SA Forum is an invited essay from experts on topical issues in science and technology.
Crowds love black-and-white animals. Perhaps the sharp contrast of light and dark conjures long-lost memories of how the world looks to people in their first weeks of life. Whatever the explanation, we’re often transfixed by the sight of zebras, orcas, giant pandas—and especially by the presence of white tigers. Just ask the Las Vegas entertainers Siegfried and Roy.
Sometimes the attraction turns fatal, as it did a couple of weeks ago for a young man who toppled into a Delhi zoo’s tiger enclosure. But long before that deadly incident animal welfare advocates began disputing the wisdom of raising white tigers. More than 30 years ago William Conway, director of the then New York Zoological Society (now known as the Wildlife Conservation Society), became convinced that the rare cats were merely the victims of a hereditary defect that was propagated because the animals were kept and deliberately bred as glorified sideshow exhibits. “White tigers are freaks,” he declared more than 30 years ago. “It’s not the role of a zoo to show two-headed calves and white tigers.” Three years ago the Association of Zoos and Aquariums endorsed that opinion, instructing all AZA members to cease any breeding (pdf) of captive white tigers.
The truth is that white tigers are the product of a rare but naturally occurring genetic variant within the wild Bengal population. Even so, the experts’ confusion about the subject has been understandable, given the previous lack of precise information on the white tiger’s genetic roots. It was only last year that our team published the workcracking the mystery at last.
Using state-of-the-art genetic tools we scanned the entire genome of a family of Bengal tigers that included orange and white individuals alike and validated our findings against data from 130 unrelated members of the same species. The result was crystal clear: The white tiger’s distinguishing characteristic arises from a single mutation, the substitution of one amino acid for another—valine for alanine—in the “solute carrier” protein geneticists call SLC45A2. Its job is basically to transfer specific molecules across cellular barriers.
Similar variations in SLC45A2 have been observed in other vertebrate species ranging from humans to chickens. With rare exceptions the swap’s only effect on the animal is a decrease of external pigmentation. That’s what makes the white tiger white. And until trophy-hunting humans came along the mutation made little difference to the animals’ ability to survive and reproduce—most of its prey species are color blind.
Records dating back at least four centuries indicate that wild white tigers once prowled freely in the forests of India. Some were shot, others were captured and sent to royal menageries and still others remained in the jungles to perpetuate their lineage. The last known specimen in the wild was shot dead in 1958, leaving behind only the captive breeding population. Trophy hunting, habitat loss and habitat fragmentation drove the rest to extinction.
Almost all of the white Bengals alive today are descended from a solitary male cub that was captured in 1951. Deliberate inbreeding has maintained the animals’ recessive coloration but it also has led inevitably to a whole range of health problems that helped inspire William Conway’s “two-headed calves” overstatement. In fact, observations of 52 white tigers born in the U.S. at the Cincinnati Zoo detected no significant heritable defects other than some weakness in the animals’ eyesight
In any case, we now know how to reduce or eliminate the problems that have arisen from inbreeding among white tigers. Now that the crucial mutation has been identified, it will be possible to identify and crossbreed pairs of Bengal tigers, each one possessing a single copy of the recessive gene. Basic Mendelian rules give a 25 percent probability that any given pregnancy will produce white-tiger offspring while significantly expanding the gene pool of healthy animals.
And recognizing that white tigers are part of the natural genetic diversity of their species, we humans should consider saving them. Well-managed captive populations of wild animals have proved to be valuable assets in education, research and fund-raising—and they can serve as genetic reservoirs for the planet’s dwindling wild species.
No one knows how many centuries—quite possibly millennia—white tigers lived freely in their natural habitat before human hunters eradicated them. Doesn’t our species now have a responsibility to maintain at least a few white Bengals in good genetic health?
Project Tiger is a tiger conservation programme launched on 1 April 1973 by the Government of India during Prime MinisterIndira Gandhi's tenure. The project aims at ensuring a viable population of Bengal tigers in their natural habitats and also to protect them from extinction, and preserving areas of biological importance as a natural heritage forever represented as close as possible the diversity of ecosystems across the tiger's distribution in the country. The project's task force visualized these tiger reserves as breeding nuclei, from which surplus animals would migrate to adjacent forests. The Funds and commitment were mastered to support the intensive program of habitat protection and rehabilitation under the project. The government has set up a Tiger Protection Force to combat poachers and funded relocation of villagers to minimize human-tiger conflicts.
During the tiger census of 2006, a new methodology was used extrapolating site-specific densities of tigers, their co-predators and prey derived from camera trap and sign surveys using GIS. Based on the result of these surveys, the total tiger population has been estimated at 1,411 individuals ranging from 1,165 to 1,657 adult and sub-adult tigers of more than 1.5 years of age. Owing to the project, the number of tigers has improved to 2,226 as per the latest census report released on 20 January 2015.
Project tiger's main aim was to:
- Limit factors that leads to reduction of tiger habitats and to mitigate them by suitable management. The damages done to the habitat were to be rectified so as to facilitate the recovery of the ecosystem to the maximum possible extent.
- To ensure a viable population of tigers for economic, scientific, cultural, aesthetic and ecological values.
The Indian tiger population at the turn of the 20th century was estimated at 20,000 to 40,000 individuals. The first country-wide tiger census conducted in 1972 estimated the population to comprise a little more than 1,800 individuals, a reduction in tiger population.
In 1973, the project was launched in the Corbett National Park of Uttarakhand.
Project Tiger is administered by the National Tiger Conservation Authority. The overall administration of the project is monitored by a steering committee headed by a director. A field director is appointed for each reserve, who is assisted by a group of field and technical personnel.
- Shivalik-terai conservation unit
- North-East conservation unit
- Sunderbans conservation unit
- Western ghats conservation unit
- Eastern ghats conservation unit
- Central India conservation unit
- Sariska conservation unit
- Kaziranga Conservation Unit
The various tiger reserves were created in the country based on 'core-buffer' strategy:
1.Core area: The core areas are freed of all human activities.It has the legal status of a national park or wildlife sanctuary.It is kept free of biotic disturbances and forestry operations like collection of minor forest produce,grazing,and other human disturbances are not allowed within.
2.Buffer areas:The buffer areas are subjected to 'conservation-oriented land use'. It comprises forest and non-forest land.It is a multi-purpose use area with twin objectives of providing habitat supplement to spillover population of wild animals from core conservation unit and to provide site specific co-developmental inputs to surrounding villages for relieving their impact on core area. For each tiger reserve, management plans were drawn up based on the following principles:
- Elimination of all forms of human exploitation and biotic disturbance from the core area and rationalization of activities in the buffer zone
- Restricting the habitat management only to repair the damages done to the ecosystem by human and other interferences so as to facilitate recovery of the ecosystem to its natural state
- Monitoring the faunal and floral changes over time and carrying out research about wildlife
By the late 1980s, the initial nine reserves covering an area of 9,115 square kilometers (3,519 square miles) had been increased to 15 reserves covering an area of 24,700 km2 (9,500 sq mi). More than 1100 tigers were estimated to inhabit the reserves by 1984. By 1997, 23 tiger reserves encompassed an area of 33,000 km2 (13,000 sq mi), but the fate of tiger habitat outside the reserves was precarious, due to pressure on habitat, incessant poaching and large-scale development projects such as dams, industry and mines.
Wireless communication systems and outstation patrol camps have been developed within the tiger reserves, due to which poaching has declined considerably. Fire protection is effectively done by suitable preventive and control measures. Voluntary Village relocation has been done in many reserves, especially from the core, area. Live stock grazing has been controlled to a great extent in the tiger reserves. Various compensatory developmental works have improved the water regime and the ground and field level vegetation, thereby increasing the animal density. Research data pertaining to vegetation changes are also available from many reserves. Future plans include use of advanced information and communication technology in wildlife protection and crime management in tiger reserves, GIS based digitized database development and devising a new tiger habitat and population evaluation system.
Controversies and problems
Project Tiger's efforts were hampered by poaching, as well as debacles and irregularities in Sariska and Namdapha, both of which were reported extensively in the Indian media. The Forest Rights Act passed by the Indian government in 2006 recognizes the rights of some forest dwelling communities in forest areas. This has led to controversy over implications of such recognition for tiger conservation. Some have argued that this is problematic as it will increase conflict and opportunities for poaching; some also assert that "tigers and humans cannot co-exist". Others argue that this is a limited perspective that overlooks the reality of human-tiger coexistence and the role of abuse of power by authorities, rather than local people, in the tiger crisis. This position was supported by the Government of India's Tiger Task Force, and is also taken by some forest dwellers' organizations.
- ^ abcPanwar, H. S. (1987). "Project Tiger: The reserves, the tigers, and their future". In Tilson, R. L.; Sel, U. S. Tigers of the world: the biology, biopolitics, management, and conservation of an endangered species. Park Ridge, N.J.: Minnesota Zoological Garden, IUCN/SSC Captive Breeding Group, IUCN/SSC Cat Specialist Group. pp. 110–117.
- ^Jhala, Y. V., Gopal, R., Qureshi, Q. (eds.) (2008). Status of the Tigers, Co-predators, and Prey in India(PDF). TR 08/001. National Tiger Conservation Authority, Govt. of India, New Delhi; Wildlife Institute of India, Dehradun. Archived from the original(PDF) on 2 June 2013.
- ^"Tiger population grows". CNN IBN.
- ^Thapar, V. (1999). The tragedy of the Indian tiger: starting from scratch. In: Seidensticker, J., Christie, S., Jackson, P. (eds.) Riding the Tiger. Tiger Conservation in human-dominated landscapes. Cambridge University Press, Cambridge. hardback ISBN 0-521-64057-1, paperback ISBN 0-521-64835-1. pp. 296–306.
- ^Buncombe, A. (31 October 2007) The face of a doomed species. The Independent
- ^Strahorn, Eric A. (2009-01-01). An Environmental History of Postcolonial North India: The Himalayan Tarai in Uttar Pradesh and Uttaranchal. Peter Lang. p. 118. ISBN 9781433105807.
- ^Government of India (2005) Tiger Task Force ReportArchived 27 March 2009 at the Wayback Machine..
- ^Campaign for Survival and Dignity Tiger Conservation: A Disaster in the MakingArchived 11 July 2011 at the Wayback Machine.. forestrightsact.com