Talk notes: Studying an urban mammal, the West European hedgehog

A large crowd gathered for the first evening talk of the 2024/25 programme of events by Tisbury and District Natural History Society and, unusually, after the notices and a welcome to our speaker had been given, an audience member told an anecdote related to the subject. Many years ago, in a terraced house in London, Mike awoke in the middle of the night to find a hedgehog snuffling around his pillow! How did it get there? Mike hoped that Abi might enlighten him!

Dr Abi Gazzard has spent many years studying hedgehogs in Earley, Reading as the subject of her Masters and PHD. She now works for the Durrell Wildlife Conservation Trust. Abi’s talk was divided into four sections:

The hedgehog family
Research: garden use
Research: nest box studies
Hedgehogs: research and you!

Hedgehogs are members of the erinaceidae family. This makes them close relatives of moles and shrews. They are NOT rodents. Not all hedgehogs are spiny and there are nineteen types of hedgehog known today – the most recent was identified as recently as December 2023. Hedgehogs are: nocturnal, solitary, not territorial, weigh between 500g and 1500g, primarily insectivorous, build nests under cover and hibernate during the winter.

Citizen science surveys have shown a steep and rapid decline in population sizes over the past twenty years in rural areas however, in urban areas, the population numbers appear to be stable. There is limited knowledge about the answers to why numbers are decreasing in rural areas or stabilising in urban areas.

Abi’s research area was in Earley, Reading, a suburban area with mixed, high density housing and no badgers (badgers are the major predators of hedgehogs).

She used GPS and radio tags to track the hedgehogs in the area. The surveys were nocturnal and also relied heavily on community engagement. Abi observed twenty-eight hedgehogs over nine nights each. A male hedgehog visited three front gardens and nine back gardens and covered a distance of 3.5 hectares per night while the female hedgehogs visited an average of five front gardens and seven back gardens and covered 0.7 hectares per night. Both sexes preferred the garden of terraced houses. Amenity grassland was less preferred to gardens.

The factors which affected the time spent in gardens negatively were a lack of access between the front and back garden, foxes, rainfall and plentiful other gardens nearby.

The positive factors were shorter nights (summer), supplementary feeding and compost heaps. Abi posed the question, does supplementary feeding result in the thriving urban population? We do not know the answer. More research is needed.

Abi then turned to the question, what makes a good nest box?

There were over five thousand responses to a hedgehog housing census. The use of hedgehog houses was found to be linked to garden factors, nest box placement and resource providing. A good hedgehog house depends on the design and also microclimates.

There are significant research gaps in:- nest box efficiency, supplementary feeding, population parameters, urban hazards and rural hedgehogs.

What can you do to help?
If you are a garden owner you could consider any hazards, the connectivity between gardens, providing food and shelter; you could log sightings; look out for sick and injured hedgehogs and take them to a hedgehog rescue; take part in a questionnaire, survey and other citizen science project.

Spread the message!

​Emma Procter