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Cover : Our Lord's candle (Yucca whipplei) occurs in southern California (U.S.A.) and the southwestern Mojave Desert. Several subspecies are restricted to particular geographic locations or floristic provinces. On pages 672‐679, Ferreira and Boldrini review the history of the concept of endemism as it applies to plants. They emphasize that lack of standardization of the geographic extent of endemism complicates classification of species as endemic. On pages 708‐715, Geyer et al. present a method of classifying stresses from climate change that affect different levels of biological organization. Probabilities of persistence of endemic taxa are expected to be highly affected by climate change. Cover image © 2011 Tim Laman. Photographer : Tim Laman ( http://www.TimLaman.com ) is a field biologist and wildlife photojournalist with a Ph.D. from Harvard University. Since 1987, the focus of his scientific research and photography has been the rainforests of Borneo and the Asia‐Pacific region. He is a regular contributor to National Geographic and has published 18 articles in that magazine on topics ranging from endangered species to regions of high species richness under intense pressure from human activities. Tim has also published more than a dozen scientific articles related to rainforest ecology and ornithology. He has a reputation for successfully capturing elusive and critically endangered species in his photographs.     

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Cover: Climate-change models project warmer air temperatures worldwide (upper left) and decreased summertime precipitation in many regions (upper right), which could result in warmer streams and lower water levels. Such conditions may facilitate the expansion of invasive species, such as this signal crayfish ( Pacifastacus leniusculis ) (photo by Jeremy Monroe, Freshwaters Illustrated). See Special Section, pages 518–592.     

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Cover: Tanzania contains one of Africa's "hottest" biodiversity hotspots and some of its oldest, largest, and best-protected national parks. It also has a long tradition of wildlife research."The Value of Long-Term Research: Conservation Science and Practice in Tanzania," a special section, explores the contribution of conservation science to conservation practice. Photos by Felix Borner, Sarah Durant, and Karyl Whitman. See pages 576-667.     

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Cover: During winter in the interior of Yellowstone National Park most elk migrate from deep snow while many bison do not, existing near thermal areas and on wind-blown ridges. Wolves still attempt to kill these bison and often spend hours making a kill. Wolf-bison systems used to dominate in North America prior to European settlement but now only Yellowstone and Wood Buffalo National Parks have intact wolf-bison systems. See pp. 1105-1116. Photo by Doug Smith, National Park Service.     

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Cover: Recreational fishers can be instrumental in successful fisheries conservation projects, thereby reducing fisheries declines. In Mongolia's Eg‐Ur watershed, recreational anglers, local citizens, and scientists have teamed up to protect the world's largest salmonid, Hucho taimen. Photo by Sudeep Chandra. See pages 1125–1134.     

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Cover: A poster of the Ivory‐billed Woodpecker (Campephilus principalis) decorates the wall of a restaurant in Brinkley, Arkansas (U.S.A.). The town is located near where the bird was reportedly sighted in 2004, 60 years after its presumed extinction. Th ree papers in this issue present new methods to estimate whether species are extinct. On pages 47‐56, Gotelli et al. introduce a statistical method for estimating the probability of species persistence from the temporal sequence of collection dates of museum specimens. Application of the method to a case study of the Ivory‐billed Woodpecker suggests there is virtually no chance the species is currently extant within its historical range in the southeastern United States. On pages 180‐184, Solow et al. describe a Bayesian method that formally accounts for species records of uncertain validity. They used a recently published record of sightings of the Ivory‐billed Woodpecker to illustrate their method. Their results were consistent with the conclusion that the species is extinct, but did not provide a clear estimate of the time of extinction. On pages 57‐67, Fisher and Blomberg outline how to estimate the probability that species with few records or recent last‐sighting dates are extinct. Cover image © 2012 Joel Sartore. Photographer: During more than 20 years with the National Geographic Society, Joel Sartore ( http://www.joelsartore.com ) has covered topics from the Amazon rainforest to beer‐drinking, mountain‐racing. firefighters in the United Kingdom. His work focuses on endangered species, natural history, and land use. Joel's books include Photographing Your Family, Face to Face with Grizzlies, Nebraska: Under a Big Red Sky, RARE: Portraits of America's Endangered Species, and, most recently, Let's Be Reasonable. In addition to his work for National Geographic, Joel has completed assignments for Audubon Magazine, Time, Life, Newsweek, and Sports Illustrated and has contributed to numerous book projects. Joel and his work have been the subject of several national broadcasts in the United States, including National Geographic's Explorer, NBC Nightly News, NPR's Weekend Edition, and an hour‐long PBS documentary. He is a regular contributor to the CBS Sunday Morning Show.     

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Cover: Hunting of endangered species, especially large primates, by Matsigenka indigenous people living in Manu National Park, Peru, has prompted debate over whether indigenous populations living in tropical parks have the potential to be conservation partners or should be treated as threats to biodiversity conservation. Participatory monitoring of hunting in the park showed that even after decades of subsistence hunting and localized depletion, large primates and other vulnerable species continue to be hunted at high rates, indicating source-sink dynamics and suggesting that there is time to devise a co-management plan. See pages 1174–1185. Photos by Glenn Shepard Jr. (top) and Julia Ohl (bottom).     

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Cover : A local boy spearfishing in Wakatobi Marine National Park, Sulawesi, Indonesia, 2004. Octopus, grouper, fusilier, and scorpionfish commonly are fished in the area. Customary management systems that limit fishing can increase the biomass of fishes targeted by local fishers. Feary et al. (pp. 341‐349) found that customary closures affect the distance at which a fish begins to flee an approaching threat. This flight distance, in turn, can influence local fishing success. However, the accuracy of conventional techniques used by scientists for censusing reef fishes do not appear to be affected by changes in flight behavior associated with fishing.