A survey of about 600 scientists published this week found that a majority think it's time to consider conservation triage - focusing resources on animals that can realistically be saved, and giving up on the rest.
Those that fall into the too-expensive-to-save category, it has been suggested, might include the panda and the tiger.
So, should we give up on one endangered species to save another? Here, two experts argue for and against triage.
FOR - Paul Goldstein, wildlife guide
I can't say which species we need to lose to save another. But if the only hope of survival for an animal - like the panda - is to be maintained in a holding facility or be born in a zoo, then I can understand the point of giving up on saving that species.
They cost too much to keep up and have little chance of ever living a natural life.
It's no good having a love affair with wildlife - that will not save endangered species. Anthropomorphic feelings, although understandable, don't always help. Animals don't have our emotions.
Many people would not back saving baby seals if they didn't look the way they did. People would not be as up in arms about that butchery if they looked ugly.
If people want to save every species then my question to them is - how?
If you want to save everything then you have to do it boldly and get to the root of the problem of creatures being endangered.
Tigers can be saved, but we have to get to the crux of the problem of why they are endangered. That goes for rhinos as well. The poaching of rhinos is the highest we've seen for many years.
People living near these species all have to benefit as well. It's no use if the benefit from funding endangered species goes to just a few people at the top - it has to be transparent, which it often is not.
Solving problems on a local level is a start but if the demand for body parts is still there, it is only postponing the problem.
Emotional provocations are not enough. You have to have pragmatism. That may not be sexy, but it's the only effective answer.
Is it fair for certain species that are not saveable in the long term to get the most money? I would say no.
AGAINST - Diane Walkington, WWF
The challenge that we face in trying to conserve our natural environment is huge, and our resources are finite. So it's easy to understand the frustration sometimes felt by scientists, as they watch the world's biodiversity decline at an alarming rate.
In the last 40 years, 1,700 species have declined by nearly a third. But that doesn't mean we should give up. As our founder Peter Scott once said: "We shall not save everything, but we shall save a great deal more than if we never tried."
It's an uphill struggle to protect the world's most endangered species and fragile habitats.
Earlier this month we confirmed that the Javan rhino has gone extinct in Vietnam. There is now only one population of around 50 animals left of this species.
If anything, this blow should make us redouble our efforts to save the last stronghold of a prehistoric species, which faces extinction purely due to the actions of mankind.
We have worked for half a century to save the tiger and it's true that numbers are dangerously low, however we firmly believe that the tiger has a future. Since the world tiger summit in Russia last year, we've already seen tiger numbers increase in India.
More importantly, the issue of triage isn't as clear cut as it may first appear.
Who will be charged with deciding which species should be saved above another? And what criteria will be used as the basis for that decision?
Ultimately you may end up with a model not dissimilar to that being used today, because conserving tigers and pandas equates to a push to preserve their habitats, and by extension all of the other species that share their home.
Over the years we've seen firsthand how wildlife, the environment and human activity are interlinked and it is clear that any effort to safeguard the natural world must be a package deal.