Citizen Scientists Have Found the World’s Oldest European Hedgehog

A 16-year-old hedgehog called Thorvald was called the world’s oldest scientifically confirmed European hedgehog after he passed away. Citizen scientists found Thorvald in Denmark during a project monitoring the species. The citizens’ findings reveal insights on hedgehogs’ mortality, inbreeding, and life expectancy, and document Thorvald’s record-breaking age.

Thorvald the Hedgehog From Denmark

Sophie Lund Rasmussen, the lead author of the Wildlife Conservation Research Unit at Oxford University, expressed her joy at holding an individual that had lived for 16 years. She shared that this was great news for conservation and that her emotional reaction had caused some amusement among her colleagues.

According to research, the average hedgehog lives for approximately two years and faces a multitude of threats, such as habitat loss, pesticides, and predatory pets. The small mammals native to Europe have experienced a significant decline in population due to soil sealing, which hinders their ability to find vital food sources like worms and slugs. In the last two decades, surveys have revealed that the hedgehog population in the U.K. has dropped to less than one million, a sharp decline from about 30 million in the 1950s, as reported by the Natural History Museum in London.

Hedgehogs Face Environmental Challenges

Last year, Carsten Schiller, the head of the German conservation group Pro Igel, said that due to human activities, such as soil sealing, it is expected that the hedgehog population will decrease by up to 50% within a decade.

To get a better idea of how the animals are doing these days, 300 volunteers gathered data on about 700 deceased hedgehogs throughout Denmark as part of The Danish Hedgehog Project. The researchers determined the age of 388 hedgehogs by counting growth lines on their lower jawbones. A hedgehog would grow one over the winter, during hibernation. Prior to Thorvald, the oldest recorded hedgehog died at the age of nine. In addition to the 16-year-old record-breaker, the citizen scientists have found hedgehogs that had lived to 11 and 13. The data also suggests male hedgehogs live longer than females, which is not a trait found too often in mammals.

Hedgehog population declines have led to increased inbreeding, so scientists also looked into that and how it would affect the animals’ lifespans. Surprisingly, the study showed that inbreeding did not seem to affect it in general. Apparently, this study was one of the first thorough investigations concerning the effect of inbreeding on hedgehog longevity and indicated that if hedgehogs with a high degree of inbreeding manage to survive into adulthood, they do not experience a reduction in longevity. That was also a groundbreaking and positive discovery from a conservation perspective.