Hedgehogs, a species that has been faced with many environmental changes during its life history. The woodland and grassland where its ancestors roamed has largely been replaced or fragmented by concrete and tarmac. However, new evidence suggests that the urban environment actually can still suit modern hedgehogs to some extent, and they are more at home in the city than we’d perhaps expect.
Urban hedgehogs have declined by one third and rural populations have declined by half since 2000. A disheartening figure overall, but also slightly unexpected. Why the slower decline in towns and cities? Researchers from the University of Hamburg have recently tried to understand why this difference in decline occurs, in the hope that further insights will aid in the conservation of the struggling species.
The team fitted temperature-sensitive transmitters to in order to track their movements and monitor their physiological changes.
“These specialised transmitters allowed us to monitor hibernation patterns and nest site use in winter, as well as activity and home range size in summer,” said lead researcher Dr Lisa Warnecke.
The researchers monitored hedgehogs near busy roads and quiet side streets, as well as those in the care of a local hedgehog sanctuary for comparison.
“We found that urban hedgehogs had much smaller nightly ranging areas than their rural counterparts — 5 hectares verses 50 — and that they adjusted their activity to levels of human disturbance,” says Dr Warnecke.
The urban hedgehogs stayed in private gardens for most of the day and were active during the night for mating and foraging, although not ranging as far as their rural relatives. This more cautious approach, alongside experience of how to navigate urban dangers and exploit food sources like scraps and cat food, could be contributing to the mammal’s slower decline in these areas.
The temperature sensitive transmitters also shed light on the hibernation patterns of both populations. In the winter months, hedgehogs enter a deep sleep, known as torpor, where their metabolic rate and body temperature significantly reduce in order to save energy.
“We were surprised to find that city hedgehogs showed hibernation patterns very similar to rural or captive populations in terms of the depth of torpor, the frequency with which they rewarmed and the overall duration of their hibernation,” said Warnecke. “This was despite city hedgehogs often nesting next to busy roads and having potential food sources available throughout winter ”
The authors highlight the importance of undisturbed ground cover for the survival of hedgehogs during hibernation in urban areas, whether this is garden parks or private gardens. Those living in the city can carry out some simple methods to ensure no harm to any hibernating hedgehogs in their garden.
“Gardens and public parks are very important for city hedgehogs,” says Dr Warnecke. “They need gardens with natural vegetation and public parks less immaculately pruned, with plenty of natural, bushy areas.”
Are hedgehogs adapting to an urban lifestyle? The picture isn’t clear. Since populations are declining across Britain, there is still more work to be done to completely unravel the mystery of how hedgehogs are seemingly settling in to city life somewhat, and the new evidence is a promising step in improving hedgehog conservation.
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The above article is based on materials provided by the Society for Experimental Biology.