{'fraction_non_alphanumeric': 0.027065527065527065, 'fraction_numerical': 0.027243589743589744, 'mean_word_length': 4.956521739130435, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 1, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Fate riding on their horns—and genes?

Themembers of the rhinoceros family—perennially in demand for their valuable horns—have posed challenges for conservation since the late 19th century. Their genetic diversity continues to be irretrievably lost. Meanwhile, some species are recovering, although their long-term future is not assured. So rhinos are a family of mixed fortunes. This issue of Oryx puts the focus on two living species of Asian rhinos. Goossens et al. (2013) address the plight of the Sumatran rhino Dicerorhinus sumatrensis, and Thapa et al. (2013), Subedi et al. (2013) and Murphy et al. (2013) address the recovery of the greater onehorned, or Indian, rhino Rhinoceros unicornis in Nepal. Currently, there are five living species of rhino—but only just! Two species in Asia, the Javan Rhinoceros sondaicus and the Sumatran, and one species in Africa, the black Diceros bicornis, are categorized as Critically Endangered on the IUCN Red List. The Indian rhino is categorized as Vulnerable and the white rhino Ceratotherium simum of Africa as Near Threatened. The Javan rhino, once widespread across lowland forests of South-east Asia, competed for land with increasingly dense human populations. The Indian subspecies R. sondaicus inermis became extinct before 1925. However, 30–50 individuals of the type subspecies have persisted in a single population under the protective shadow of Krakatoa on the western tip of Java since the 1930s. An even smaller population of c. 15 of the Vietnamese subspecies R. sondaicus annamiticus, thought extinct in the mid 1970s in a former war zone, was rediscovered in 1989. However, the last individual was found dead in 2010, with its nose hacked off (Brook et al., 2012)—like so many other rhinos killed for their horns in both Asia and Africa. Black rhinos were formerly widespread across sub-Saharan Africa but faced competition from bush clearance following European settlement. An onslaught of killing for their horns further decimated the continental population from perhaps 65,000 in the 1970s to , 2,500 in 2004. The species became locally extinct over much of Africa, and the western subspecies D. bicornis longipes continued its slide towards eventual extinction in Cameroon in 2011. The northern white rhino C. simum cottoni (which may be a separate species C. cottoni; Groves et al. 2010) became extinct in the wild in 2008. Persisting as a single population of c. 30 animals in an area of conflict between the Democratic Republic of Congo and Sudan, their long-term prospects had looked unpromising since the 1980s. However, prevarication delayed decisions over how to align the few remaining wild and captive rhinos. Finally, four of six rhinos remaining in captivity in the Czech Republic were transported to a Kenyan conservancy in 2009. Whether this remnant group can form an effective metapopulation through cross-breeding with the southern white rhino C. simum simum remains to be seen. In the light of two subspecies of rhinos becoming extinct and one subspecies, or possibly species, becoming extinct in the wild, during the last decade, Goossens et al. (2013) make radical proposals to ensure a future for the Sumatran rhino. This species was once widespread across steep, forested terrain in South-east Asia. Its slide towards extinction has passed largely undocumented but threats include forest loss and killing for their horns. Originally comprising three subspecies, the northern Sumatran rhino D. sumatrensis lasiotis of India and Myanmar has been extinct for several decades, while the Sumatran D. sumatrensis sumatrensis and the Bornean D. sumatrensis harrissoni subspecies have declined to a combined total of probably, 100 rhinos. In the 1980s some saw captive breeding in western zoos as the best hope for the survival of ‘doomed’ Sumatran rhinos. But several captive rhinos died in ex situ facilities and zoo births proved difficult to achieve, so the emphasis switched to breeding in sanctuaries in range. However, some sanctuary rhinos are too old to breed and some males are interrelated. With so few Sumatran rhinos remaining in fragmented wild populations, Goossens et al. (2013) propose collapsing the remaining populations of both subspecies (sumatrensis and harrissoni) into one breeding and management unit that prioritizes demography over genetic distinctiveness. They argue that further prevarication will only serve to ensure that the Sumatran rhino soon becomes extinct. IUCN convened the Sumatran Rhino Crisis Summit in March 2013 to broker agreement between the two range states of Indonesia and Malaysia. The Indian rhino and the white rhino have made strong recoveries after being reduced to very low numbers in the 1890s and early 1900s. The Indian rhino, so elegantly woodcut by Durer in 1515, was once widespread across the floodplains of the Ganges, Indus and Brahmaputra rivers. Rhinos were hunted heavily by native and colonial rulers during the 1800s and 1900s. In India, rhinos were reduced to remnant populations by the early 1900s. However, Kaziranga and a network of other protected areas were established from 1908 onwards and rhino numbers in India increased, to reach c. 2,300 by 2008. In contrast, Indian rhinos remained numerous in the Chitwan valley of Nepal until malaria was eradicated in the 1950s. Following land clearance for human settlement rhinos were hunted for their horns (Thapa et al., 2013). Even though afforded some protection, rhinos suffered a catastrophic decline NIGEL LEADER-WILLIAMS Department of Geography, University of Cambridge, Cambridge, UK. E-mail nl293@cam.ac.uk