South American rain forests. He invited Mr. Fowler to join him on “Wild Kingdom.”

Mr. Perkins, 25 years older than Mr. Fowler, was the host, and Mr. Fowler was his sidekick, often doing the bulk of the work — or so it seemed to viewers of early single-camera episodes. But that had actually not been the case, Mr. Fowler said in a 2015 interview with Connecticut Magazine.