Getting to grips with hoverfly identification

Learning to identify any group of organisms is a challenge that at some stages can seem to be insurmountable. I'm not sure there is a 'right' or 'wrong' way as everybody learns in different ways. What works for some may not work for others; but there are some simple tips that may help.

• Identification is dependent upon recognition of features that are constant within the species concerned. In the case of hoverflies it needs to be borne in mind that they can be hugely variable in size and colouration in response to temperatures during larval and pupal development as well as sexual dimorphism and brood dimorphism. I know Alan Stubbs spends goodly periods of time checking a range of characters for consistent features when he develops keys - and the message that comes out is that relatively few are reliably the same.

• This complication means that whilst illustrations are useful, they only form part of the process. Understanding how to recognise the different Tribes and genera is crucial. This is where access to complete keys is very helpful - the keys will provide a series of markers that help to direct observations. It is also important to bear in mind that keys work on the process of elimination; so, the earlier they appear in the key the more genera or species may have this feature in common. In addition, once two different pathways are followed, it is quite possible that a very similar character may be used to identify two very different species. Understanding these relationships is important. This is one critical reason why we have been resistant to producing a guide to all hovers without detailed keys. The current WILDGuide is a best effort to introduce the family but cannot be regarded as perfect. The 'key' to tribes is critical and really should be used in the first instance; at least until you have seen most of them or recognise obvious ones. If in doubt, go back to first principles.

• Working with keys does not mean that one should not use the photographs/illustrations to help arrive at a conclusion, but the crucial point is not to force the identity to fit the picture. There are several obvious areas where this can (and does happen): hive-bee mimics and bumblebee mimics often cause problems. It is important to recognise that whilst the markings on the abdomens of hoverflies often appear to be distinct, they are frequently no guide to the species. Confusion within Syrphus is an obvious example where the critical characters are microscopic. And, I have regularly been asked 'so why is this a Syrphus' - answer - you need to examine the upper surface of the squamae to be sure - but these are not visible on photographs or on specimens with the wings folded.

• If one sets aside the keys and simply tries to match specimens to photographs there will always be challenges because the introductory guides cannot ever provide all the necessary corroborative information (bear in mind that Stubbs & Falk is well over 500 pages of keys and descriptive text plus illustrations of male terminalia). It may not always be possible to reach a firm conclusion for a substantial sub-sample without taking specimens and keying through using a microscope and detailed monographs. So, we must work with what we have to hand, and use a certain level of judgment. Corroborating evidence can be helpful but is not foolproof - e.g., time of year, location, habitat, size (difficult to be sure with photos). It is distressing but not surprising that the NBN often has maps with dots well out of range - those recorders ought to have challenged their own IDs if they had read the distribution information.

• We have tried to illustrate critical features in the WILDGuide, and where these are shown they should help to separate species involved. This is not perfect, however, and making judgments is often dependent upon experience. So, the novice should not be disappointed by problems in making early identifications: until you have a mental picture of critical features the process will always be slow and frustrating. But, it does get easier.

• In my experience the majority of 'novices' actually come across quite a limited range of species. Most are 'common': Eristalis, Syrphus, Helophilus, Volucella form the majority of the assemblage. Tricky genera such as Cheilosia, Pipiza and Platycheirus are rarely seen over and above some very obvious animals such as C. illustrata, C. variabilis and P. albimanus. Recognising the genera is a good first base. Once you can readily say that this is an x or y, then you can move on to separate the species.

• One way of getting to know what the animals themselves look like is to make a habit of working through the guide and reading descriptions and species accounts so that you have a feel for range and variation. As a small boy I spent hours engrossed in whichever book caught my attention. I had a pretty good idea what I was looking for even without seeing the animals themselves. What is more, I knew what to look for! So, as an example, I recall reading about puss moth eggs and that they were found in pairs on the underside of poplar leaves. At the right time of year I looked for the eggs and the second leaf I turned over yielded a pair of beautiful little eggs - I was hooked! I shared this haul with my pal John Stevens - each of us rearing a wonderful caterpillar and enjoyed watching them make their cocoon. A beautiful fluffy white moth emerged the following year!

• Identification is a process of elimination. It is as important to understand what the subject matter is not, as much as what it is. So, one can say - I know with confidence that this is not an x or y - and hence the numbers of possibilities is reduced to those that actually fit the what it might be section. The critical markers generated by previous experience are part of this process. Remember: getting identifications right first time does not necessarily mean you have learned anything - you learn as much from getting it wrong and of course when this happens you actually have a mental hook to use to help in future. I use this process all the time. I cannot remember everything, but if I come across certain cues, I am reminded of past mistakes (we all make them).

• Those entomologists who maintain a collection have the advantage of referring back to voucher specimens, but you can do something similar with photos - creating albums in taxonomic order. These may help - although you might also usefully look at Steve Falk's excellent Flickr library.

Following these processes, I think the best way is to think in the following manner:

1. Can we establish the Tribe to which the specimen belongs?

2. If so, aim to the relevant part of the book. In many tribes the animals are very different, and so you may find that there are several very similar animals involved.

3. For many of the Tribes, a simple key to genera is provided - follow this and you should get to the genus.

4. When at the generic level, individual photos should help, but there are also supplementary photos that should help - use these where they are available.

5. If you come to a conclusion about a species, check the descriptive information and note whether there are similar species. If similar species are listed, check against these before making a judgment.

6. If working from a photo - post it on a suitable platform (UK Hoverflies Facebook group, iSpot, Wild About Britain) and see what others think.

7. Don't be put off by mistakes - simply look upon them as a learning experience and have another go with other examples. Remember, we all start at the beginning and progress; and even the 'experts' make mistakes!

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.

Spring is nearly here

This last week's storms have rather taken attention away from what ought to be time of renewed hope. The yellow crocuses are in full bloom, as are the pale purple early spring crocus and snowdrops. In the urban garden there is probably more for hoverflies to find nectar and pollen sources than in the countryside. I rarely see anything at hazel catkins, but then I probably don't spend enough time looking!

What really struck me, however, was how the spring garden has changed in the last 40 years. When I was growing up in London in the 1960s and '70s our garden was often filled with the excited chatter of a flock of house sparrows. Those same house sparrows used to descend on the crocuses and tear them to pieces, so one of the first winter jobs for my mother was to create a latticework of cotton over the flowers to keep the marauding birds at bay. I cannot remember when we last had to do this in my mother's London garden. Today, the garden is silent - the sparrows are gone.

The house sparrow is in many ways just part of the story. In winter months we were also treated to the amazing spectacle of millions of starlings streaming out of London towards their roosting grounds in the hawthorn copses of Mitcham Common. They used to turn the sky almost black just before dusk. The hawthorn thickets were often white with starling droppings. Again, the spectacle is gone, but the starlings' legacy lives on because the most favoured woodland roosts have a very different ground cover - each former tree (now largely dead and overtopped by oaks) is represented by a ring of nettles and elderberry. It is an important reminder just how important birds can be in nutrient cycling and also how environments can be subtly changed by a passing phase. This sort of impact is worth remembering because it can help in interpreting the evolution of the landscape.

What we have in place of the sparrows and starlings is a huge flock of ring-necked parakeets that roost in a poplar plantation on Mitcham Common. There can be several thousand on a good night. I would much prefer the starlings and sparrows as these noisy replacements fill the air with squawking that can be really quite a distraction.

The carrion crows of London now descend on the common too; they never did this when I was a boy. On the one occasion I made an effort to count them I noted nearly 600 birds assembling in the poplars along the railway line adjacent to the Croydon Road. The crows then descend upon the Golf course where I assume they spend the night. It is a very different but still an amazing spectacle. Quite what it tells us about the ways in which the ecology of London is changing I am not sure. Crows used to breed in the big poplars and their old nests were subsequently used by kestrels. The poplar trees were blown over in old age and have yet to be fully replaced by the younger plantations. The kestrels have gone too. So have skylarks, reed buntings and stonechats; and linnets, goldfinches, greenfinches and bullfinches are considerably rarer. We do, however, have a magnificent flock of Canada geese that are changing the ecology of the Severn Islands Pond and the surrounding acid grasslands. There is also a delightful pair of Egyptian geese that has successfully bred.

So, I hear you say 'what does this have to do with hoverflies?' Perhaps nothing; but then again, had I not gone into the garden to look for hoverflies I might not have recalled the mischievous chatter of the house sparrows and the changes that have happened in the passing of just 40 years! In many ways, this is a metaphor for all those other changes that have happened, that perhaps the less observant or interested do not notice.

Offsetting Ancient Woodland

Looking at the pronouncements on possible ratios of replacement trees to original trees, I wonder if the Government has seriously considered the areas of land required to offset loss of ancient woodland? Using some basic calculations, it seems to me that they are going to have to require some major areas of the countryside to be allocated to tree planting if they are serious about a 100:1 replacement ratio.

I have just done some 'back of a fag packet calculations (thankfully I gave up 10 years ago, so I have to use scrap paper but I doubt that makes much difference to the science!) and the following figures come up:

1. In traditional coppice with standards, tree density is likely to be anywhere between 30 and 100 crowns per hectare. That, I suspect refers solely to the 'standards' and thus the question must be whether additional provision needs to be made for the coppice stools?

2. Working on a density of 65 crowns per hectare as a median, that suggests that the Government is proposing a compensation ratio of 6.5 ha for every 1 lost to development. This is a ratio that far exceeds any so far for displacing migratory waterfowl.

3. If the pastiche is to replicate ancient woodland, then there also needs to be management to create the mix of coppice stools and standards. What needs to be borne in mind from an ecological perspective is that the coppice stools form a substantial part of the ecological value. This is largely underground and comprises the decaying timber that supports many fungi and the animals whose larvae feed on the fungi and bacterial soup that results.

4. It follows that the offset will require intensive management, unless of course we are simply looking at replacing an ancient woodland with a poor quality plantation. If so, there is even more to go on in terms of ecological loss because the relative importance of plantations and semi-natural habitats ought to be relatively easily demonstrated.

There is plenty of sound ecology to challenge the proposals, but perhaps the more important issue is economics? Is it really worth trashing an ancient woodland if the developer has the cost of buying anything between 3 and 10 ha to replace each hectare lost, and then has to pay for intensive management for sufficient time to create anything approaching pastiche? Someone better than me can do the economics, but it seems to me that the likely cost of creating the offset will at least mirror the cost of the ancient woodland and may indeed greatly outstrip it because woodland is relatively cheap and even low grade arable is phenomenally expensive, without adding on the cost of long-term silviculture.

Biodiversity Offsets

Recent announcements about the coalition Government's proposals for biodiversity offsetting raise some very serious questions about the degree to which policy is based on sound science. In 2005 a team of English Nature specialists investigated the issue of offsetting from the perspective of how long it might take replacement habitat to reach a condition commensurate with established semi-natural habitats. The evidence was disturbing because it highlighted a series of fundamental problems:

·         Established habitats are very largely the product of management that existed prior to deep ploughing and modern herbicides, pesticides and fertilisers. These modern practices mean that it is not possible to look at arable reversion from the same perspective as times when agriculture was less intensive.

·         All of the evidence pointed to very long timeframes for the creation of habitat that is any way analogous to existing semi-natural habitats. Apart from some wetlands, the timescales run into many decades or hundreds of years, and ancient habitats look to be extremely unlikely to be replicated. For example the plants and animals inhabiting a secondary woodland younger than 400 years are rarely, if ever, as rich as those in ancient woodlands.

·         The most critical factors involve a combination of soil chemistry, mycology, lithology and hydrology, and we know precious little about the role of bacteria in determining conditions. Soils that have been recently ploughed and fertilised with petrochemical-based fertilisers bear little resemblance to the chemical and biological conditions that existed prior to WW2, let alone those of the 17th Century, which marks the point at which woodlands start to be considered to be 'ancient'.

A paper published by this team in 2006[1] provides the foundation for the scientific debate about the likely efficacy of biodiversity offsets. Yet this, and associated evidence, seems to have been ignored, if pronouncements concerning ancient woodlands are genuinely the Government position. Suggestions that the replacement of an ancient woodland with 100 trees for each ancient tree lost is environmentally sound need to be tested scientifically. Is the Government thinking of the environment in a visual or an ecological sense? I think it must be assumed that this is a landscape rather than an ecological judgement because I cannot see how the Government's conservation advisers could conclude that there would be anything other than biodiversity loss from the destruction of ancient woodlands.

I have spent a substantial amount of time studying the insects of the British Isles and have visited a great many sites, from Shetland to Cornwall and Kent, both ancient and modern. In many cases one barely gets past the entrance before it is apparent that the site is going to be of interest or is going to be pretty mundane. One gets the feeling from the ground flora, the canopy structure (in woodlands) and the overall layout of the site. The insects are pretty telling too. Long-established sites invariably prove to be more interesting and there are good reasons for this.

At one time the countryside was far less regimented and there were uses for virtually everything. Coppiced trees provided small timber for tools, fencing or other utensils, and for firewood and charcoal. Standard trees provided structural timber and planking, whilst certain trees were deliberately pollarded to provide timbers of particular shapes for construction or shipbuilding. Grassland might have been rotated to lie fallow to improve soil productivity; elsewhere it would have provided grazing or hay. The vocabulary of the countryside reflects this diversity of use with terms such as coppice (copse), meadow and pasture forming place names. This mixed environment in which habitat was closely juxtaposed allowed plants and animals to disperse relatively readily. Today, such habitat is isolated in little pockets that we call nature reserves or protected sites.

Site protection has arisen because a part of society actually values wild places. This is particularly so for ancient woodlands, which form a central part of the countryside, both for their landscape and wildlife value. The landscape attributes are obvious, but the wildlife is rarely recognised. Much of the important wildlife (in terms of rarity and specialness) is small and relatively inconspicuous. Few visitors to the countryside other than the most ardent specialists would delight in the sight of a Duke of Burgundy Fritillary Butterfly or perhaps a Musk Beetle. It therefore follows that relatively few would miss their passing. But, many older people lament the loss of fields full of orchids or comment that butterflies seem to be much scarcer these days. In the case of my passion, numerous associates comment on the decline in insect activity at hogweed. Only today one of these friends commented that the hogweed fauna of Shropshire seemed to have declined substantially in recent years. One wonders why?

Once the basic landscape matrix has been lost, wildlife cannot move as freely. If a special site is destroyed, the special plants and animals don't just move - they die! Once they are gone, the overall numbers available to set seed, disperse spores or lay eggs to create a new generation also decline. This is why there has been an ongoing effort to arrest biodiversity loss. The first target date was 2000. That date was ambitious and the target was not achieved. A new target was set for 2010 and it too was missed. The current target is 2020 and yet in the midst of this decline, the Government determines that further ancient sites should be destroyed and replaced with pastiche. After all, nobody will notice providing the countryside has trees to create visual spectacles! If one waits for 100 years for the site to attain the characteristics needed by the plants and animals displaced when the ancient woodland was cleared, where will the colonists come from? They disappeared when the wood was bulldozed!

This saddens me greatly because we must brace ourselves for a further round of accelerated wildlife loss. There are already many parts of the country that are to all intents and purposes ecological deserts. The fens of south Lincolnshire immediately spring to mind, but there are others such as the Vale of York, the southern uplands of Scotland, much of Radnorshire and many parts of the uplands of northern England where the landscape may be spectacular but is dominated by sheepwalks! And then there are the urban habitats where the gardens are turned into concrete and wooden shrines to the motor car or the barbecue!

So, do biodiversity offsets have a place in the provisions for wildlife? The answer has to be yes, where there is small-scale cumulative loss of countryside matrix. But, there is surely a line to be drawn before more special sites are destroyed in the name of advancing the economy? If not, then nothing must be sacrosanct and we must start to consider clearing ancient villages to release land for new housing so that we don't lose the remaining agricultural land that we will need to feed coming generations - we cannot surely be anticipating using this to plant trees on!

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[1] Morris, R.K.A., Alonso, I., Kirby, K.J. & Jefferson, R., 2006. The creation of compensatory habitat - can it secure sustainable development? Journal for Nature Conservation. 14(2): 106-116.

Data from Photographs

In the course of the next six months I intend to prepare a preliminary analysis of the data gathered from websites over the last five years and to publish somewhere in the peer-reviewed literature. Odd snippets have emerged already but so far (in my article in British Wildlife and also a paper in the journal of the BENHS) but  I have not undertaken a comprehensive review. I'm not aware of any other such analyses but if anybody has come across them then do let me know.

In the past two month there has been quite a recognisable surge in data via photographers as a result of the establishment of the UK Hoverflies Facebook page. I have been amazed by its impact. There is now quite a recognisable community of photographic recorders and a steady stream of new records comes from this source. Other sources such as Ispot and Flickr remain very important, however. The ability of participants in Flickr to communicate with one another has meant that several Flickr users have now become very active recorders of hoverflies. This is fantastic.

The following graphs represent early analysis of the data but present a flavour of the nature of what is emerging from all photographic sources. So far, around 15,500 records have been assembled.

Figure 1. Numbers of identified photographs over the period 2002 to 2013. Data for 2013 are incomplete because the graph represents data to 12 October 2013. It can be expected that data for 2013 will increase substantially by the end of the year and will increase further over coming years.

The data tell an important story about the level of photographic activity. Relatively few people regularly photograph hoverflies. Eleven people (0.5% of recorders) have contributed around 20% (3,120) of all records and ~50% (7,600) of the records have been contributed by 100 people (4.2% of recorders). The data also tell us a great deal more and can be interrogated in many ways. We can say with some confidence that there is no specific tipping point where photographic recording came into its own. There has been a continuing and consistent growth in recording as shown in Figure 1. However, the development of ISpot has certainly helped (since 2009). The data collected since this point are arguably robust enough to show how this type of recording might be used to develop citizen science monitoring programmes. As a taster, Figure 2 shows how photographic activity mirrors levels of insect abundance in response to weather patterns.

Figure 2. The percentage of yearly records occurring each month over the period 2009 to 2013. This illustrates how periods of unfavourable weather affects recording effort and possibly also hoverfly abundance. For example, low numbers in July 2013 reflect a major decline in photographs posted during a period of extremely hot weather.

These notes should be seen as a highly preliminary analysis and should not be used as firm results. More work is required to make sure that duplication has been weeded out and to make sure that 2013 has been properly documented. However, they do indicate the potential of photographic data, whilst also highlighting the possible level of effort required to extract such data.

Local groups

I was in contact with a Flickr user yesterday who asked me whether I had thought of setting up a local group to improve coverage of a poorly recorded area. At the time I thought that I was probably doing as much as I could (the HRS, DF Field meetings, Training events and of course this group), but is there more that could be done?

Well, realistically, I doubt I can take on much more, but we do know that local groups can be helpful. For example Northamptonshire was an empty space on the maps until John Showers got interested and organised a local group. His group is now pretty active and Northants is now one of the better-recorded areas. So, is there scope for doing the same elsewhere? There are plenty of possibilities - what is needed is local interest.

Are there potential leaders out there who would like to stimulate improved levels of recording? Even well-recorded areas will need a new generation of recorders as our stalwarts are aging and not being replaced. Does anybody have any thoughts? There are active groups in Northants and a newly created group in Devon, together with an active group based around Preston Montford.

For those who want to get a feel for weak areas of recording, the maps on the HRS website are useful. http://www.hoverfly.org.uk/portal.php?id=2&scol=HFF0000&bkgrd=1&ecol=H0000FF&page=4

Obvious challenges are parts of Wiltshire, Buckinghamshire, South Lincs and the Fens, North Lincolnshire, Herefordshire, North and East Yorkshire, Northumbria and many parts of Scotland. Why is this? Well, I think one reason is maps tend to show where people like to go – and who wants to wander the barren wastes of the Fens? I have done this for about 10 years on and off – and it can be very boring. So at least in part, maps show where there is good habitat. But even in these areas there are little gems that the outside recorder does not know about.

It is also very noticeable that the bulk of recorders come from southern counties – why is this? Bearing in mind the historic legacy of the Workers Educational Institutes and numerous microscopy societies that abounded 100 years ago, surely this is not an area that is free of interest in wildlife recording?

What is needed is a network of 'shakers and movers'. They don't have to be experts but an ability to organise and motivate is really important. I have written on the subject from time-to-time and it does worry me that the most obvious group does not seem to be coming forward. These are recent graduates looking for a way of getting experience and making themselves stand above competitors for jobs. When I was in my formative years the local NHS was crammed full of young enthusiasts - me, Graham Collins, Jim Porter and Steve Church, Roger Hawkins, David Baldock, and led by inspirational people such as Ken Evans. That same society has no young members and I gather that meetings rarely comprise more than 3 people!

Food for thought?