Species status depends upon accurate information

Following up on a thread on UK Hoverflies concerning wildlife tourism, I thought I ought to go back to the status review of hoverflies to illustrate the state of knowledge difference between hoverflies and butterflies.

With butterflies, we see a continual growth in the numbers of species creeping towards the red lists.That creep exemplifies the problem of a lot of Britain's wildlife: habitat is being lost or it is changing as a result of atmospheric nitrification, lack of management or inappropriate management, or basic loss of habitat.

In the case of hoverflies, however, the reviews point in the other direction with species being knocked off the lists on a fairly regular basis. This is because our state of knowledge is slowly improving and it turns out that we got the status wrong in the first instance. As with all things, early versions are often troubled by lack of data. This is illustrated by the changes in the conservation statuses currently used and those from the previous generation of reviews.

Figure 1. Conservation statuses of hoverflies from three generations of status reviews. Note that the system for evaluating red-list statuses has changed but the one for determining 'Nationally Scarce' has not.

The more data that we have, the better chance we have of identifying robust and meaningful conservation statuses. If we lack the data then the hand of those who wish to undermine the importance of less well-known taxa is strengthened! You can see the riducule coming up in the Public Hearing:

..... 'and how many people actually look for this 1cm long fly?' 'You say maybe 20!' 'That suggests to me that the fly is not rare, but is overlooked and of little consequence'. 'Your Honour, I submit that this evidence is false evidence because it is incomplete'.

It is an issue that Stuart and I have grappled with for a lot of our working lives. We have long argued that the problem for invertebrate conservation is that it is a Cinderella subject. So few people take the time to develop real skills and therefore the volume of information available is small. Those who wish to destroy important invertebrate sites can rubbish the conservation argument with ease, and the press can destroy it with a few choice headlines - e.g. 

100 new jobs put at risk by tiny fly!

When we prepared the status review for hoverflies we built in some resilience by looking at the levels of recorder effort and adjusting the statuses to take this into account. Our approach will hopefully mean that the statuses will remain largely stable in coming years, but we must expect there to be some movement in lesser-known species. But we still need more people to tackle the difficult groups that require specimens and microscopy. Unless we encourage the development of detailed skills and the greater use of microscopy, much of invertebrate conservation will continue to be a losing battle and we will be unable to reliably track the fates of the more specialist species.