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Wednesday, 5 January, 2000, 13:27 GMT
Mexican prairie dog almost gone

prairie dog Trouble for one species spells problems for many

By Environment Correspondent Alex Kirby

A study of prairie dog numbers in northern Mexico has shown the animal's range has shrunk by more than half in the last five years.

The study, commissioned by the Chihuahuan Desert Programme of the World Wide Fund for Nature, was conducted by two biologists from the University of Nuevo Leon, Dr Laura Scott and Dr Eduardo Estrada.

The Mexican prairie dog, one of several species worldwide, is found only in the Chihuahua desert region. Its original distribution is estimated to have been an area of about 1,500 square kilometres.

A survey in 1995 found about 500 sq km of prairie dog colonies remaining.

Extinction fear

But the latest findings show the species' current distribution is only 216 sq km, a reduction of 55% since the earlier survey, and almost 86% less than the original range.

The animal is on the Red List of threatened species published by the International Union for the Conservation of Nature. WWF-Mexico says it is in danger of extinction.

Its concern is heightened by the role the prairie dog plays in the desert ecosystem, where it is described as a keystone species, whose disappearance would cause profound changes.

The animals form colonies that vary in extent from a few hectares to several hundred. They live in burrows with three or four openings to the surface in the form of a mound.

They perform an essential role in the maintenance of open grasslands, by controlling woody species such as mesquite and cactus.

Homes for other species

Without the prairie dogs' browsing, the plants could take over the grassland and create a new landscape.

The animals' burrows are also an important habitat for other species, including mammals like desert foxes and several birds, among them the mountain plover, ferruginous hawk and the burrowing owl.

WWF says many of the species that use the prairie dogs' colonies, including migratory birds, are themselves either threatened or endangered.

It says the main cause of the dogs' decline is a change in land use from pasture to agriculture, mainly for potatoes.

The large quantities of fertilisers and pesticides these crops need are themselves damaging land, water and wildlife.

WWF says most of the pasture land has been converted to farm use without the permits which are required under Mexican law.

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See also:
07 Jul 99 |  Sci/Tech
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