A 500-km long electrified fence officially aims to block the mixing of herds on common pasture, but some hope it will also keep out the thousands of Zimbabweans escaping poverty at home, who sneak cross the border looking for work in more prosperous Botswana. An estimated 36,000 illegal migrants were deported last year alone and, with xenophobia now firmly on the rise, Zimbabweans have become the target of a growing vigilante movement.