Female Tortoises Risk Death to Escape Aggressive Mates, Research Finds
A startling new study has uncovered a dramatic survival strategy among female Hermann's tortoises on a remote island in North Macedonia. Researchers have documented that female tortoises are literally walking off cliffs to escape sexually aggressive males, with some perishing in the process.
Imbalanced Population Creates Dangerous Dynamic
The research, published in the study Sex Ratio Bias Triggers Demographic Suicide in a Dense Tortoise Population, reveals a severe gender imbalance on Golem Grad island. In some areas, there are approximately 19 male tortoises for every single female, creating intense competition and aggression among males seeking mates.
Dr. Dragan Arsovski, an ecologist at the Macedonian Ecological Society who led the research, analyzed 16 years of data from the island population. The findings paint a grim picture of reproductive pressure so extreme that females are taking desperate measures to avoid persistent male attention.
Violent Mating Behavior Documented
Researchers observed male tortoises engaging in aggressive behaviors including bumping, biting, mounting, and violently poking fleeing females with their sharp tail tips. A majority of female tortoises examined showed injuries to their genital areas, evidence of the physical toll of constant harassment.
"She's literally buried by males," Arsovski told The New York Times, describing how multiple males would pursue a single female simultaneously.
Cliff Walking as Escape Strategy
The most dramatic finding involves female tortoises deliberately walking off high cliffs to escape their pursuers. While both males and females occasionally fall from cliffs, the study found a significantly higher proportion of females dying this way, suggesting it represents an intentional escape strategy rather than accidental falls.
This behavior, combined with reduced reproduction rates and lower survival rates among harassed females, has created what researchers describe as an "extinction vortex" for the female population on the island.
Unprecedented Natural Phenomenon
Jeanine Refsnider, an evolutionary ecologist at the University of Toledo who reviewed the study, expressed astonishment at the findings. "I've never heard of anything like that in a natural setting that doesn't involve human interference," she told The Times.
The research team predicts that if current trends continue, the last female tortoise on Golem Grad island could die by 2083, effectively dooming the local population to extinction without intervention.
Broader Implications for Wildlife Conservation
This study highlights how extreme population imbalances can trigger unexpected survival behaviors in animal populations. The findings may have implications for conservation efforts targeting other species facing similar gender ratio challenges in isolated environments.
Researchers continue to monitor the tortoise population while considering potential conservation strategies to address the dangerous gender imbalance and protect the remaining females from aggressive mating pressures.
