Hedgehogs are well-known and popular wild animals that have lived on earth for around 20 million years. When examining the spiny species, a team of researchers not only finds out which stage of life is particularly dangerous for hedgehogs, they also discover an unusually old animal.
A team of researchers in Denmark has discovered the world's oldest hedgehog. Erinaceus europaeus was discovered by accident while examining dead animals. According to the researchers, he is 16 years old and therefore surprisingly old. "We found the oldest scientifically confirmed hedgehogs in Europe in our samples (11, 13 and 16 years), with previous research showing a maximum age of 9 years," writes the team of the results, which are published in the MDPI special issue "Tiere " have appeared.
The average life expectancy of hedgehogs is two to four years. Juvenile mortality is classified as high for the species. Apparently, the majority of animals die on the road. In exceptional cases, hedgehogs can reach an age of seven to eight years, writes the Austrian Nature Conservation Union.
Since the number of hedgehogs living in Europe has decreased dramatically in recent years and researchers know relatively little about the wild animals and the populations living in Europe, the team led by Sophie Lund Rasmussen from the University of Aalborg started "The Danish Hedgehog Project". In 2016, the population was called upon to collect and send in animals that had been found dead. The biologists working with Rasmussen, who also belong to the Wildlife Conservation Research Unit at the University of Oxford, received a total of 697 dead hedgehogs, which they examined in detail as part of the project.
The examination also included the removal of the jawbones. On these you can see growth lines that reveal the age of the animals. Growth lines appear because the growth of the animals is stopped during their hibernation. The researchers were able to obtain a total of 388 jawbones for the study. The biologists not only found the particularly old animals, but also determined data on the general life expectancy of the animals.
It turned out that around a third of the animals examined had died before the age of one year, reports the University of Oxford. Most of them, 56 percent, were run over by cars crossing the street, and 22 percent died in a hedgehog sanctuary. Attempts are made to nurse sick and injured animals back to health. According to the announcement, 22 percent also died of natural causes. How many hedgehogs fall victim to predators in the wild remains unclear.
The determined average life expectancy of the examined hedgehogs was given as 1.8 years. The research team can thus confirm the high juvenile mortality rate of hedgehogs. As a reason, Rasmussen names a particularly frequent parasite infestation in young hedgehogs, but also the lack of experience to recognize dangers. "Hedgehogs only gain experience over time. If they have survived to the age of two or more, they have probably already learned to avoid threats from cars and predators," sums up the biologist.
And another finding is interesting: unlike other mammals or humans, male hedgehogs live on average 0.5 years longer than female hedgehogs. The researchers assume that male hedgehogs have it easier overall than their female counterparts. "Hedgehogs are not territorial and therefore rarely have to fight. The females, on the other hand, are solely responsible for raising their young," explains the biologist. But males are more likely to be road traffic victims than females, especially in the summer month of July, which is considered to be the peak mating season for hedgehogs in Denmark.
In addition, when examining tissue samples, the researchers recognize a high degree of inbreeding within the Danish populations. Although inbreeding is generally recognized as a risk factor for the health and life expectancy of populations, it does not appear to have a negative impact on the life expectancy of the animals here. "Our research shows that if hedgehogs are able to survive to adulthood despite their high level of inbreeding, which can cause several potentially fatal hereditary diseases, inbreeding does not reduce their longevity. This is quite a groundbreaking discovery and very positive news to come out of." view of nature conservation", summarizes the research team.
