Adding a bit of structure: moth monitoring and the Garden Moth Scheme

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Last Sunday I attended the excellent annual conference of the Garden Moth Scheme, which was well-attended, informative and enjoyable. And most importantly it showed how valuable it can be to record in a slightly more standardised way that we might otherwise do. Read on for more on the benefits of structured recording, and how you can join in with GMS.

Lots of people record moths and send their records in to their county moth recorder, which is an excellent way of finding out which species are where and contributing to the National Moth Recording Scheme. However, using this data for monitoring purposes is not straightforward, as there are so many variations in how, where and when people record their moths. To get good data on population trends for moths a more structured approach is needed.

Mean annual catches of the longest running RIS trap (Barnfield), in 3 year categories, compared with average values for RIS arable and grassland sites.

Mean annual catches of the longest running RIS trap (Barnfield), in 3 year categories, compared with average values for RIS arable and grassland sites.

The largest-scale example of structured moth recording is the Rothamsted Insect Survey (RIS), which celebrated its 50th anniversary in 2014. One of the RIS projects gathers data from Rothamsted moth traps positioned around Britain and Ireland. The first of these traps was used in the 1930s and 1940s, and following a gap in the 1950s an extensive network has been developed since the 1960s. This has provided an unparalleled set of long-term monitoring data for moths, and unfortunately what the data tell us is not very good news: the one trap that was running before the second world war was producing a lot more moths than traps have done subsequently, suggesting that there was a major decline in moth abundance in the 1950s (see graph on right). And the declines have continued: Rothamsted data was used in a joint project with Butterfly Conservation to assess the State of Britain’s moths over the last 40 years, from which the headline news was that two-thirds of widespread moths have undergone a significant decline, especially in southern Britain.

The Rothamsted moth traps are run by a network of volunteers, and new volunteers are welcome, but it is quite a big commitment. You have to have space to install the trap, and you have to commit to running it every night of the year for at least five years. Many of the Rothamsted traps are situated in places such as Field Studies Centres or research institutes.

GmsBut there is another moth monitoring scheme that you can join in with much more easily. The Garden Moth Scheme asks its participants to run a moth trap once a week (on the same night each week if at all possible) and to record the numbers of a suite of common species (you can of course record all the species you see if you wish, but the GMS focuses on a main list of around 220 species). Even if the weather is unpromising it’s still important to run your trap, and if you have a night where you record no moths that is still useful data! It is this regular pattern of recording once a week whatever the weather that helps give this survey its structured data, and allows for robust analysis of the results.

The GMS is an entirely volunteer-led project that has been running nationally since 2007, and the data it has collected is building up into a major resource. A recently published paper uses GMS data to show that gardens containing more diverse habitats have more moths, gardens near the coast have more on average than inland gardens, and gardens in urban areas have fewer moths on average than non-urban areas. These results are not perhaps very surprising, but the GMS data allows the trends to be quantified and investigated further. The full paper is open-access, see: Bates, A.J., et al. 2014. Garden and Landscape-Scale Correlates of Moths of Differing Conservation Status: Significant Effects of Urbanization and Habitat Diversity. PLoS ONE 9(1): e86925. doi: 10.1371/journal.pone.0086925.

A previous paper looked at the effects of different designs of moth trap and different bulb types to compare the catches of each (Bates, A.J., et al. 2013. Assessing the value of the Garden Moth Scheme citizen science dataset: how does light trap type affect catch?. Entomologia Experimentalis et Applicata, 146: 386–397. doi: 10.1111/eea.12038 – unfortunately this one isn’t open-access), and members of the GMS are busy looking at the data in various ways to pick out trends and report back to the participants via regular newsletters and annual reports. Over time the data will become ever more useful and will allow for further research.

Moth trap in my former garden in Berkshire, and the best garden I've ever had for moths - sadly, where I live now is much less good!

Moth trap in my former garden in Berkshire – sadly, where I live now is much less productive for moths!

All in all the GMS is an excellent way for moth recorders to add an element of structured monitoring to their recording, without doing anything other than running a moth-trap in the garden, the sort of thing that moth-recorders love to do anyway! If you want to join in for the 2015 you need to be quick – recording is due to start this coming Friday 6 March (although at a push you can start a week or two later if you miss that first deadline), so head straight over to the GMS Getting involved page. I’m going to give it a go this year, and I look forward to seeing how my results fit in with everyone else’s.

If you do take part in GMS, please remember to copy your results (along with all your non-GMS moth records) to your county moth recorder as well.

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