Warmer Winters Impact Hedgehog Hibernation and Health in Channel Islands

Wildlife specialists in the Channel Islands report that elevated temperatures are leading to a decrease in hedgehog hibernation and an increase in parasitic infestations among the animals. The Jersey Hedgehog Preservation Group (JHPG) indicated that milder winter conditions have allowed the mammals’ food sources to remain accessible, thereby reducing the necessity for hibernation. The Alderney Wildlife Trust (AWT) stated that higher temperatures are likely contributing to a rise in hedgehog parasites, which cause the creatures to be underweight and consequently require them to forage throughout the winter months. Historically, hedgehogs have been observed hibernating between November and mid-March in a winter nest, or hibernaculum, constructed from dry leaves and grass. Dru Burdon of the JHPG expressed her belief that the alteration in hibernation patterns is “due to climate change”. She commented: “We are not getting the cold winters we used to get, so there is no need for the hedgehogs to hibernate as their food is still available to them while the ground is not frozen.” She added: “If we get a few cold nights below 5C then they may hibernate or just stay in their nests for a bit, but they don’t seem to disappear for a long time in the winter like they used to.” Globally, 2023 was the warmest year ever recorded, and all nine of the warmest years have occurred since 2015. Guernsey experienced its second warmest year on record in 2023, according to the bailiwick’s Met Office. Jersey recorded its joint-hottest year on record in 2023, and average temperatures in the islands are higher than those in the mainland UK. Steve Byrne, the chief executive officer of the Guernsey Society for the Prevention of Cruelty to Animals (GSPCA), stated that it has become “incredibly difficult” for hedgehogs to hibernate because temperatures rarely fall below 5C (41F). He noted: “We see and rescue hedgehogs 365 days a year. Due to our weather and climate they are indeed awake all year round, as they would anywhere the temperature doesn’t drop to that required for them to go into hibernation mode.” Roland Gauvain, the chief executive officer of AWT, observed that some of the island’s bats, rats, and moles also appear to have changed their behavior. He commented: “We have anecdotal evidence that there are many more species, especially small mammals, which would historically have hibernated through the colder months of the year that are now remaining active throughout the winter. “This is not to say that significant numbers of hedgehogs do not still hibernate. “However, enough animals are now appearing to remain active, and therefore in sight of the general public, for the number of reports of ‘unseasonal activity’ to continue to climb.” He indicated that the cause of this behavioral shift is “likely to be complex,” though rising temperatures are “likely to be a significant factor.” He elaborated: “This could though be a combination of warmer winters making foraging more possible.” He further explained: “But it could also be wetter, warmer summers and autumn allowing hedgehogs to have multiple litters – making it more likely that there are underweight juvenile animals, and females, who need to continue to forage through the winter to gain or regain weight,” he explained. In November, Alderney’s Animal Welfare Society reported that it was caring for a “worryingly large number” of very sick hedgehogs. Veterinary nurse Kelly Huitson noted that some of these animals had been afflicted by ticks and displayed symptoms of an unidentified illness. Mr. Gauvain stated: “We can assume that warmer winters are also likely to benefit these parasites and may be responsible in part for increases, though this could also be down to introduction of new species into the island via various methods.” Fay Vass, chief executive of the British Hedgehog Preservation Society, mentioned that the current reports are anecdotal. She explained: “Hibernation is triggered by a variety of factors, two of which are temperatures and food availability. “So, if it remains warm and food is readily available it may be that hedgehogs hibernate for less time or possibly not at all – research would be needed to be able to say with any certainty that this is happening.”