Thursday, 26 October 2017

The moth snowstorm and insect decline

Having just listened to Adam Rutherford's piece on insect decline on Radio 4 tonight I was reminded of my early days as a moth enthusiast. One night in around 1983/4, the late Steve Church (who founded Bioscan UK) and I went to Salcey Forest. We arrived after dark as Steve was never very reliable with his time-keeping! But, perhaps that was fortunate because I well remember the absolute blizzard of moths in the headlights that night! Equally, I am reminded of the wonderful flight of the Ghost Swift moths along the edge of Mitcham Common in July those days. I don't remember when I last saw a Ghost Swift, let alone dozens bobbing around in the gloom.

But, again, I heard a bit of under-play of current levels of recording from Dave Goulson, who commented that we have good data for butterflies and moths, and less reliable data for bees. I do wish that a bit more attention was paid to what actually goes on - we don't lack biological recording but we do lack the tightly regulated monitoring that might be achieved by an expensive long-term study. So, do I detect a bit of propaganda here? I am reminded of a meeting with another academic group that was proposing to seek a research grant to investigate the distribution of Horseflies in the UK who had not even heard of the relevant recording scheme that had been running for way over 30 years!

To be fair to Dave Goulson, he did mention that there were data for bees, but he might also have mentioned that there are around 80 long-term voluntary data collection programmes for Britain's biodiversity and that the UK pretty well leads the World in the use of non-vocational data collection. Despite this, we don't have the data that the German 'Amateur' entomologists have gathered (I hate the term 'Amateur'); but just take a look at the volume of data on GBIF and you will find that for almost all taxa the UK is a bright red mass when compared to the rest of Europe, let alone any other parts of the World. Those data are actually pretty powerful for quite a wide range of invertebrates and have been used in many studies that have identified equally worrying trends in invertebrate abundance.

And, sorry to say Dave, if the data for bees are ok but limited, those for hoverflies are probably rather more robust! As I recall the HRS and BWARS hold roughly similar datasets in terms of numbers of records, but whereas BWARS covers perhaps 550 species, the HRS covers 283 species! We now hold well over a million records (but with some duplication). So lets see some acknowledgement of those other schemes that regularly provide good quality data for academics and Governments to make use of; and we do it all for nothing!

A more critical message

I will, however, concede that we and others could have made a lot more noise about the issues of insect declines and that the German data do tell a particularly important story that does not get picked up in UK data. The big point that the German data tell us is the absolute biomass change and that is critical. Sadly, UK recording schemes don't give us this sort of result and it is of massive importance.

Declines in individual species using occupancy models mask the scale of decline that is potentially happening: if they rely on presence/absence, then one record for a 1km or 10km square is equally significant and does not change the model. So, somehow, the next generation of models needs to take account of absolute numbers of records. Add to that, we desperately need to see far more reliable day-to-day recording so that changes in the relative frequency of individual species can be detected. I have previously used the case of the Passenger Pigeon and perhaps there are analogous species in the insect World that are heading in the same direction? Just because it is common does not mean that it is not worthy of recording!

Do we need more funding?

It would be easy to say yes, but I think we have got other work to do that does not involve funding. It requires the recording schemes to make a concerted effort to break the community of natural historians away from a fixation on rarity and upon dots on maps; both of which are a problem if one wants to get a decent dataset that tells us something about overall population changes.

So, as a first step, let us see more recorders making daily counts of the animals that they see. Please try to note full lists for each day rather than just the highlights. For me, this is the great benefit of BirdTrack and as such I want to see the HRS move in the same direction. We really need a network of recorders who record all species on as many days of the year as possible.

Similarly, we also need to generate a much bigger base of people who can identify the full range of species, or who are prepared to retain specimens for technical specialists to analyse. For me, the recent publicity on insect decline highlights the importance of reliable data collection and the importance of whole assemblage data. It shows how the 'take nothing but photographs, leave nothing but footprints' approach leaves conservation science weakened so that we cannot provide the robust messages that the German dataset has provided: full marks to our German counterparts!

Now all we have to do is to move the goalposts and start hitting those targets: that means we need more competent invertebrate taxonomists, which in turn means that there need to be incentives for people to invest the many years that it takes to become taxonomically competent. Perhaps at last we are starting to realise that if you cut soft targets, they start to become a weakness in the system many years later that cannot be rectified just by throwing cash around!


  1. How about a bit of action to reduce and eliminate insecticide and habitat loss. The data is already there to support it.

  2. That is not what I was writing about - there are plenty of organisations to do the action if they feel so moved. The job of the Recording Schemes and people like me is to make sure we have an adequate flow of data - I don't have the time to do both and have no funding so all I would be doing would be expending hot air into an already over-heated climate!

  3. The thing that enrages me is that if you ask any naturalist over say 55 years old, they will tell you, anecdotally of course, that declines in all wildlife, and certainly of invertebrates have been absolutely catastrophic. Tales of insect splattered windscreens, number plates, and helmet visors abound from the 1970's. There are also tales of moth snowstorms, being unable to leave windows open with lights on, lest rooms fill with moths, craneflies and other beasts that would keep you awake all night; masses of beetles and moths at lit shop windows at night - all now a distant 40 year old memory. And still the cry goes up, “we need more data, we need more scientific evidence”. Meanwhile the situation is proceeding from catastrophic to insect "end times" and we (recorders, government departments, wildlife conservation organisations) faff on about data. We desperately need to get on now with doing something about a disastrous situation. It's surely time for action to reverse the awful trend, rather than looking for more evidence? Why can't we just accept the testimony of thousands of knowledgeable and trustworthy naturalists and indeed tens of thousands of laymen who can tell us all we need to know about how much we have lost?
    Rant over! But I am just so fed up with the inaction and hopelessness of it all.

    Needed to get that off my chest....

    1. PS no criticism of your very thoughtful article intended Roger.

    2. That is fine Nigel but unfortunately we all know how anecdotal information is treated, let alone good science - just look at the way the Trump administration ignores sound science and backs its supporters.

      Who is going to take the action? Not you, not me. All we can do is to make sure that the best data possible are available. It is down to the likes of our erstwhile employer to place the evidence before Government and get something done. OR there has to be mass popular action. BUT, whilst I think Dave Goulson was doing a good job in raising the issue, he does so by effectively saying - there is a problem in Germany but we don't have adequate evidence to say what is happening in the UK - in other words he has effectively shot the British argument in the foot rather than pointing out the very considerable evidence from the UK.