Science 10 October 2008:
Vol. 322. no. 5899, pp. 178 - 179
DOI: 10.1126/science.322.5899.178b
 
News of the Week
ECOLOGY:
Comprehensive Conservation Database Details Threats to Mammals
Elizabeth Pennisi

For years, biologists and conservationists have expressed alarm at the plight of marine mammals and many large land mammals. But there's been no comprehensive look at how the world's mammals are faring--until now. Earlier this week, at its quadrennial congress, in Barcelona, Spain, the International Union for Conservation of Nature (IUCN) released its long-awaited database detailing the status of all mammals known to humankind since the year 1500. On page 225 of this issue of Science, the team that assembled the database analyzes the findings. The news is bleak, particularly for the oceangoers.
Overall, the analysis estimates that at least one-quarter of the world's 5487 known mammalian species are threatened with extinction--but an estimated 36% of the marine mammals are at risk. Although all mammals face habitat loss and hunting pressures, for marine species, accidental death--being struck by ships or caught in fishing gear--poses the most widespread threat, IUCN reports.

Mammals at risk. Locally extinct in some places, harp seals face future threats from melting sea ice.

CREDIT: PHOTOS.COM

The database, part of the IUCN Red List of Threatened Species, updates and expands a 1996 survey. The effort took 5 years and involved more than 1700 researchers from 130 countries. They combed the literature and pooled their unpublished knowledge of ecology, taxonomy, distribution, population trends, threats, and conservation efforts. The species were then classified according to their extinction risk. This new database has expanded coverage of marine mammals and of other groups, such as rodents, not generally thought of as being in dire straits. "We wanted to make this one-stop shopping for scientists and policymakers," says IUCN and Conservation International mammalogist Jan Schipper, who coordinated the project.
The good news is that well-funded conservation programs are succeeding. One example cited by Schipper is the recovery of the black-footed ferret in the United States, where it had disappeared from the wild and has been reintroduced from captive breeding programs (Science, 12 May 2000, p. 985).
Also encouraging is the diversity of mammals, which is richer than previously thought. Taxonomists have described 349 newly discovered mammals since 1992, including an elephant shrew from Tanzania early this year. All told, there were 700 mammals in this survey that were not covered in 1996.
The bad news is that 188 species are critically endangered, and 29 of them, such as a freshwater dolphin from China called a baiji (Science, 22 December 2006, p. 1860), may already be extinct. Since 1996, the risk categories and mammal classification schemes have changed, making it difficult to directly compare 1996 data with the new information, says Schipper.
Large land mammals, particularly hoofed animals and primates in South and Southeast Asia, are the worst off, Schipper's team reports. Marine mammals are most at risk in the North Pacific, the North Atlantic, and Southeast Asia.
All told, extinction looms large for 1139 out of the 4651 species for which there are good data. The other 836 species were so poorly studied that it was impossible to tell what their conservation needs might be. About half the species are declining in numbers, including one in five of those not at risk of extinction right now.
The new database "is the most valuable effort to date to summarize the state of conservation and threats to the world's mammal populations," says mammalogist Don Wilson of the Smithsonian National Museum of Natural History in Washington, D.C. "By detailing threats at the species level, it will now be possible for management agencies in every country in the world to prioritize their efforts to try to mitigate these threats."
There will likely be a payoff for basic research too, says mammalogist Gerardo Ceballos of the National Autonomous University of Mexico, who in 2005 compiled a similar database encompassing about 4500 mammals. These databases can reveal large-scale patterns of species distributions, Ceballos says, and their relationship to climate change and extinctions.

The editors suggest the following Related Resources on Science sites:
In Science Magazine
RESEARCH ARTICLES
The Status of the World's Land and Marine Mammals: Diversity, Threat, and KnowledgeScience 322 (5899), 225. [DOI: 10.1126/ Science.1165115