For several years, I have been trawling the internet for photographs of hoverflies and other Diptera from the British Isles to improve the data available to recording schemes. So far I have extracted almost 9,500 hoverfly records where it has been possible not only to identify the insect but also to link it to a place name and to at least a ten kilometer grid square. In many instances it is possible to get to a four-figure grid reference and as geotagging becomes more prevalent even more detailed records can be made.
During the mid-summer months, this trawl can take as much as an hour a day to cover the breadth of available data. A great deal is posted on Flickr but there are other sites that also yield regular records. Although a good number of photographers provide some data with their photographs, a remarkable number do not. This seems to me to be a great shame as data for even the commonest insect can be valuable. I would therefore encourage photographers to either geotag their photos or provide a note of the locality name (and county) together with the date the photo was taken.
Over 2700 records of hoverflies have been extracted for 2012. This constitutes around 10% of the data now entering the Hoverfly Recording Scheme each year, and is therefore a not insignificant contribution to the dataset. Trawling the internet allows me to undertake biological recording whilst maintaining my presence in the office (work is rather scarce at the moment!). Regrettably, it does nothing to trim my waistline!
How many other recording schemes trawl for data? I know that Matt Smith and Chris Raper do the same for the Tachinidae, and that Tristan Bantock does for the Hemiptera. There are lots of beetle records (especially longhorns) that would be worth harvesting and some Hymenoptera may be useful although the numbers that can be identified are probably low.
This sort of work might usefully be taken on by field naturalists with modest identification skills who could simply search out the data, create a spreadsheet and let others check the identity. Simple spreadsheets for different Orders would be immensely useful. I do this for the Diptera and farm out data for other schemes. Some scheme organisers are quite dismissive of such data, but others may do well. For example, most of the Bombylidae can be done and Malcolm Smart was able to put names to a large precentage of the Asilidae. Even records of common species can be very useful as most schemes have huge gaps in the data for more remote places.
What can the data be used for?Modern biological recording has changed a great deal from the days when it focused on the production of simple distribution maps. Records contributed by non-vocational sources (I hate the term amateur as it has inappropriate negative connotations) can be used in many ways. They are now routinely used to investigate changes in species distribution and abundance, to investigate the possible impacts of climate change and to inform policy makers about the ways in which countryside management is affecting our wildlife. Photographers who provide data with their photos are therefore making an important contribution to our understanding of wildlife trends.
In the case of the Hoverfly Recording Scheme the dataset is now sufficiently big that it provides quite reliable indications of the changing fortunes of individual species and the fauna as a whole. These analyses regularly figure in JNCC work that helps to inform policy-makers and decision-makers. They have been used to undertake species status reviews and have made an important contribution to the redefinition of the Red List for Britain's Hoverflies (which awaits publication at JNCC).
It is not infrequent for recorders to question why there is a need for more than a single record of a species, or perhaps the first and last dates for the year? This reflects the historic role of recording schemes where the main interest was on dots on maps. If we have more detailed data we can do so much more. For example, if one wants to monitor changing abundance or distribution, the animals or plants involved need to be sufficiently abundant to generate meaningful and statistically valid trends. Rare species are often less suited to this than commoner ones.
A great example of this is the hoverfly Epistrophe eligans which flies in the spring. Over the past 25 years, its flight period has shifted dramatically earlier so that today it is frequently recorded in March whereas it would normally have appeared in late April 25 years ago! Understanding the change is helped if we can not only look at first and last dates, but are also able to establish the change in dates of peak occurrence. So, all records are helpful, and photographic records are often particularly useful as they reflect the times when the non-specialist observer sees them in sufficient numbers to attract attention. There are several other spring species that are also useful and others such as the 'Heineken Fly' Rhingia campestris tell an important story about the relationship between invertebrate abundance and drought.
Other examples include the big hornet and wasp mimic Volucella species. Data from non-specialists has helped to track their northward progression in response to climate change. Much of the data we used in 2004 to predict possible changes came from occasional notes in journals and even newspapers that helped to create a picture of these species' fortunes. Today, the increase in use of the internet means that there is now an army of recorders that was previously inaccessible.
Over the coming months I will expand on this theme and will explore the ways in which data generated by countryside observers can help raise the profile of the plight of Britain's wildlife.