Friday, 23 September 2016

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?

Tuesday, 13 September 2016

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.

Monday, 12 September 2016

Hoverfly identification: getting started


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 ages!

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.


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 from photographic/live animal identification to using the 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.

Saturday, 20 August 2016

Making sense of data for July & August 2016

Further to my last post, I had a look at the same dataset (i.e. 01 July to 13 August) to see how the data for the same period in each of the previous three years compares with 2016.

A total of 126 'species' were recorded over this period between 2013 and 2016:

Number of species
Number of records

Making something of this is not straightforward as the yearly figures are so different. The simplest way of expressing the data is as a proportion of the total records. For the purposes of this quick analasys it will have to suffice although there more complicated statistics might be applied. More detailed investigation will have to wait for the time when we have a much bigger dataset covering many more years.

Top 50 species in 2016

A relatively small proportion of species make up the bulk of the records so when they are organised in rank order, largest to smallest, for 2016, one is well into the tail of occasional records by the time one gets to the 50th most abundant species (Figure 1).

Figure 1. The 50 most frequently recorded hoverflies fro, 01 July to 13 August organised by rank order for 2016 as a % of the total records for the recording period that year. Orange highlights the highest year proportion and blue the lowest.
Taking the top 50 in 2016 as a cut-off point, I then looked at which year was the best for each species, and which year the least productive and then converted each into a tabulation of larval biology to generate Figures 3 & 4. (Note: I lumped Myathropa florea into the wetland guild because they often breed in locations that might strictly be considered to be wet features rather than dead wood habitat).

Figure 2. Best representation in each year according to larval biology

Figure 3. Poorest representation in each year according to larval biology


What do the data tell us?

At first glance, one might say 'not much', but there are subtle and possibly important differences:

  • Wetland and aphidophagous species are the two guilds that dominate the most frequently recorded species list. It seems that in years when wetland species do well, aphidophages fare less well, proportionately. Of course, it may simply be that when wetland species numbers rise, the ranking of other species is diluted and they apparently fare less well. A more comprehensive statistical analysis is probably needed to investigate this, together, perhaps, with a much bigger dataset.
  • 2014 was a particularly good year for species associated with Hymenoptera; either as scavengers and parsaitoids in social wasp and bee nests, or associated with ant attended root aphids (if larval ecology conforms to current thinking).
  • The data used in this analysis cover the later stages of the hoverfly season, and certain guilds are probably under-represented because they emerge earlier in the year. This is particularly the case for saproxylic (dead wood) species. More detailed analysis will be possible when the full 2016 dataset has been assembled.
  • There has been a greater than threefold increase in the volumes of data assembled using photographic recording, and as such the dataset is starting to be sufficiently big to be a powerful tool in its own right. Good coverage of species is achieved, but it seems likely that there is under-representation of some guilds, especially plant feeders within the genus Cheilosia.
Some bigger questions emerge from this rather crude analysis:
  1.  To what extent are differences in the proportions of hoverflies recorded in individual year  a reflection of environmental factors within in that year?
  2. Conversely, to what extent does the weather (or other environmental factors) in preceding years impact upon numbers recorded in any given year?
At the moment neither question can be answered with certainty. Nevertheless, most of the commonest hoverflies are species that have several broods each year. It therefore seems likely that the weather in preceding months rather than years will play a dominant role in governing individual species' abundance. We know that this happens in species such as Rhingia campestris and it seems equally likely that the same will obtain for both wetland and aphidophagous species.

Hoverfly associates of social Hymenoptera normally have a single generation each year. Therefore, good years for adult hoverflies probably reflect the breeding succes of the preceding year rather than the year in question. This raises the important point that disentangling the ecology of one guild of animals may be dependent upon good data for another group of orgamisms. Are there sufficient data to say how well bumblebees, ants and wasps fare each year? It strikes me that some simple system for monitoring absolute numbers of bumblebees and social wasps might provide important data to help to investigate this relationship. That gets me thinking that perhaps we need more join-up between the HRS and BWARS.