Increases in hedgehogs are related to decreases in breeding bird success?

The Uists cull has already cost more than £1m, but we should question the causal link between bird and hedgehog populations. While some hedgehogs might eat some birds’ eggs, that does not mean there is a causal link between increases in hedgehogs and decreases in breeding bird success.

hebridean hedgehogs-a prickly issue

How much is a hedgehog worth? Two stories with very different values attached to hedgehogs in the space of two days.

First, the Guardian carried an interview with Caroline Gould of the Vale Wildlife Rescue. The thousands of animals, including many hundreds of hedgehogs, that are brought to her each year need feeding, yet money from charitable trusts and public donations is in decline. It costs about £5 a week to feed a hedgehog in care.

The other, published in the Scotsman, revealed a very different value attached to the hedgehog: more than £800 each as they were first killed and then translocated by Scottish Natural Heritage from the Uists in the Outer Hebrides. This was part of an attempt to eradicate the prickly interlopers that had been introduced in 1974 in a misguided act of biological control of slugs and snails. As the numbers of hedgehogs spread across these islands, so the breeding success of many of the internationally important populations of wading birds decreased. A link was made – hedgehogs are partial to eggs, and these hedgehogs were emerging from hibernation just as the birds were laying a smorgasbord of delight.

SNH felt obliged to act and in 2003 began a cull of hedgehogs, which in turn generated an enormous outcry from the public and the establishment of Uist Hedgehog Rescue. Fortunately, after some research into the behaviour of translocated hedgehogs, SNH decided to work with the rescuers and stopped killing – and they begin searching for hedgehogs again this spring.

But it costs a lot of money to remove hedgehogs from the Uists – dead or alive. And this was at the centre of the concerns raised by the board of SNH at their meeting in Edinburgh yesterday as the conservationists had to justify the £1.2m of public money spent so far and ask for a further £1m for the next three years.

At more than £800 a hedgehog, this has had wildlife rescue centres feeling rather jealous. On that they could feed 160 hedgehogs for a week.

But it is working, right? Well, that is where there is a problem. Right from the start of the campaign to stop the killing of hedgehogs, I have been asking questions about the validity of the assumptions that the planned eradication is based upon. It was reassuring to see the SNH board taking a similar line – most notably in asking for a correction in the measure of success away from the numbers of hedgehogs removed and on to the numbers of birds successfully breeding.

That should be obvious, but everyone’s energy seems to have been directed at the rather Daily Mail-esque attitude to wildlife management: if in doubt, blame the illegal immigrant.

This is why history is so important. The very first hedgehog study I undertook, in 1986, was to look at the exact same problem on North Ronaldsay, the most northerly of the Orkney archipelago. This is still an island of natural wonders, but it no longer has some of its best known breeding birds in residence. Initially, recently imported hedgehogs were blamed, but over time it became clear that there were many other factors at play, such as farming practices and climate change. And while some hedgehogs might eat some birds’ eggs, that does not mean there is a causal link between increases in hedgehogs and decreases in breeding bird success.

Perhaps it would be better to spend some of the hundreds of thousands of pounds earmarked for hedgehog removal to revisit the original contention that they are the main problem. And if there is any money left over after that, there are some wildlife rescue hospitals that could really use some help.