Oldest European Hedgehog Found by Citizen Scientists, Breaks Former Age Record By Seven Years
Michelle Milliken
European hedgehogs have faced dwindling numbers in recent years, so scientists in Denmark did some research on the species in an effort to promote helpful conservation plans. They sent volunteers out to find dead hedgehogs, and in the process, came across the oldest recorded member of the species, who was nearly twice the age of the prior record holder.
"The Danish Hedgehog Project" was launched in 2016, with the results published this month in the journal Animals. The citizen science initiative was led by Dr. Sophie Lund Rasmussen, alias "Dr. Hedgehog". In all, more than 400 volunteers across Denmark collected the bodies of just shy of 700 hedgehogs, 388 of which researchers were able to age through growth lines in the jawbone. One of the specimens was found to be 16-years-old, seven years older than the prior record holder for oldest European hedgehog. It was also more than eight times the average age of the specimens, just shy of two years.
Dr. Rasmussen, who is based at University of Oxford, says, "Although we saw a high proportion of individuals dying at the age of one year, our data also showed that if the individuals survived this life stage, they could potentially live to become 16 years old and produce offspring for several years. This may be because individual hedgehogs gradually gain more experience as they grow older. If they manage to survive to reach the age of two years or more, they would have likely learned to avoid dangers such as cars and predators."
Vehicles were found to be the main cause of death for the animals, which were collected in both rural and urban areas. About 56% were killed while crossing the road, 22% at a hedgehog rehabilitation center after being injured, and the remaining 22% died in the wild of natural causes. Their average age at death was 1.8 years, with males living longer than females, at 2.1 to 1.6 years, respectively. Around 30% died before they reached one year of age. There were also two other animals that had reached double digits, one 11 and one 13.
July was a particularly deadly month, with the highest traffic deaths recorded for males and females. This is the middle of their mating season in Denmark.
The researchers also took tissue samples to see if inbreeding impacted life expectancy. The team says past research had indicated that there was a low genetic diversity among Danish hedgehogs, but the study found that this did not appear to impact their lifespans.
Dr. Rasmussen says, "Sadly, many species of wildlife are in decline, which often results in increased inbreeding, as the decline limits the selection of suitable mates. This study is one of the first thorough investigations of the effect of inbreeding on longevity. Our research indicates that if the hedgehogs manage to survive into adulthood, despite their high degree of inbreeding, which may cause several potentially lethal, hereditary conditions, the inbreeding does not reduce their longevity. That is a rather groundbreaking discovery, and very positive news from a conservation perspective."
She hopes their work on this study will help develop more effective conservation management plans for the European hedgehog. Apart from vehicles, other threats the species faces include habitat loss and fragmentation.
