As I write I’m listening to the Radio 4 series AntiSocial with Adam Fleming and this week the topic is the economic and social cost of nature conservation. One of the topics being discussed is the so-called ‘bat tunnel’ being built through an area of ancient woodland in Buckinghamshire. The cost has been estimated at £100 million and, according to The Times, this amounts to £300,000 per bat protected. That’s clearly a lot of money to protect bats, but is it an accurate reflection of reality? The answer is no, and here’s why.

Let’s put aside the fact that the ‘bat tunnel’ will protect a lot of other wildlife associated with this area of ancient woodland, including other bat species and a range of additional mammals, birds and insects. Let’s also ignore the fact that the cost of the tunnel is so high because of decisions made by HS2 that have nothing to do with bats, such as making it wider to accommodate local train services. Let’s instead just focus on the type of bat that’s being specifically discussed, Bechstein’s bat. It is indeed a rare bat in Britain, known from just six breeding populations, all associated with ancient woodland (itself a rare habitat type in this country).

The population that the ‘bat tunnel’ protects is estimated to be 300 individuals – that’s where the figure of £300,000 per bat comes from, i.e. £100 million divided by 300 (actually £333,333 per bat, but let’s not quibble about a few tens of thousands of pounds when HS2 is going to cost tens of billions).

Anyone in possession of both a sense of proportion and some basic maths can see that such a calculation is nonsense. The tunnel will be in place for many decades, potentially hundreds of years. Over time bats will die and other bats will be born. Some will stay in the area and others will migrate away and (hopefully) found other populations, or at least add to the genetic diversity and growth of one of the other existing populations. Calculating the cost-per-bat on this basis is both impossible and nonsensical. But then making that initial calculation was also a pointless exercise. The only reason to do it was to generate publicity and clicks for a newspaper that ought to know better.

As I’ve previously discussed, the railway system of Britain and the rest of Europe has both a negative and a positive impact on biodiversity across the region, and understanding those impacts is important. Thoughtless, politically-motivated journalism such as The Times is promoting is not helpful.

(Before anyone asks, the photograph accompanying this post does NOT show the ‘bat tunnel’! It’s a tunnel in Tenerife, part of the network of water conduits that were built in the past and now provide homes for many of the resident bats)