Spending on conservation projects must rise by "an order of magnitude" if governments are to meet their pledges to manage protected areas and halt the rate of extinction caused by human activity.
A stark assessment from an international collaboration of conservation groups and universities reveals the enormous shortfall in funds required to save species, and warns that costs are likely to increase, the longer action is delayed.
To reduce the risk of extinction for threatened species, it would cost up to £2.97 billion every year, with a further £47.4 billion required annually to establish and manage protected areas known to be at risk from habitat loss and hunting .
Though governments agreed in 2010 through the Convention on Biological Diversity to reduce the rate of human-induced extinctions and to improve protected areas by 2020, progress has been limited.
"These seem enormous figures to us as individuals, but in terms of government budgets they are trivial," said Stuart Butchart, the global research co-ordinator at BirdLife International in Cambridge.
"The $3-5 billion to improve the status of threatened species and prevent extinctions is less than the amount that the Royal Navy's new aircraft carrier is over budget".
The costs will feed into the meeting of the CBD under way in Hyderabad, India. The costs to save individual species vary as widely as the strategies required. The ground-nesting raso lark is found on only one of the Cape Verde islands, and conservationists hope to reintroduce it to a neighbouring island. Before that, a population of cats introduced by humans must be exterminated. "They would probably wipe out any birds that you put there," said Butchart.
Efforts to protect rhino populations have focused on controlling poaching, guarding their habitats and providing suitable grasslands.
In the Mediterranean, a programme of captive breeding and reintroduction has improved the lot of the Mallorcan midwife toad.
For their analysis, the authors gathered details on the conservation of 211 globally threatened bird species and the costs to improve their status by one category on the red list of threatened species.
For example, a species ranked as endangered might be reclassified as merely vulnerable after a successful conservation project. The researchers devised a model that then extrapolated the costs of conservation to all threatened bird species.
Drawing on other conservation data for threatened mammals, amphibians, reptiles, invertebrates and plants, the scientists arrived at a model that could predict the costs for all threatened species.
In parallel, the team gathered information on the costs of protected areas for bird life and from these worked out how the cost would rise to establish and maintain safe havens for all threatened species.