"Until his death, when we began to go over his work, I hadn’t fully appreciated his commitment to conservation," Ginette Hemley, vice president for species conservation at the World Wildlife Fund (WWF), told Discovery News.

"Steve Irwin put his money where his mouth was at, and he often did this quietly and effectively with little or no promotion."

She explained that Irwin partnered with the WWF to fund endangered species conservation in Africa and Asia, where he provided "critical support" in Manas National Park, India. That funding was used, in part, to buy field equipment for workers patrolling the forests there against poachers.

Irwin took a special interest in saving tigers, since they remain one of the world’s most endangered species.

In Africa, he also assisted the WWF with funding for projects to save cheetahs and other wildlife.

"His efforts got money to the ground level where it was most needed," Hemley said.

Irwin and his wife used money from their Crocodile Hunter earnings to buy wilderness lands in Fiji, Tasmania, the South Pacific island nation of Vanuatu and the United States.

In particular, Irwin was devoted to purchasing, and then salvaging, wilderness tracts in his homeland of Australia. There he bought a large region west of Brisbane near the Murray-Darling Basin.

He also purchased land near his Australia Zoo in Beerwah to save the habitats of tree-dwelling marsupials known as gliders, as well as wallabies, snakes, platypuses and other creatures, many native to Australia.

The Queensland Parks and Wildlife Service said Irwin expressed an interest in helping its population recovery efforts for the northern hairy-nosed wombat.

Irwin also took on smaller projects, such as working with farmers to save an endangered species of python called the woma. His zoo actually paid farmers to report information about the snakes rather than kill them, as was once widely done.

Irwin described himself as "a man in a hurry" who wanted to accomplish as much as he could in his lifetime to save wildlife and support environmental causes.

During a 2003 interview with The Age in Australia, he said, "I consider myself a wildlife warrior. My mission is to save the world’s endangered species."

Although his life was cut short by Monday’s tragic accident, Irwin’s work will continue, according to an announcement today by Michael Hornby, executive director of the Australia Zoo.

"We have an obligation now to do more, and through his legacy we hope more Australians and more people around the world will get into conservation," Hornby said on Australia’s Channel 9 Today program.

He added, "Things like the culling of wildlife, which Steve was very passionate (against). That has to stop. We’ve got to create safer habitats. We’ve got to carry on the mantle."