On the island of Golem Grad, in Lake Prespa in North Macedonia, there are almost 1,000 Hermann’s tortoises. The problem: for every female, there are 19 males. The result is so extreme that scientists documented it for 16 years before publishing it in the journal Ecology Letters: the females flee the constant sexual pursuit and, when they reach the edge of the cliff, they do not stop. They throw themselves into the void.
It is not a metaphor. One female monitored with GPS recorded a sudden acceleration just before plunging down; the shell hit the rocks with fractures. In experiments with simulated edges, the female tortoises of Golem Grad kept moving forward when they were being pursued, while those from the mainland braked before falling. The collective pressure from the males even altered that basic survival instinct. 🐢
Ecologist Dragan Arsovski, who began the monitoring in 2008, and his team describe the process as an ‘extinction vortex’: fewer females generate more proportional pressure from males, which kills more females, which further increases the pressure. It is a cycle with no way out, and the projection already has a name and a year: the last female on the island will die in 2083. It is the first case of this kind documented in nature without any human intervention.