You're out walking through forest or along a beach. You find an injured bird. Maybe you find many, maybe thousands, like residents of the Kapiti Coast did recently when a southerly storm delivered a "prion wreck" to our shores. What should you do?

The prion-wreck last month was a natural event. Prion-wrecks occur every 10-30 years or so, although this was a big one. Most were broad-billed prions and New Zealand is home to more than a million of them. They are also common in Argentina, Australia, Falkland Islands, Peru, South Africa and many of the islands in between.

Emperor penguins, like Happy Feet who recently stole our hearts and "swallowed" our cash, are also remarkably common in the wild with an enormous range across Antarctica. These species are not rare, vulnerable or endangered. The International Union for the Conservation of Nature lists them as of 'least concern'.

Related story: Happy Feet's priceless publicity

Most of the prions were found dead. Some of the thousands alive were rescued only to die soon after. Hundreds were delivered to rescue centres. Many more died there. A minority will survive their rescue to be released.

Then what? How many will survive the release? Of those few that survive, how many will breed and so contribute to the future of their species? Probably just a few. Is the conservation outcome worth the investment? Conservation scientists don't think so. They are uninterested in the practice because its contribution to solving our world's conservation crisis is trivial.

When researchers from Deakin University asked 134 bird experts from Australia and New Zealand what they thought were the most pressing conservation priorities, bird rescue and rehabilitation did not even make the list of 29 priorities.

New Zealand has many bird rehabilitation centres - 34 are listed online. Those doing the work may not realise that they are doing far less good than they would like.

Just a few birds, if any, survive to breed. Rescue and rehabilitation can also do more harm than good because released birds that survive but never breed use the resources of those that might. Diseases carried by just a few into rehabilitation centres can spread to many others, especially among individuals already weakened by their ordeal.

Released birds may take the disease back into the wild to expose otherwise healthy birds in greater numbers.

Many centres also release non-native birds - competitors and killers of our native plants and animals - a most bizarre contradiction of the conservation ethic.

Wildlife rescues distract our attention from the real conservation issues: habitat loss, invading exotic species and pollution of our air, soils and waters.

Evidence suggests that not only are rehabilitation efforts wasteful and misplaced, the enormous resources invested would be better spent protecting and restoring habitat, and controlling introduced predators such as rats, possums and cats. Such actions are more likely to benefit New Zealand's native species in the long term. The $30,000 spent rehabilitating Happy Feet would support the restoration of a wetland or forest remnant, for example, providing habitat to many species, not just a single bird.

Rehabilitating prions or an emperor penguin is unlikely to change the future for either species. Even where a native bird warrants rehabilitation because it is extremely rare, such that the need for every individual is desperate, its release will not address the reasons for the species' perilous existence. Solving the world's extinction crisis will not come from rescuing and releasing individuals back into pest-infested and declining habitats. Successful pest control and habitat protection and restoration, on the other hand, reduces the need for costly and risky rehabilitation.

We need to be honest with ourselves. Bird rehabilitation can too easily become an exercise in self-promotion, not conservation. Generating a media profile carries many benefits for them and so they typically don't ask the tough questions, but we need to. We need to know how many rescued birds survive to breed after release so that we can know when the effort and cost is justified. Armed with this information, we can decide which injured birds to euthanise and which to rescue.

The Conservation Department publishes a guide to native bird rehabilitation to meet the demands of potentially thousands of people countrywide who devote well-meant hours and considerable collective resources to the rescue, recovery and release of birds.

What that guide does not do is give advice about which birds require rescue because they are very rare and those for which species rescue should not be attempted because it might do more harm than good or divert resources from more pressing priorities.

We need a smarter approach to wildlife rehabilitation guided by research and the conservation realities.

Unfortunately, rehabilitation success is rarely measured or reported. The outcome of bird rescue and rehabilitation, especially in terms of bird survival to breed in the wild, needs to be measured. If organisations continue to invest in this practice, then they need to also be investing in post-release monitoring so we can learn from the experience.

I predict few injured birds will warrant the costs of rehabilitation when their low chances of breeding after release are known.

When trying to prove me wrong, be prepared for monitoring of birds after release that will be costly, time- consuming, frequently fail and, therefore, seldom be useful. But persist because our rehabilitation efforts need to be informed by evidence of benefits.

The media coverage about Happy Feet's rescue and care deceives us into believing that wildlife rehabilitation is about conservation, but it is often not. Much bird rehabilitation is unjustified, might even be counter-productive, and not motivated by conservation.

Helping is not always best for the birds.

Next time, before you hand a bird over to a rehabilitation centre, make an informed judgment with the help of local veterinary and conservation expertise about whether the bird is worth rescuing or better humanely destroyed.

We mean well when we rescue a bird, but doing well requires informed decisions. Sometimes the right decision is to kill. In the interests of rescuing our planet, we need to think beyond the injured bird on the beach and instead lift our eyes and collective actions to the distant horizon.

Wayne Linklater is a senior lecturer at the Centre for Biodiversity and Restoration Ecology, Victoria University.