Updated: Sep 27, 2018
There are many reasons why the hedgehog population has decreased so much in the UK, some obvious and some not so. I'll list the ones I know off and the ones that others have found out though research.
Building Works / Extensions / Garden Landscaping:
I have personally noticed alot of the hedgehogs we receive here at Hornbeam Wood Hedgehog Sanctuary during the Spring and Summer months come from spots where a house was being renovated, extended, cleared out, the gardens where being landscaped, or more often the hedges where being cut back or totally removed. Most of the time they are hoglets who arrive with no mother, some still with their eyes closed. Man made buildings often make good nesting grounds for hedgehogs especially garages! Lots of mess, old covers, and warmth all of which hedgehogs will love.
The problem comes when the mother is disturbed, she will either run off and abandon the hoglets or stick around and potentially eat them! When the hoglets are only days or weeks old they need their mother as they cannot eat solid foods. If they are left, they will almost certainly die.
There is not alot that can be done about this situation other than making people aware of this and hoping if they do spot a nesting hedgehog that is disturbed to get in contact with someone who can help them asap.
Modern farming is associated with practices that are likely to have negatively affected hedgehogs, such as the destruction of hedgerows to create larger fields and the use of chemicals which might reduce the availability of their insect and other bug prey.
This also goes for the gardeners out there who use slug pellets or any other toxic substance to save their fruit and veg from insects. The problem here is hedgehogs also eat these poisons and as a result are likely to be seriously ill or die. It also reduces food available to them as hedgehogs eat alot of the bugs and slugs.
Another common scenario I have noticed that kills hedgehogs is the plastic thin netting used on veg to keep birds or other animals off of the veg. This netting is a death trap for the spiky hedgehog as they get tangled up in it. They strugle making it worse and eventually become trapped.
An increase in badgers:
Badgers are the only animals that can unroll and kill hedgehogs. Their numbers have increased by more than 85% since the mid-1980s. This means they are killing and consuming more hedgehogs bringing the hedgehog population down.
An increase in roads and traffic:
Collisions with vehicles is one of the most common forms of mortality in hedgehog populations. Roads may also act as barriers to the movement of hedgehogs, isolating populations and making them more vulnerable to dying off in that area.
Alot of man made structures that are put in place to prevent cars going down certain roads or to stop noise from travelling from motorways in to urban housing estates also stop hedgehogs from roaming about or worse isolate them being unable to mate or escape.
This also goes for home owners who have open holes such as drains which the hedgehogs can fall down but cannot get out. Along with home owners genrally putting up fencing that has no holes to allow hedgehogs to both escape out of and roam in though.
Changes to our climate during the summer could reduce the ability of hedgehogs to build up enough fat reserves prior to hibernation. Changes during the winter might make them more likely to come out of hibernation when there is little or no food available.
Furthermore, localised flooding is also likely to pose a risk to hedgehogs which are breeding or hibernating in nests on the ground.
There are lots of ways you can take action right now to help our hedghogs,