Moths – a bit more than just bird food?

Stanislaw Szydlo [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia CommonsI always look forward to reports from Butterfly Conservation – not because they are always full of good news but because they are always very professionally produced, always teach me something I didn’t know and always have the mixture of graphs, images and words that does it for me.

Their latest report ‘The State of Britain’s Larger Moths 2013‘ is just as fascinating as all the others.

Most moths are quite small and quite dull – although that isn’t what the report says!  But this report deals with the larger moths, some of whom are extremely beautiful if looked at in the right way – take a look at the elephant hawk-moth on the back cover for an example (and another image at the head of this blog).

Dull or not, and I’m sure the authors would say ‘not’, and they are the experts, there are an awful lot of moth species and they are of great importance.  Not only are they bird food (as Martin Warren always teases me) but they are also important plant pollinators.

Of the 2,500 UK moth species, 900 are covered in this report and the bottom line is that they have declined in abundance by 28% (despite many individual species increasing) since I was in the top class in primary school (1968).  900 species – that’s not a trivial chunk of UK biodiversity – more species than all the vertebrates put together.

As the report says: ‘The substantial decline of Britain’s larger moths is one of the clearest signals yet of potentially  catastrophic biodiversity loss caused by human impacts on the environment, which is of great conservation concern and potentially threatens some of the ecosystem services upon which the human race depends.’. At first, perhaps, that claim sounds a bit overblown – but I don’t think it is.

And Butterfly Conservation also says; ‘…there are significantly fewer individual moths in Britain now than 40 years ago and, while many rapidly declining moths are still regularly recorded in back gardens and other habitats across the country, their populations are a shadow of their former selves. Like the House Sparrow, Hedgehog and Small Tortoiseshell butterfly, moths that were once taken for granted, such as V-moth and Garden Tiger, are now unusual sightings in many people’s gardens.’. I like that point because it is important for us to realise that it is the everyday, the common, the usual, that is slipping away bit by bit every year, and that after a period of years we look around and realise that there is just far less wild life in our lives.  That is important because the maintenance of biodiversity is a true test of whether we are living sustainably on this planet, in this country and in our local area.  And we aren’t!

And these are two good points too: ‘The future for Britain’s moths is uncertain. Conservation efforts targeted at threatened species have yielded positive results, but more is needed. Funding cuts and shifting government policy (away from the species-focussed UK BAP approach) threaten this hard-fought progress. Likewise, for more widespread species, the optimism that ‘entry level’ agri-environment schemes would see the restoration of wildlife-friendly habitats on a massive scale across the landscape has melted away. The need remains, but tax-payers’ money needs to be spent more judiciously on management options with proven benefits for wildlife and the environment.’.  BC is clearly not optimistic that the rare and localised species can be conserved by targetted conservation action because of cuts and the pathetic nature of Natural England, and they see little chance of the wider-countryside species benefitting from the current implementation of the Entry Level Scheme in England either.  regular readers of this blog will recognise that last view as my own regarding farmland birds – and it applies to hundreds of moths too, it seems.

Two fairly recent reports from Plantlife highlight the dramatic and ongoing loss of plants from our countryside, many of them formerly common and widespread flowers (here and here).  This report, and an earlier one on butterflies, document the dramatic and ongoing losses of insects from our countryside.  And we have almost become accustomed and blase about the dramatic and ongoing loss of formerly common birds from our woods and farmland. When will Defra wake up and extract their digits from wherever they are hidden at the moment and do something about it?

There is no lack of evidence for wildlife loss in our countryside.  There is some lack of understanding about the relative importance of different factors but no lack of understanding of the things that need to be fixed to stop and reverse these declines.  There is no lack of money, through agri-environment schemes, to make an immediate and effective start to putting wildlife on the road to recovery. There is no sign that Defra has a clue what it is doing nor that Defra Ministers have any enthusiasm for doing anything.

Defra: Dire; Egregious; Failing; Risible and Adrift.

V-moth has declined by 99% since 1968. By picture taken by Olei  (Own work)[see page for license], via Wikimedia Commons
V-moth has declined by 99% since 1968. By picture taken by Olei (Own work)[see page for license], via Wikimedia Commons

 

 

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21 Replies to “Moths – a bit more than just bird food?”

  1. Mark,

    Great blog and good to see you championing our moths, which are beginning to get more attention thanks in no small part to the fantastic work of Butterfly Conservation.

    Interested in what you make of the response of Defra's chief scientist Ian Boyd to the moth report. He initially sent a tweet which said 'Interested to see the State of British Mothes Report 2013. Mixed news. Some new species, some old ones gone. Increases and declines' He then wrote a blog 'The great British moth decline - or is it?' http://ianlboyd.wordpress.com/ . This effectively casts his own doubts on the data and that moths are declining at all, ending with the puzzling statement 'the world is changing, but I'm not sure the report really shows this is necessarily bad for moths'.

    So why do Defra want to play down the blindingly obvious, that moths like many other taxa are in big trouble in our countryside? And what motive could Defra possibly have for doing that? Is it because, unlike for birds, their declines cannot easily be blamed on predators (unless we are going to see suggestions for culls of moth-munching passerines). I have often thought that the RSPB should be making more of the declines of things other than birds in the British countryside as part of their advocacy. I wonder how they will use this report.

    By the way, it is not just the larger moths that have beautiful species amongst their number. Many of the micro moths are simply stunning. Why don't you buy a moth trap and find out for yourself? And join Butterfly COnservation while you're at it.

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    1. Mike - thank you for pointing us to Ian Boyd's blog. I didn't find his argument very convincing - it was along the lines of 'the data aren't perfect therefore it's wrong'.

      I'm no expert on moths (nor on most other things actually) but I don't think that Ian Boyd is a moth expert either. I'd back BC's interpretation on these data any day.

      The experience from bird data are quite interesting here - perhaps. The CBC (Common Birds Census) was the original means of measuring common bird population trends and had several of the snags that Ian points out are potential snags with the moth data. When the CBC was replaced by the BBS the period of overlap showed that the much better designed BBS produced really quite similar results to the CBC in the years of overlap. So the potential problem really wasn't that serious in practice. [So was the change-over worthwhile, you might ask? The answer is 'yes' because advantages of the BBS allowed much greater coverage and easier data analysis - as well as taking less observer time].

      If we only had moth data then perhaps we would be cautious in saying that the countryside is bleeding its wildlife - but we have the same picture for farmland birds, butterflies and plants.

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  2. So you set out to kill insects on 70% of your land area (the proportion of England in agriculture) ? What do you expect ? it's even harder to measure the biomass of insects than of birds, but all the evidence points to an order of magnitude decline in moths and probably a whole range of other even less visible insects.

    Yes, Defra is woeful but its time to ask the question as to whether there needs to be a shift in gear on the part of conservation bodies, too. There is a distinct reluctance to ask the big questions, probably because everyone has their heads down dealing with the close up, immediate (and familiar) issues like changes to the CAP. 'Big picture' views are often poorly founded and detached from reality - the flakier end of the green spectrum, but this itself is a huge issue - there is a yawning gap between the theory and practice - you only have to read the reports of Lord Kreb's committee on climate change which basically say that lots of good work is going on in committee rooms but simply doesn't translate to reality on the ground.

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  3. Thanks Mark for excellent blog about this important topic.

    Regarding the two comments made by Mike and Rod. We recently had a good workshop with a range of NGO and statutory organisations to thrash out what we would like to see to help moths, butterflies and a range of invertebrates in the countryside. This was focussed on how ELS might be improved so it actually delivers something for biodiversity, but also improving HLS. Basically we concluded that a lot of the right options were there, but not taken up much by farmers. Also advisers may not know whats best for inverts, so we identified an urgent need for better training.

    Key elements of good management for inverts are: diversity of structure in habitats, including field margins; do not cut everything every year as inverts will be overwintering somewhere and will be killed by it (this applies to pollen and nectar mixes which are routinley cut every autumn thus killing most butterfly larvae that may have been laid there); plant wildflowers in field margins where none are likely to appear through natural regen (ie on heavy soils with no seed bank left); and create other variety on a small scale such as shelter, hedgerow trees, bare ground etc. As you can see by this list there are a few simple messages we need to get across and we will be working to get general advice out soon. This could really help moths and a whole range of widlife.

    Regarding Ian Boyd, we have contacted him to challenge his remarks and are arranging to meet him asap to explain why we believe the data on moth declines are indeed rigorous and need to be taken seriously by Defra.

    Good to get the debate going

    Martin

    Dr Martin Warren
    Chief Executive
    Butterfly Conservation

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    1. Martin - thank you! It's a great report and BC should be proud of it.

      The need for ELS to be thoroughly revamped seems to be clear across taxa. What will it take to get Defra to do something?

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  4. Bit ironic in the present context: New Scientist report that NERC is spending £400,000 on a drilling project to obtain a core sample spanning the gap in the geological record known as the Romer’s Gap to see what happened after the Devonian Extinction event. http://www.newscientist.com/article/mg21729041.900-evolutions-detectives-closing-in-on-missing-links.html?full=true

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  5. Mike - fascinating about Ian Boyd's comments - I wonder whether my comment just after yours could have something to do with his reluctance to accept a decline ?

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  6. In vain I searched the reference list for any study of the evolution of Rothamsted Trap Aversion in Britain's Larger Moths

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  7. It is an astonishing reaction by the DEFRA Chief Scientist to suggest that the report shows that changes in our world are 'not necessarily bad for moths'.
    The report showed a truly dreadful decline overall with far more declining species than increasing/stable species and a whole slew of species that were once common and widespread ('familiar' perhaps is not the word outside the world of moth recorders) crashing by 85% or more since the 1960s including V Moth, Mouse Moth, August Thorn, Grey Chi... It is extraordinarily complacent to just shrug this off.
    What the report did show is that there is a striking difference between the north and the south of the country (around the York - Lancaster line) with the really catastrophic results applicable to the south of the country and the north showing no clear pattern. Why this is is not entirely clear but could perhaps be because there is a higher proportion of non intensively managed land in the north. However, the data only allow for a very coarse grained comparison of north v south and I would not be at all surprised if a close examination of the north of the country (if the data were available to make the analysis) would show that in the intensively farmed areas moths are declining here too.
    As Roderick points out it is no surprise that insects should become scarce if we use insecticides widely across vast areas of the countryside but it is also the case that through herbicide use and fertiliser use we have hugely reduced the botanical diversity of the countryside which ultimately must support the diversity of everything else. This report should be taken as a huge warning bell and sitr DEFRA into decisive action but it seems that is too much to hope for.

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  8. Can I suggest a glass-half-full, thought-experiment way of looking at this. Suppose the intention of one of these typical RIS traps was not to survey numbers but to exterminate all moth-life in that immediate area. Would not the trapper be entitled to feel disappointment that after more than 40 years of continuous nightly running he'd "only" managed to lessen numbers by 28%? Especially when it was pointed out to him that perhaps there had been some aversion-to-light evolution going on during those 40 years.

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    1. Hi Mike

      It is worth pointing out the Rothamsted traps are deliberately low light level and trap an insignificant aount of the moth population, thus have no impact on numbers. We also tested to see whether light pollution was affecting trap efficiency, and it wasn't, at least traps in dark areas still showed similar declines in moths.

      Best wishes

      Martin

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    2. Mike, I remember car journeys as a child in the 60s when the headlights picked out clouds of moths and the windscreen was plastered in squashed remains of moths. I've not seen anything like that for many years. Can we postulate moths have evolved excellent road safety skills? Or is car aversion a better description? My suspicion is that population crashes are a more likely explanation.

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  9. Not wishing to take anyone off topic but the (slightly) related link illuminates the rather too strong a relationship between government ministers in Scotland and the country's farmers, or at least those who are NFUS members

    http://www.andywightman.com/?p=2172

    A nice graph too.

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  10. Martin agree with your comments but my role on this blog seems to be in representing farmers theses days. Don't forget to talk to us about redoing ELS (us not NFU). The problem with Defra is as been said on this blog a few times and by TR "it's easy to farm when your plough is a pen and you're a thousand miles from a corn field" !

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  11. Thanks for the link to Ian Boyd's blog. He suggests a number of ways in which the data might be biased, but strangely he also cites the paper by Conrad et al. 2006 where potential biases were addressed, although he ignores that. In particular, the issue of habitats having changed during the course of the study is picked up:
    "Because of trap turnover, the relative numbers of different types of biotope sampled each year varies over time. The mean annual proportions of sites used corresponded with the following categories: coastal (8.9%); farmland (13.5%); mixed (15.3%); moorland (3.1%); parkland (22.8%); scrubland (2.6%); urban (15.9%) and woodland (17.8%). Only the proportion of scrubland changed significantly over time (F1,33 = 30.34, P < 0.001), and this is largely because no traps were sited in areas that were categorised as scrubland in the early years of the study. Annual variation in biotopes sampled was not systematically biased in any way."

    Martin Warren and colleagues will be able to mount a stronger defence of the State of Moths report than I can, but as a county moth recorder I can only say that the science-based conclusions in the report seem robust to me, and chime with my own more anecdotal experience of recording moths over the past 36 years.

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    1. I posted a similar comment to the above on Ian Boyd's blog on Tuesday evening, it is now Thursday morning and the comment has not been allowed to appear, and no other comments have either (Boyd's original blog post was on Feb 7th and I find it hard to believe that no-one has commented on it since then). I'm sure he's a busy person, but having gone to the trouble of setting up a blog to cast doubt on this research it's intriguing that so far he's not interested in the interactive side of blogging!

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  12. The current environmental trends are now monitored from as far as away as possible.! If you look in detail (eg at moths or even birds) you will see the bad news.....but if you look at the UK from satellite then everything looks nice and green.
    Its a form of monitoring which hides the truth- hence it is preferred.

    The "ecosystem services" approach is being used to undermine site based conservation. I believe that in Scotland, SNH's anti-conservation board is trying to persuade staff that designated sites are a bad idea!

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  13. Well I followed the link and read Ian Boyd's blog post and I agree with parts of it.

    The report does gloss over a lot of background data manipulation - as summary reports do - that needs to be shown to an idiot like me before I accept what it is that I am being asked to believe. In particular I would like to see the raw, messy, non-indexed, un-normalised, gappy stuff before software has cleaned it up and inserted calculated missing values. No doubt it exists somewhere in the referenced papers but frankly I just don't have the time and the incli ...

    I think Boyd is right to say that care is needed when interpolating trends to overall trends - but I would have used "extrapolating" - and the results are only (?) for larger, nocturnal moths captured in the Rothamsted traps.

    I think Boyd is wrong to assert that choosing areas of highest abundance can only show two responses – stability or decline – in a dynamic landscape. What happened to increase?

    But this is nitpickery - mostly I see the words of someone instructed to prepare an exit strategy. When a scientific report uses such overworked words such as "potentially catastrophic, overwhelming, unequivocal" it's bound to fire-up someone's spin receptors. Best not to do it. The current gang may have more critical faculties than Prezza and the Milipedes.

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