WE DEFLATED our tyres so that they could ooze through the Kalahari sand on our search for herds of wildlife migrating across the savannah. Eager ecologists from Australia, we scanned the horizons for dust clouds or heaving bodies. Instead, we were shocked to find that southern Africa’s great plains were mostly empty. We expected teeming herds of wildlife; we were confronted by a profusion of fences that sliced across the landscape.

We had not realised before our holiday visit in April and May this year that Africa’s iconic migrations are dying. Fifteen large mammals used to travel en masse across the continent, but five had already stopped by 2008, when the first migration audit was carried out. Most of those that remain are now in jeopardy, and the fences we encountered over and over again share the blame. My colleagues have warned of disastrous and far-reaching consequences, yet the problem has received relatively little attention from the international community.