Maybe it’s a baby robin that falls out of a nest in the backyard, or perhaps twin deer fawns left orphaned after their mother gets struck by a car or eaten by wolves, or perchance a bald eagle, behaving strangely, staggering on the ground and unable to fly.

When wild animals appear to be in distress, should human beings intervene to rescue them or is it better to back off and let nature take its course?

This existential question is being debated again following a recent incident in Yellowstone National Park involving a bison that raised eyebrows and attracted international media attention.

Earlier in May, a Canadian tourist captured a wild bison calf with his bare hands and loaded it into his SUV. The man, Shamash Kassam, said he found the animal alone and shivering along the roadside in Yellowstone’s wildlife-rich Lamar Valley. Once he turned it over to rangers, park biologists made several attempts to reunite the youngster with its herd but when the calf was rejected, they euthanized it.

Kassam was fined $110 for violating park regulations, which strictly forbid contact with wildlife, and is supposed to make a court appearance in June. Meanwhile, the incident ignited emotional exchanges on social media ranging from condemnation of the tourist to claims Yellowstone officials responded heartlessly.

Should the bison have been sent to a rehabilitation facility or turned back in its natural environment where it faced a high probability of falling prey to predators or dying from starvation?

Yellowstone, which has the most abundant and diverse array of large wild mammals in the Lower 48, has wrestled with the dilemma for decades as part of its “natural regulation” policy. The approach is designed to keep human interference to a minimum and it’s a philosophy generally upheld by most state and federal wildlife agencies across the country.

“The rule of thumb is that if human activity causes an animal to become injured or orphaned, we may intervene. If not—if it’s something that happened naturally—then we don’t,” says ecologist Doug Smith, who oversees Yellowstone’s wolf and avian management.

“Of course, as with everything, there can be exceptions and extenuating circumstances. Intervention requires justification,” Smith adds. (Read more about problems in Yellowstone.)

The Circle of Life

According to Jeff Olson, a spokesperson for the National Park Service in Washington, D.C., species considered common are less likely to be candidates for intervention. Further complicating the case, Kassam appears to have allegedly violated the code of federal regulations governing wildlife in national parks and forests, which prohibits “the feeding, touching, teasing, frightening or intentional disturbing of wildlife nesting, breeding or other activities.”

Marc Bekoff, professor emeritus at the University of Colorado-Boulder and a person in the vanguard of what’s called “compassionate conservation,” has been both a wildlife researcher and a leading voice in animal rights. Bekoff adheres to the nuanced view of Smith.

If wildlife officials attempted to save every animal in peril, it would be chaos, Bekoff says, and it would disrupt the function of natural ecosystems. Predators only exist by preying on other species—often the weak and the vulnerable—and a large array of scavengers also feed on carrion.

“Animals need to be free to be who they are," says Bekoff. "Death begets life in nature. I am sorry if you are born a prey species but that’s the way it is.”

View Images This bison calf was euthanized earlier this month after it was placed in a car by a visitor to Yellowstone.

The tourist in Yellowstone claimed the bison calf had been abandoned and would have become roadkill. But to the untrained eye, looks can be deceiving. In New Hampshire, the state fish and game department offers this warning to aspiring do-gooders: “Seeing a fawn (or a moose calf) alone does not mean it has been abandoned. It is normal for a doe to leave her fawn alone for several hours at a time while she is off feeding. She may not return until nightfall to nurse her fawn. This actually helps keep the fawn safe from predators.” (Read about the plight of New Hampshire's moose.)

Different states have varying protocols on whether to attempt rehab for injured animals or move immediately to euthanize.

The Minnesota Department of Natural Resources has an official motto for dealing with sick, injured or orphaned animals: “If you care, leave it there.” The department offers this perspective on its official webpage, which goes into detail for how to deal with different wildlife species, especially young animals, that may lead people to believe they are abandoned or could be helped with veterinary treatment: “The circle of life can be difficult to observe at times, but no animal goes to waste. Many species of wildlife rely on sick or injured animals to feed themselves and their young.”

If the person refuses to follow that guideline, the state advises contacting a local licensed rehabilitation center. It is strictly prohibited for a private citizen in Minnesota to rehab an injured wild animal on one’s own.

The Rescuers

One such licensed facility is the Montana Raptor Conservation Center in Bozeman, the largest of its kind in the state, with a service area spanning hundreds of miles.

“We approach each case on an individual basis,” says Becky Kean, director of the facility. “Our success rate, depending on the year, is between 35 and 40 percent.”

After sick or injured birds are brought in, they’re given an honest assessment, gauging the likely prospects for recovery. A lot of rehab centers have consulting veterinarians but few can do complicated surgeries, such as fixing broken wings.

For young birds lacking flight and survival skills taught by their parents, hard calls have to be made.

“If it’s at all possible to get them back up to the nest, that’s what we try to do," Kean says. "Sometimes we’ll even make an artificial nest to keep them out of harm’s way.”

Watch: See how a team photographed Yellowstone, one of the world's most beautiful places.

It’s not uncommon for raptors in Yellowstone, when they are stalking winged or mammal prey near roadsides, to become so locked in on their targets that they inadvertently crash into passing cars during their swift descents.

Last week, a peregrine falcon struck a vehicle and broke its wing. The bird, because it was injured by a human cause, was brought to Kean’s facility. Another patient was a bald eagle from eastern Montana that suffered a gunshot wound to the wrist and earlier another bald eagled received treatment for lead poisoning, caused by eating game birds filled with lead from shotgun shells.

In 2015, the conservation center cared for a record 234 raptors and over the years has treated almost 3,300. That’s thousands of birds of prey returned to the wild, not only fulfilling their ecological function but breeding to produce new generations. Without rehab, a huge percentage wouldn’t have survived.

It’s not always clear-cut. Back in the 1990s, a strong windstorm blew bald eaglets out of their nest in Yellowstone. Park officials said that because it was a natural event, they were left on the ground to cope with whatever fate would come.

On the other hand, Yellowstone netted a wolf along the roadside that was bloody and injured. Smith said it looked like it might have been struck by a vehicle. The lobo died shortly after being brought in for veterinary treatment but a necropsy revealed its wounds came from a fight with other wolves.

Every year, animals in Yellowstone break through thin ice on rivers and lakes. In streams roaring with snowmelt, young bison and elk, unable to navigate the current, are swept away. Some make it to shore and others do not. There is some speculation that the bison calf brought to Yellowstone rangers had become traumatized and separated from its herd because of a harrowing river crossing.

Public Pressure

Smith recalls the day a bison calf fell into Blacktail Pond. Human onlookers pleaded to a seasonal ranger to intervene as it slowly drowned. The ranger rescued the animal even though it went against park protocol.

“There was a lot of discussion after the fact," Smith says. "The consensus was the ranger did the right thing. Standing there doing nothing would’ve hurt our credibility. Nobody’s perfect. There are inconsistencies.”

Bekoff remembers watching a documentary on Yellowstone wolves made by filmmaker Robert Landis. A woman sitting in front of him expressed indignation that one of the scenes featured a bison that had become trapped in ice and slowly dying from hypothermia before it was feasted upon by lobos.

Landis has watched several bison die that way and intervention was never a consideration.

“For me, if you’re doing a film on wolves, getting a good predation sequence is a requirement because it’s an essential part of the life-cycle you’re trying to convey,” he says.

Landis’ film “Wolf Pack” won an Emmy for best science film. He has a two-hour film coming up on the Hayden and Canyon packs, which he’s followed for 10 years. The alpha pair of the Hayden Pack got killed by members of the Mollie Pack.

“Everyone wants a happy story, but if you are a predator, another animal must lose its life in order for you to live,” Landis says. “In nature there are no easy deaths out there, not for predators or for prey.”

Sometimes tinkering with the system and bending hard and fast rules is necessary to perpetuate a species. Smith invokes Yellowstone’s trumpeter swan population, which has declined from 17 breeding pairs to just two. At remote Grebe Lake, where climate change has caused more flooding of nest sites and rising numbers of hikers and anglers has caused disturbance, Yellowstone installed an artificial nesting platform and it yielded the first successful crop of cygnets since 1952.

Watch: See Yellowstone's "bear bathtub."

“Climate change is negatively impacting a lot of different species and it’s altering the rules of the game everywhere,” Smith says. “Is it natural or human-caused? If you conclude it’s the latter, you could argue for intervention with almost everything. With trumpeter swans, I don’t want to see the park population go down the drain on my watch.”

Of course, one of the most contentious episodes in Yellowstone history occurred last summer when a grizzly with two cubs mauled and partially consumed a hiker near the western shore of Yellowstone Lake. The mother bear was captured and ordered destroyed by park superintendent Dan Wenk out of concerns the grizzly could attack again.

What to do with the surviving orphaned cubs generated hundreds of thousands of comments, including a petition drive that called upon Wenk to send the bruins to a rehabilitation center and then re-release them in the wild. Wenk rejected that option and also opted not to euthanize them. Instead, he sent them to the Toledo Zoo in Ohio.

Bekoff had argued that the mother bear shouldn’t have been lethally removed. He also believed the cubs should have—for their own dignity—been let go in Yellowstone to try and make it on their own rather than spending the rest of their lives in a zoo. He doesn’t like zoos, he says, because they don’t allow predators to take down prey, because audiences don’t have the appetite for it.

“This can be hard stuff,” Wenk told me last year. “You’re not only making decisions about the life or death of animals but with social media sometimes the whole world is watching. No matter what you do, people will say you were wrong.”