Hedgehogs’ hibernation patterns show surprising flexibility

Research has found hedgehogs living in the same, semi-rural area have wide variation in hibernation timing and pattern, with some entering hibernation as much as three months later than others. The researchers say this flexibility could help them adapt to climate change and urbanization.

In a new study, researchers at Liverpool John Moores University monitored the hibernation patterns of wild hedgehogs living on a disused golf course on the Wirral. The research, which is yet to be published, was presented at the British Ecological Society’s (BES) Annual meeting in Liverpool on the 11th December.

Using a combination of radio trackers that could both locate the animals and record their skin temperature, along with late-night torch-lit walks, this is the first study to reveal the surprisingly diverse hibernation patterns of wild hedgehog hibernation in this level of detail.

All five radio-tracked hedgehogs in the study underwent hibernation but the researchers observed variations of up to 93 days in hibernation start date and 47 days in hibernation end date between individuals.

“It was a surprise to see wild hedgehogs living in the same environment have so much variation in their hibernation pattern,” said Katie Crawford, a Ph.D. student at John Moores University who will present the research at the BES Annual Meeting.

“The first hedgehog started hibernating in mid-September, when it was 19°C (a very high temperature to hibernate in) and another didn’t enter hibernation until mid-December when temperatures were as low as -6°C (a very low temperature for them to still be active).”

When hedgehogs hibernate, they go through cycles of torpor in which they decrease their metabolic rate and body temperature. Torpor bouts, typically lasting a few days to weeks, are interspersed with bursts of arousal for a few hours up to a couple of days.

However, in the study, the researchers found that some individuals used short torpor phases followed by extended phases of activity, in which animals were likely foraging, for up to five days at the start and end of the hibernation period.

The researchers say that this flexible approach to hibernation could help hedgehogs adapt to changing environmental conditions.

“Hibernators are at significant risk from climate change because they’re very reliant on ambient temperatures. When temperatures are higher, they can’t save as much energy because they’re not reducing their body temperature as low,” explained Katie. This can be problematic, as when they hibernate, they live off their fat reserves.

“But if hedgehogs are using flexible hibernation strategies to ensure they’re obtaining enough food, this could help them as winters in the UK get milder and less predictable.”

European hedgehogs have recently been upgraded to near threatened status in the IUCN Red List, with road collisions being one of the main threats to them in the UK. Populations in rural areas of the UK are in decline while urban populations are stable and increasing in some areas.

Describing the experiment which took place from Spring 2023 to Spring 2024, Katie said, “At the start of the experiment we would go out to the golf course at night with big torches to find hedgehogs. The population there was really quite high, with around 26 individuals just on this golf course over the summer.

“With the help of my supervisor, Dr. Julia Nowack, we tagged a subset of them with radio tags and then monitored them daily from when they started hibernating to when they finished.”

The researchers caution that with only five hedgehogs, the sample size is small. This is due to the intensive nature of the research, making it hard to monitor more individuals to this level of detail.

The researchers are currently running a follow-up experiment in which they tagged 11 hedgehogs in different habitats across the Merseyside region to see whether animals in urban areas show even higher variations. “We’re already seeing a lot of flexibility in the hibernation patterns of this year’s cohort,” added Katie.