Thursday, 20 March 2014
Validating records and the issue of killing invertebrates
The question of whether or not it is acceptable to kill insects in the process of biological recording is one that polarises views. On the one hand there are some who believe that all records should be backed up by a pinned specimen; on the other there are those who believe that nothing should be killed. Some people argue that insects deaths resulting from impacts with cars is accidental and therefore acceptable; others argue that roadkill contributes to the overall loss of biodiversity and should be minimised as far as possible. I fall somewhere in the middle of these views. It therefore seems to me that there is merit in exploring the various issues in a bit more detail.
To start with, it is worth thinking about what biological records are used for, and why so much time, effort and money has been invested in such initiatives as the National Biodiversity Network, the Biological Records Centre at Wallingford and the plethora of local records centres and recording initiatives. Not to mention the armies of volunteers who undertake everything from the hugely important Wetland Bird Surveys and Butterfly Monitoring schemes, to national recording schemes, atlas projects and bioblitzes.
Robust, reliable and up-to-date information is an essential part of nature conservation. It underpins the site designations that protect International, national and local wildlife sites. The trends that can be discerned inform the development of red lists and protected species legislation. And, of course, trends also influence political thinking. If the underpinning data are poor, the subsequent analysis will be weak and vulnerable to attack from those whose interests are threatened by changing legislation and policy; be that development of marginal land or application of a new form of pesticide. So, there is an onus on those who compile the data to make them as robust as possible. In the case of the Hoverfly Recording Scheme, the buck stops with Stuart Ball and with me. As I tend to do the taxonomic validation of records, I thought I would set out my thoughts on the issue and explain how go about making sure the data are as robust as realistically possible.
The one reliable way to be absolutely sure is to only accept records generated by oneself or specimens verified oneself. Such an approach is impractical, but I am aware of recording scheme organisers who have taken such a view. Following the latter course means that the dataset is extremely sparse and probably not sufficiently robust to make statements about the status of species, either geographically or in terms of abundance and responses to change. This approach is not viable for the HRS and therefore we must accept that a small proportion of the data we absorb are incorrectly identified. As I won't claim to be perfect myself I think I must simply do my best to establish sufficient rigour to give confidence in the dataset (the man who thinks he does not make mistakes is either arrogant or too fastidious to be effective), I therefore use various tests to see whether the submitted data are accurate.
When we accept records from recorders, we can make an assessment of their approach, based on the composition of the list that is submitted. There are obvious clues. For example, there is a well-known insect ID guidebook that has a very glaring hoverfly identification error in it. When I see records of that species in the dataset an alarm bell rings and although we absorb the records into the database they are flagged as questionable ID - which means the records are never used in analysis. I hope that error remains in subsequent editions as it is a fantastic marker for one line of recording! It also means that I have a knowledge of the recorder and can be vigilant for future records. These data also show how incomplete guidebooks can have a potentially damaging impact on datasets.
The second clue is whether difficult taxa are included in the list, and which parts of those assemblages (e.g. Cheilosia, Sphaerophoria etc) - when I see the gender of certain species included in the data I know the data has been submitted by somebody who matches specimens to pictures and does not read and respond to the text. The chances are, therefore, that they have not used the keys and therefore there can be no certainty about the validity of the records. Here I flag the easy species as accepted and flag the others as questionable. In this case, the lesson is that even if people have the right text books, a proportion will not use them properly and will not match the standards that the recording scheme organiser has to adhere to.
The third clue is whether or not there has been validation - either a voucher specimen or a photo. If a voucher specimen is available,I start to feel that the recorder is making an attempt to use the very necessary processes of cross-checking that are needed to deliver reliable data. As long as there is nothing in the really difficult taxa, then I may well accept the full dataset. I might want to see specimens/photos for difficult taxa i.e. those we would class difficulty grades 4 & 5 in our system of validation (1 = generally safe to accept, 4-5 represent taxa that require very diligent validation). Once I have seen specimens and have a feel for the competence of the recorder I am more likely to accept their records immediately. That is, assuming their IDs are correct. Sometimes I get photos to support records and find that the genus is wrong and sometimes even the family!
Now, moving on to the value of this process. It means that the majority of records do get accepted, but that the dataset is heavily skewed towards commoner and more readily identifiable species. This presents us with a problem because the scheme has a very strong link to nature conservation. For example, we use its data to evaluate the conservation status of hoverflies (which is listed in our book). We can only do this by having access to data covering the full range of taxa - a sub-set will not be as valuable to conservation and it could mean that an immensely useful conservation tool is blunted. That would be a real problem I think.
In addition, datasets that do not include all taxa also skew the robustness of their use in trend analysis and its application to developing environmental and policy issues. Complexity of identification is not a valid analogue for relative abundance. Some very common species of hoverflies are fiendishly difficult to identify without strong magnification and examination of characters such as the male terminalia. For example, as a general rule, the genus Sphaerophoria cannot be identified beyond generic level without detailed examination and reference to comparative material.
So, I believe the case is well-made for rigorous identification and validation processes to make sure that whatever data are available are reliable. I think we can be reasonably assured that the majority of the HRS data meet this criterion, but we can never be 100% certain. Whatever the actual situation is, I feel I can say that the data are screened to the best level that can be achieved with the resources we have available to us (i.e. unfunded and using experience of more than 70 years).
Moving on to the issue of road kill. There are two aspects to this. One is that, if a car is used to make visits to the countryside, it is almost certain that the drive to and from the site will involve the death of a number of invertebrates. The numbers today are doubtless much lower than they were 30 years ago, but they cannot be dismissed as irrelevant. Consequently, it is possible to compare the careful selection of a sample of specimens with the indiscriminate impacts of driving the car. Both lead to the death of a number of invertebrates.
The collection of specimens is a very deliberate decision to capture and kill animals. As such it can be judged because the decision has been made to kill; it is not an incidental result of a more legitimate process that can be justified for personal reasons - or is it?
In the case of animals killed by cars the question arises as to whether these deaths are accidental by-products of a legitimate activity. Those advocates who argue that they are not deliberately killed overlook the fact that a clear decision has been made to drive the car. Making that decision means that we also make the decision to knowingly kill insects (everybody has experienced the thud of an insect hitting the windscreen, followed by the trail of ooze that paints the screen with the animal's remains).
An example that ought to resonate with readers is the problem of recording bumblebees. I stopped recording bumblebees a long while ago because I cannot do them without killing them. But, we might all help if we picked up these roadkill and submit them to a scheme (I have long held that walking roadsides and collecting bumblees killed by cars might be a good way of looking at the effects of roads on bumblebee populations). The point of course is that without valid data, bumblebee conservation will lack the critical tool to influence policy and raise the profile of bumblebee conservation.
Looking at these two scenarios, it seems to me that it is not possible to make a value judgment about the acceptability of killing specimens without also asking whether it is acceptable to drive a known killing machine and regard the deaths of countless insects as an acceptable legitimate by-product. If specimens are killed and the data that result are used for a valid purpose, including wildlife conservation, it is surely no worse than driving your car to go to work, for a country visit or to shop in the out of town hypermarket? And, it should also be remembered that the lorry that delivers food to the shop will also have killed insects.
It therefore seems to me that we cannot really absolve ourselves from the processes that kill insects. There is a paradox that involves value judgments about the differences between the two activities. Cars lead to betterment of our minds, bodies and happiness above whereas the production of the highest quality evidence that MIGHT be useful in changing land management policies.
There are two ways of addressing this issue. Firstly, if convinced that there is a need for taxonomically rigorous data, we can make appropriate collections of invertebrates with the expressed intentions of contributing rigorously assembled data to a scheme that does set out to help influence policy. Those who remain uncomfortable with deliberate killing of insects can still do their best to provide details of what they see, at a level of validation that is consistent with their value judgments. There is no compunction to take specimens, especially as for most people the primary objective of a countryside visit is a nice day out and improvement of the mind and body. I would argue that everybody, however, has a responsibility to make sure that the indiscriminate deaths of insects are minimised or or are ameliorated by improving the body of information that might help to save wildlife.
I would therefore argue that where the car is used to visit the countryside, one should also participate in whichever recording schemes fit our interests in the natural environment. It might be as a birder - if so, perhaps contributing to WeBs counts, breeding bird surveys or other initiatives. If so, added value might be the incidental (accurate) records of other taxa observed in the course of the day out. Alternatively, it might be conducting butterfly transects and noting the occasional beetle, hoverfly etc. Or, it might be compiling a comprehensive photographic record of the insects visiting a particular site. Critically, unwillingness to kill animals indicates a love for the natural world, and what better way to love it than to make a contribution to the science that might help to conserve it!
So, with that I will sign off by emphasising that everybody can make a valid contribution to conservation by making their trips into the natural world count for as much as possible. If datasets are strong, then the evidence placed before politicians becomes more powerful. That in turn gives the natural world a fighting chance, providing it has technically competent advocates who can present a compelling and evidence-based argument. We therefore need the taxonomically rigorous recorder as much as we do those who prefer to avoid collecting.
The natural world is there to be valued. It enriches lives and is the life-support system for the planet. Our responsibility is to therefore to protect it, and to provide it with the defence mechanisms it needs to survive the ravages of man's worst excesses.