One jaguar died and one survived a historic release into the jungle of Mexico's Yucatan Peninsula — an effort aided by an Arizona veterinarian and at least two Arizona biologists.

The dead jaguar, about 2 years old, was found in the jungle about nine days after her release in late May. Her body was so badly decomposed that officials said it was impossible to determine why she died.

The surviving jaguar, age 5 to 7, is still roaming under the dense canopies of the privately owned nature preserve where she was released. Pictures taken by cameras placed in the area show she is in very good condition — "fat and sassy," said Ole Alcumbrac, a Lakeside, Ariz., veterinarian who helped organize the jaguar release in cooperation with the Mexican government.

Carried out after two years of planning, this was the first release of jaguars from zoos that made use of a wide variety of techniques aimed at preparing the animals to survive in the wild, officials associated with the project said. It was probably one of the first jaguar releases from zoos anywhere.

Alcumbrac and other authorities who worked on the release proclaimed it a success, despite the death. They said the surviving cat's progress showed that jaguars held captive for some time still can survive in the wild. They also raised the possibility that released jaguars could provide breeding stock for areas where the cats have been eliminated.

But the death of the younger jaguar raised questions. Authorities who worked on the project said last week that in retrospect, they weren't sure if she had been ready for release because she was captured at a very young age. In future releases, they said, they are likely to give jaguars more time to get used to the wild before letting them loose.

The jaguars were released into the Calakmul Biosphere Preserve, a 1.8-million-acre area owned by the Nature Conservancy. The jungle is so dense there that it took workers for the project eight hours to hack with machetes about 1.3 miles into the area to hunt for the older jaguar's kill sites.

The effort was run by the Mexican government, but it worked closely with Americans who raised $30,000 to $40,000 for the project and flew to the area. Participants included two Texas Tech University wildlife experts and an official with a wildlife veterinary dental foundation from Colorado. The jaguars got repairs to canine teeth, including a root canal for the younger jaguar, after each animal broke a tooth trying to escape from its cage. After being trained to hunt for prey in the wild, the jaguars were released before Mexican television cameras because the government wanted to make the public aware of problems jaguars face and the importance of protecting them and their habitat.

"This is a way of helping animals get out of jail," Alcumbrac said. "We were able to extend our hands across borders to help wildlife, to establish a model to continue work to help a jaguar or any animal who runs into a human-animal conflict."

The young animal looked healthy when both jaguars were released into the jungle near springs. But it had been captured at an age, as young as six months, when many jaguars are still learning how to survive in the wild and had lived in captivity since then. It could have died from a snakebite or from the stress of its release, Alcumbrac said.

Since this kind of release hadn't been done before, "We didn't know for sure what would happen," said veterinarian Ivonne Cassaigne, who is head of the Mexican unit of Wildlife Health Services, a private, international group of veterinarians and biologists, and a former professor of wildlife conservation medicine. "Yes, the younger one was caught probably too young, but she was perfectly killing the live prey in her rehab process. She didn't like humans to approach her, so she wasn't imprinted, which would have put her forever in the zoo."

She probably was stressed because she hadn't lived enough in the wild to remember normal behavior for survival, Cassaigne said. But on the other hand, the older female had spent more time in captivity and authorities also had many questions about whether she would remember how to behave when back in the wild, she said.

"Predators being reintroduced face many things. Social predators are even more complex. But how could we know for sure what would happen with both of them?" Cassaigne asked.

Delaying the younger cat's releaseto give authorities more time to prepare her, Cassaigne said, could have meant she would never be released.

"Giving her a chance in the wild and learning for future releases definitely was better for the conservation of her species than having her just die in a cage," Cassaigne said.

Both jaguars met all the standards the project established for release of the animals into the wild.

They had passed blood tests. Their release site had plenty of active prey, ranging from monkeys to javelina to deer to birds. The release area was devoid of humans and livestock.

Finally, the animals were killing and eating prey within their enclosures before their release, including wild turkey and chickens, deer and javelina, said Alcumbrac, who is director of Wildlife Health Services.

Still, in the future, Mexican authorities are likely to try a "soft release" to give jaguars more time to adjust to the wild. They would be penned in a one-acre, caged area while awaiting their freedom. By feeding the animal there, it is thought that the jaguar might later have memories of being fed there and return to the caged area if it wants to.

The jaguar death "is not something we like because when we liberate them, we want them to survive," said Fernando Cortes Villavicencio, an official with the Mexican wildlife agency Semarnat, which coordinated the release. "But there are many examples of death of animals when releases are made, especially among carnivores. . . . Here in Mexico, we have a population of jaguars that allow us to do this kind of work and it is a much different situation than in Arizona."

Two environmental groups based in Tucson, the Center for Biological Diversity and the Sky Island Alliance, were far less critical of this effort than they have been of Arizona Game and Fish Department's capture last February of jaguar Macho B, who was euthanized 12 days after his original capture.

Sky Island's David Hodges said he saw "no obvious clues that they had screwed up." Michael Robinson of the center said a "soft release" probably should have been done, but he commends researchers for collaring the animals and trying to learn more about jaguar ecology.

A wildlife technician who played a key role in the Macho B case said she believes the Mexican government took too big a chance with these jaguars.

"The soft release would be the most appropriate way to introduce an animal to a new area. Wildlife rehabbers do it all the time," said Janay Brun, the Arivaca-based employee with the Borderlands Jaguar Detection Project who has accused her fellow detection project official Emil McCain of telling her to leave female jaguar scat at a trap site to lure Macho B — a charge McCain has denied. "The idea to give these animals another chance is fantastic. But it should be done with every benefit given to the animal in advance."

California veterinarian David Jessup, who criticized Macho B's capture, said the Mexican situation is clearly different, in that the government recognized the project's failings and plans softer releases in the future. Arizona Game and Fish has refused to say that it did anything wrong, Jessup said, although it has said it will review its jaguar capture protocols.

It would be asking a lot of the Mexican government to have anticipated that a hard release of the jaguars wouldn't work and to have planned a soft release, he said.

"Nobody has a lot of experience in hard versus soft release with jaguars," Jessup said. "People generally do what is easiest first — let 'em go and see what happens."

But Paula Ponte, a feline veterinarian from Boulder, Colo., who has taken an interest in the fate of jaguars, said the younger cat never stood a chance of surviving in the wild.

"They had no business releasing this cat under the conditions described. She was captured too young to have learned what she needed to know to survive, which includes things like who to be afraid of, what is suitable prey, what makes a secure den," Ponte said. "It was like sending a 10-year-old child out on the streets to survive on his own."

"This is a way of helping animals get out of jail."

Ole Alcumbrac,

who helped organize release

Contact reporter Tony Davis at 806-7746 or Follow Tony Davis on Twitter at tonydavis987