Why record common species?

We heard on the radio today that the 'Common Toad' was in serious trouble. Sadly, its name suggests that it is still common, and yet the evidence points in quite a different direction. My experience in Mitcham strongly points that way. When my team surveyed the common in 1984 we did regular assessments of the breeding population of both frogs and toads. There were literally thousands of toads that spring. Sadly, a major fire some 500 metres from the main breeding pond killed a substantial part of the toad population that autumn. Crows had a magnificent feast for a long while afterwards!

Toads continued to breed in the ponds for several years but numbers declined; both within the main pond whose population had been catastrophically damaged, and elsewhere. Regrettably, nobody did regular counts in subsequent years so the impact of the fire is difficult to assess. Was this event the start of the decline or did something else happen? I cannot help feeling that the introduction of common carp and the destruction of weed beds in the ponds played an important part in the Toad's decline, but maybe there were other factors too?

The loss of such a thriving population is a tragedy but it has wider implications. I recall that in the late 1970s and early 1980s I occasionally happened across dead toads with infestations of the Calliphorid Lucilia bufonivora. That too is regarded as 'common' but I rather suspect that is no longer the case (NBN data seem to indicate a contraction but I cannot be sure). Had we had the levels of biological recording that we have today back in the 1970s, perhaps we could say a lot more about the decline of the 'Common Toad' and what has happened to Lucilia bufonivora.

This sorry tale has numerous parallels, such as the demise of the Passenger Pigeon - a once abundant bird in North America that is now extinct!

So, moving on to today's world in which there is increasing capacity to maintain all records, why don't we record common species more consistently? Only this morning a a major contributor to the Hoverfly Recording Scheme commented to me that he was unsure how much I would value repeated records of commoner hoverflies. My answer - to the contrary, we are keen to get good date runs of records. This is one reason why I now make an effort to log everything I see when out on my daily walk. Daily fluctuations are an important body of information that can be stored quite easily but cannot be reconstructed once the time has passed. We just don't know what our data might be used for in the future so the wise course is to log what one sees.

In a broader context, Brexit poses quite a serious risk to our wildlife. We really need to be on top of the issue and able to detect any changes that result from the loss of agri-environment schemes and intensification of farming practices. Making sure we record common species is an important first step - if we don't record common species we may not pick up problems in the countryside until the effects are extreme and even more difficult to reverse.

Composition of the photographic dataset of hoverfly records

A recent thread on the NFBR Facebook page drew attention to a piece of work looking at the differences between identification by 'experts' and various (relative) novice recorders. This paper generated a range of comments and stimulated me to reflect on the advent of photographic recording. I took the view that the glass is definitely half full and probably a good deal more full than the most sceptical specialists might think!

I have written previously on the importance of modern media as a way of bringing 'new blood' into biological recording and the need to embrace this new paradigm. The Hoverfly Recording Scheme has done so for many years and I think the dividends are there for all to see: we have seen a massive increase in recorder effort but have also started to recognise that this sort of effort is unsustainable without a fundamental change in the way recording schemes are organised, taxonomic guides are written and perhaps even in the way taxonomists work to describe species.

Live animal taxonomy is a challenge, and probably cannot be taken to the refinement that is possible with preserved specimens and modern molecular analysis. BUT, it is likely to be the major source of data in the future and we really need to understand its implications for data analysis and for conversion of these analyses into land management policies. This paradigm shift has been the driving influence behind my interest in photographic recording and trying to understand and quantify what is possible.

After at least eight years of data extraction from photographs, I think we are in a strong position to analyse the potential of photographic recording for hoverflies. The sheer scale of the data arriving is obvious (figure 1), but what does it really mean in terms of the spread of species recorded? Furthermore, are the numbers of records translated into something useful for land management policy? More analysis is needed to come to any firm conclusions but the data do suggest that at least for hoverflies there is potential to use photographic recording for certain analyses. The spread of species is substantial (over 150 species in 2016) and, as can be seen from Figure 2, the tail of irregularly reported species is long. At the moment I am far from clear how this compares with traditional data and will have to access the full dataset to gather a better understanding of this relationship.

Figure 1. Monthly records of hoverflies based solely on photographs extracted from Flickr, iSpot and Facebook

The spread of species is substantial (over 150 species in 2016) and, as can be seen from Figure 2, the tail of irregularly reported species is long. At the moment I am far from clear how this compares with traditional data and will have to access the full dataset to gather a better understanding of this relationship.

Figure 2. Composition of the 2016 dataset (23,790 records)

 Figure 3 (below) also illustrates how the dataset is dominated by an ever-shifting range of species throughout the year, with some obvious surprises amongst the listings of the top 20 species for each month. There must be a health warning, however, as data from traditional sources who retain specimens have yet to be analysed. My past experience has found that there are substantial differences and that one has to be clear about the source of data before drawing any conclusions about species abundance and distribution.

Figure 3. The 20 most frequently reported species each month in 2016 organised in rank order for each month.

More analysis will be provided in due course, but I hope that these three figures alone will act as a stimulus to other recording schemes to engage with photographic recorders. There is plenty of good will out there and lots of potential for growing our knowledge of Britain's wildlife. My one word of caution is that the level of interest can be overwhelming and consequently we need to change the way in which recording schemes are run. In future we will have to look far more towards a team effort rather than one or two people working on their own. That means that over time some of the contributors must be given the opportunity to play a more active role in data management and mentoring; something that the Hoverfly Recording Scheme is currently working to address.

Biological recording - is there a gulf between what recorders and recording schemes want?

Yesterday I posted a note on data extraction and management on the UK Hoverflies Facebook page. It was needed because I have reached a tipping point where I cannot keep on top of incoming data on my own. The problem has been exacerbated because Facebook seems to have developed a major glitch in which it fails to provide alerts to about 70% of posts and at times to all posts. That now means that the only way I can be sure of engaging with all posts is to constantly scroll through the page. Inevitably posts get missed.

There are two aspects to my missing posts. Firstly some people will find that their effort to engage goes unrewarded and they may get disillusioned. On the other hand, the scheme may miss out on records. Both situations are unsatisfactory, but I think the former is the most important - the point about a page linked to a scheme is that it is the outward face of the scheme and our main way of engaging, mentoring and encouraging. If we don't engage properly then we may lose that person who might ultimately go on to be a major recorder or better still a potential replacement for me or other members of the HRS team.

The ensuing engagement to my post was encouraging because there were a number of participants who were willing to look at ways of beta-testing a partial solution to the problem. My next job is to deliver that solution and I am hugely pleased to have recruited Geoff Wilkinson to help with this essential project.

Some other interesting points emerged that I think all of the recording community needs to think about. There is a strong body of opinion that favours the use of iRecord. I have no objection to this way of recording but, as I have written previously, it does have drawbacks.

The most striking drawback was drawn to my attention by somebody who e-mailed me rather than posting on the thread. In their comments (partially redacted to maintain anonymity) they said:

'I do put the very occasional photo up on BWARS and Diptera FB pages for an ID or confirmation (maybe 20 in total this year). There are times when you get a response but there are also times when you might get a few likes but no actual response at all. On the Diptera page' ...., 'responses, if they come, are often one or two word replies such as "Yes", "Calliphora", "Muscid" with little effort to explain why it may be hard to go further or what to look for'. 'My last post on Diptera was typical. I just wanted confirmation of' [a species] which I thought was a fly of interest.' The 'reply was "confirmed! Please iRecord". The reply didn't need any more than and I did put it on IRecord where it still awaits confirmation.' In a broader context it highlighted the general lack of verification, with large numbers of records in popular groups (moths and butterflies) going unverified. My correspondent went on to say 'One of the better schemes on iRecord is the ladybird scheme. They can take a few days to verify but you always get a nice email from them thanking you for your contribution.' It is a reminder to me - somehow I must look to follow their example.

Taking note of feedback

This feedback is really helpful because it reminds me why people engage on Facebook and also what they expect from iRecord.

One word answers on Facebook are not what is wanted - people want to know why a photo has been identified to that level. I have had similar complaints levelled at some of my responses on UK Hoverflies, so I am as guilty as anybody! We do need to engage and to explain why we have come to a particular conclusion. Unfortunately, that takes time, and there we hit the nub of the problem for biological recording: there are relatively few specialists who are prepared to engage, and those that do are stretched to the limits of their capacity. We must be grateful for the efforts of a relatively small minority and in that respect I must thank the team at UK Hoverflies: Ian, Joan and Judy, without whom the page would have collapsed a long while ago. I simply could not have managed on my own.

So, what is expected of iRecord? Well, the obvious thing is that people expect their records to be made use of and for them to be verified. If this does not happen, then the majority of potential recorders will probably be lost. I am very guilty in this respect with about 6,000 records awaiting verification. This is one of my jobs scheduled for the winter when (hopefully) I have a bit more time to deal with other administrative issues. Schemes that ask for recorders to place their records on iRecord really do need to verify data on a regular basis.

Why use Facebook then? Well, as I have previously noted, a very substantial proportion of Facebook group members are first and foremost photographers who want a name for their photos. Biological recording probably does not figure at first and it is only because the UK Hoverflies Group focuses on the recording aspect that this has become embedded. I dare say some contributors lose interest because of the call for data, but  I think we have to be realistic - we cannot please everybody! UK Hoverflies fits a very specific need and works because it meets the needs of the people that participate. Other pages must also meet contributor expectations but will be selective towards those who are happy with their approach.

Interactive engagement

The problem for all recording schemes is that they developed at a time when people used pen and paper, submitted record cards and if they were lucky got a brief letter of thanks in reply. Again I am as guilty as anyone for weaknesses in the response system. In this respect the internet is a great benefit as data submitted as a list by e-mail can be responded to quickly and easily!

BUT, we need to do a lot more. It is all very well submitting data, but what happens to it? Do all recorders get feedback? I fear that there are lots of recording schemes that are effectively moribund because they give no feedback. A few stalwarts do continue to engage, but if there is no evidence of activity, contributions wane. We saw this with the HRS after the publication of the first atlas; incoming data crashed as we ceased to engage, and it really only started to rise when we awoke from our slumber and started to work to produce a revised atlas.

The message is stark - it is all very well Government, NGOs and Agencies pushing for more biological recording, but the infrastructure needs to be there to meet the expectations of contributors. That is becoming a full-time job but of course is one where there is an increasing belief that data collection can be centralised without a two-way flow of information. Somehow this must change, but do we have the capacity?

Why data are important

There was an item on the BBC's 'Countryfile' on Sunday 11 September in which the findings of the latest 'State of Nature' report were discussed. I've yet to see the report, but in the past the HRS data have been used extensively in analyses of the status of Britain's wildlife.

The State of Nature Report presents disturbing but not unexpected findings – a substantial decline in wildlife across the British Isles, with a number of localised success stories for single species. On the whole, the message is very alarming (or should be). Sadly, the main agricultural contribution to the item laid the blame squarely on a rise in predator numbers but their assertions can be rapidly dismissed when one looks at the data for hoverflies:

Between 40 & 60% of hoverfly species are declining in abundance, whilst fewer than 20% are gaining in numbers/range. The declines are primarily amongst species with complicated habitat requirements, whilst gains are largely amongst species capable of dwelling in the urban environment and species introduced as a result of poor biosecurity.

If, as is asserted , the problem is predators, then by all rights with bird numbers declining hoverfly numbers should be rising! The opposite obtains: bird numbers are declining and so too are the numbers of hoverfly species that occupy the specialist niches. The conclusion is pretty obvious – something else is affecting the abundance of wildlife!

Making these connections is reliant upon sound data: the bigger the dataset is, the more robust the resulting analyses will be. Regular recording from a 'patch' or garden is a very important way of generating this robust data, but the casual contributions of all participants in the Facebook page help too.

The HRS was used for a decade or more as the test data for developing the models that inform the State of Nature report. How can we know this? Stuart Ball who is the HRS data guru was JNCC's Chief Analyst (until March this year) and did a considerable amount of the work developing current models. He always turned to the HRS data for validating models because he knew the data, understood the biology of the animals and was therefore able to sense-test the outputs.

So, when we ask for data, we are asking participants to help develop one of the datasets that might just help to change the most entrenched views about the health of Britain's wildlife.

Hoverfly identification: getting started

CHOOSING AN IDENTIFICATION GUIDE TO HOVERFLIES

If you have not got a specialist guide book, the chances are that you are either trying to match photographs to others posted on the internet, such as Steven Falk's comprehensive pages. The big drawback with this approach is that you will probably end up trying to match your photograph using colour patterns. It will work with some of the very distinctive species, but in many cases there are several species within the same genus that look very similar. Rather more unhelpfully, hoverfly patterns can vary between males and females (sexual dimorphism), between spring and summer broods (generational dimorphism) and depending on the temperatures that they developed in larval and puparial stages. Gut contents can also affect the intesity of colouration, and they may also darken with age!

The characters used to separate them are therefore often confined to structures that you will not think of without having gained a more detailed knowledge of hoverfly taxonomy. A guide book is therefore an essential part of the process: it will help you to understand how to arrive at a reliable identification and what many of the pitfalls are.

At the moment, there are two readily available guides to UK Hoverflies, both of which have strengths and weaknesses:

British Hoverflies: an illustrated identification guide

(2nd edition) 2002 by Alan E. Stubbs & Steven J. Falk (revised and updated by Ball S.G., Stubbs A.E., McLean, I.F.G, Morris, R.K.A. & Falk, S.J.. Published by the British Entomological and Natural History Society. Price £20.00 +p&p to members from the BENHS or around £30 +p&p from online retailers.

Strengths: This is the most comprehensive guide to Britain's hoverflies and contains keys to all genera. It also contains a comprehensive array of line drawings of relevant features including detailed illustrations of the genital capsules of Cheilosia and Sphaerophoria. The plates are arranged in taxonomic order and allow readers to get a general feel for some of the range and variation.

Weaknesses: This book was revised in 2002, since when about a dozen species have been added to the British list. A further revision is really needed and we have developed much of the material needed to produce a supplement. Thus, the serious student of hoverflies really needs to use this guide in conjunction with European literature.

Britain's Hoverflies: a field guide

 (2nd Edition) 2015 by Stuart G. Ball & Roger K.A. Morris. Published in the WILDGuides series by Princeton University Press. RRP £24.95 but available online for considerably less.

Strengths: This guide uses photographs throughout and is very richly illustrated with detailed shots of critical features. It was designed as a companion to Stubbs & Falk and contains illustrations of many of the features that are difficult for the novice to understand. It is the 'entry level' guide that will resolve many of the problems that the novice encounters. It also contains the most up-todate checklist for Britain's hoverflies (apart from the UK Diptera checklist on the Dipterists Forum website).

Weaknesses: This guide does not cover the entire British fauna but focusses instead on illustrating all of the genera and those species that are most likely to be encountered by the non-specialist.

In addition, it is worth drawing attention to the most useful European guide:

Hoverflies of Northwest Europe: identification keys to the Syrphidae

(2nd Edition) 2010 by Mark P van Veen. Published by KNNV Uitgeverij.

Strengths: This is the most comprehensive set of keys to the hoverflies of NW Europe and is a must have for those people who take a detailed interest in hoverflies.

Weaknesses: This guide lacks colour plates and although well-illustrated is not suitable for the novice because it depends upon a strong grasp of hoverfly morphology.

There are also several less comprehensive guide books that may be useful to those who have a very limited interest in hoverflies, but if using them be aware that many of the identifications that you may arrive at would be questionable without validation by a specialist.

SOME TIPS ON MAKING YOUR DIAGNOSIS

Many people simply try to match a photograph or a specimen in the field with a picture in the book (i.e. the way many birders work). This approach is unlikely to yield reliable records for many genera as I have noted in my introduction.

You can help to improve your analysis by checking:

1. Is the flight time right? If you decide upon an animal that flies in April but you have seen in September, the chances are that your determination is wrong!
2. Is it within geographic range? It is amazing how often people submit records for northern or upland species from southern or coastal locations. With a few noteworthy exceptions (such as Callicera rufa), these are also likely to be wrong.
3. If the guide book points towards the use of genitalia characters or greatly magnified microscopic features to separate species then the chances of a correct identification are no better than guesswork. 
4. If the animal is listed as rare or highly localised, the chances are that you have not found it. The vast majority of reliable records are for about 50 species. Start with expecting the commonest species but of course exceptions do happen very occasionally.
5. Treat your identifications with scepticism.

Over the years I have seen an awful lot of cases where  people have asserted that they were certain about their diagnosis, only to discover that they had not even reached the correct genus! Identification skills grow with time and there is no disgrace in arriving at the wrong diagnosis. Providing you then get help to see what has gone wrong, this forms the central plank of learning: we don't really learn from our successes but mistakes coupled with re-analysis embed skills.

Finally, it is probably worth reflecting that there are relatively few people who make the transition to photographic/live animal identification from the use of a microscope and preserved specimens. They will often be far more cautious about making a firm diagnosis of live animals because they have seen a lot more of the range and variation and are aware of many of the pitfalls that can catch out the unwary.