Time is running out to craft a plan to save Earth's rich diversity of mammals, a quarter of whose species could be wiped out, biologists warned on Tuesday.
"A global mammal strategy is urgent," they said in a journal published by the Royal Society, Britain's academy of sciences.
Millions of people have rallied to the cause of large iconic mammals such as the tiger, the polar bear and the giant panda, they noted.
But the news for less visible species is grim, especially those with a commercial value for poachers or whose habitat is at risk from farming, development or impending climate change.
Of the 5,339 documented species of mammals that are alive today, a quarter are threatened with extinction in the wild, according to their estimates, appearing in the journal Philosophical Transactions.
"As of today, there is not yet a comprehensive, widely agreed, global conservation strategy to tackle the mammal decline," said Carlo Rondinini and Luigi Boitani of the Global Mammal Assessment Programme at Rome's Sapienza University, and Ana Rodrigues of the Centre of Evolutive and Functional Ecology in Montpellier, France.
They suggested the UN's Biodiversity Convention weave a single vision, identifying which areas and species are at risk and how resources can be mustered to save them.
This work should then be coordinated by an authoritative institution with global reach, such as the International Union for Conservation of Nature (IUCN).
Accompanying papers in the journal predicted that the biggest losses of mammal habitat will be in Africa and the Americas, while many species will be lost on the Mediterranean rim if predictions of climate change prove correct.
Quantifying such perils is hard, given that many mammals are elusive species and may live in fragmented, out-of-the-way habitats, the experts admitted.
Indeed, Australian investigators reported last September that of 187 mammals that have been "missing" since 1500, 67 species have subsequently been found again.
In one of the new papers, scientists reported on the world's biggest "camera trap" survey, aimed at getting an accurate idea of mammal populations, the size of animals and availability of food.
Creatures snapped automatically as they passed by a hidden lens ranged from a tiny mouse to the African elephant, gorillas, cougars and giant anteaters, as well as occasional poachers and tourists, according to the team from the US organisation Conservation International.
The probe set up 420 cameras at protected sites in Brazil, Costa Rica, Indonesia, Laos, Suriname, Tanzania and Uganda in a project that ran from 2008-2010 and yielded 52,000 images.
"We take away two key findings," said Jorge Ahumada of the NGO's Tropical Ecology Assessment and Monitoring Network.
"First, protected areas matter: the bigger the forest they live in, the higher the number and diversity of species, body sizes and diet types.
"Second, some mammals seem more vulnerable to habitat loss than others: insect-eating mammals - like anteaters, armadillos and some primates - are the first to disappear, while other groups, like herbivores, seem to be less sensitive."