Sunday, 7 May 2017

Do we need a new approach to Hoverfly ID?

For a long while, I have felt that we are missing something with hoverfly ID in the UK, and especially in the case of live animal photography.

Stubbs and Falk has served us very well for over 30 years, but it comes from another era in which it was assumed that species identification would be based on specimens. Today, that is no longer the case, as photography has advanced and the numbers of people recording hoverflies has changed out of all expectations. The HRS was one of the first recording schemes to recognise the potential of photography and the Resident Team on the Facebook page have been active in this field for perhaps ten years. As such, we are pretty experienced. Nevertheless, we regularly encounter good photographs that we cannot take to species. Sometimes we are assisted by Gerard Pennards who we really ought to consider as a member of the team. Gerard brings a much-needed and valued European perspective.

This experience brings me to the nub of the challenge we face. Our current understanding of the UK fauna is based on a sub-sample of the European fauna. Although in places the keys do take account of possible European species, they don't tackle the fundamental problem of how to distinguish tricky photographs where you cannot change the angles to see critical characters. Sometimes we need to see a bit more, and sometimes, perhaps, there are perfectly good features that we don't recognise because our keys are geared to a restricted fauna. European keys often add in couplets to sort out overlaps that don't occur in the UK. This was brought home to me this weekend with a shot of a Parasyrphus that might either be P. mallinellus or P. lineola. The UK key simply concentrates on leg colour but van Veen makes a further separation based on antennal colour. That could be very useful when checking photographs. There are lots of other places where such splits might be helpful.

I therefore think we need to be working towards a new approach to identification of hoverflies in Britain. The current guides serve us well, but we might just do that little bit better and might find ways of improving the level of identification from photographs. That is not to say that we don't need taxonomy based on specimens; clearly there are many places where we cannot avoid the need for specimens. BUT, I think we might just enter a new paradigm if we start to tackle the question of ID from a live animal and photographic perspective.

All I need now is the time to think out the approach! I think it is the sort of thing that could be a really nice opportunity for collaboration between UK and European specialists. There is no doubt the UK would learn a great deal from our European counterparts, but we would also bring important experience to the table.

1 comment:

  1. Roger, firstly thank you once again for all that very evident hard work and much time spent considering issues such as these before you publish for response. As you know yourself and Stuart are primary trainers of myself and my cohort from the my students days (albeit as a very mature one). The approach we adopted did see a number of use us van Veen and others, even a Finnish guide - Haarto & Kerppola as we found the situation you illustrated above, different folks use different set of 'conclusive' characters.

    That HRS has been leading the way through its continued welcome of images and more importantly in my humble opinion the way it they are dealt with. In that the messages attached to the sometimes inevitable 'can't do it it further than genus' images always leave one preparing optimistically for the 'next' time, be it more images showing more features or returning to a specimen and re photographing it to then get the thumbs up.

    You thoughts appear timely in that a number of Channel hopping species, be that due to global warming or jet stream appear to be steadily rising and interacting with experts from where the originate can only enable us better. Count me in if there is anything I can offer that may lessen your workload. M