How many hedgehogs are left?

Counting hedgehogs is difficult

In the 1950s it was estimated there were 36.5 million hedgehogs in Britain based on extrapolating up from a density of 2.5 animals/ha (one per acre), but this was based on limited data and is probably an overestimate. 

A more recent estimate in 1995 of 1,550,000 in Great Britain (England 1,100,000, Scotland 310,000, Wales 140,000) is more reliable, but still has a high degree of uncertainty as it was based on very limited information about hedgehog density estimates for different habitat types. There is now evidence that numbers have been declining since then.

Graph of the decline of hedgehogs based on occurrence figures from PTES' Mammals on Roads and Living with Mammals surveys

However, it should be noted that there is still no reliable method for estimating the abundance (= numbers) of hedgehogs in an area. Marking animals ("Mark-Release-Recapature") can work for isolated populations, but is not yet a verified method for all scenarios.

Questions about urban areas

One key area of uncertainty is in understanding the average density of hedgehogs in urban areas, which equate to around ten percent of the land area in the UK. Small differences in this have a significant effect on the total population estimate.

It is difficult to work out an accurate value because of the range seen in the wild: e.g. central London has almost no hedgehogs, but some suburban neighbourhoods have more animals per hectare than anywhere else.

Long running mammal surveys are very important

Three surveys by the British Trust for Ornithology and PTES’ Mammals on Roads and Living with Mammals surveys all indicate downward trends in hedgehog populations.

We appear to have lost around 30% of the population since 2002 and therefore it seems likely that there are now fewer than a million hedgehogs left in the UK.

Hedgehogs now appear to be declining in the UK at the same rate as tigers are globally – at around 5% a year, both in rural and urban habitats.

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