Life on the edge

Wild horses in Namibia

source: Roman Goergen
New Scientist August 25 2001
starts p30, 4 pages long

There are some 100 wild horses living in the Namib Desert, Namibia, the only population of wild horses in the whole of Africa. The population had dropped to 70 horses in 1999, as the result of a drought, and farmer, Piet Swiegers, sought to help them by taking alfalfa bales for them to eat, until heavy rains saved them.

The horses have been able to survive extreme conditions, including droughts, commonplace in the region, as well as temperature fluctuations, from zero at night to 40 degrees C in the daytime in shady places during the summer. The winter weather can be very hot one week, followed by freezing rain a week afterwards.

The origin of the horses is unknown. Some stories tell of German cavalry officers releasing horses in the 1900s, while others mention horses released by German railroad builders. The horses drink from a stone trough at a disused railway station built by German troops at the start of the 20th century.

Telane Greyling is a researcher from Potchefstroom University, South Africa, and he has studied these horses’ behaviour. He calculates that they have been wild for between 80 and 100 years, or 10 generations.

University of Kentucky’s Gus Cothran has analysed blood samples from these horses, and found a factor called q which is unique to the Namib horses. He also found them to be highly inbred. They show the greatest similarity with Shagyas, or Arab horses from Poland, and US Arab horses, so the Namib and European horse breeds appear to have a common ancestry.

The horses’ appearance is likely to have been affected by the extreme conditions they live in. They are from 1.4 metres to 1.5 metres high, when standing, measured at the withers, but their forbears could have been some 10 cm taller. They also have very thick coats in winter, which helps them to survive the bitter cold of that season. Their behaviour has also changed, and they seem to drink as much water as horses elsewhere, but drink less frequently, at intervals of between 30 hours and 72 hours, sometimes waiting as long as 100 hours for a drink. They graze an average of 17 hours daily when grazing is available, compared with 13 hours for Camargue horses from France. This could be because grazing is poor in the desert, so they need to graze for longer.

The horses are trapped where they live. They are tied by the water trough, and hemmed in by mountainous and other natural barriers, as well as fenced farmland. The Environment Ministry of Namibia feeds them at times of drought, as do farmers. Critics argue that the horses should be abandoned to die if they are unable to adapt, but the problems they face are partly man-made, as land has increasingly been fenced in, which means that the horses cannot easily escape drought. Gazelle and oryx herds have disappeared from the desert, and human activity has been a factor in their disappearance. The Namib horses appear to be healthy and strong, but are still under threat over the longer term, and their survival depends on human activity.