Decline of the Wall - fascinating article.

[peterc]

Very interesting arguments put forward here. My take on it is that since coastal areas have generally milder winters than inland sites I suspect the impact on the Wall is minimized for third-brood caterpillars which are more likely to survive until the following spring and therefore coastal populations remain relatively stable. I am assuming that no other factors play a part like parasitism or predation of the larvae. Just a thought.

Peter

[Essex Bertie]

We did some work on the Wall Brown for our branch newsletter (Cambs & Essex) in 2011 as we noticed a shift in phenology both over time (last 2 decades) and between ‘Fenland’ populations in the north and ‘coastal’ populations in the south along the Thames.
We also got some help from a couple of experts, including Leonardo Dapporto in Italy. His observation in the Mediterranean was that the Wall’s phenology can vary quite a bit between micro-climates just several miles apart. So any over-wintering problems at one site might be ‘replenished’ the following year from relatively nearby.
So we surmised that further north, i.e. the UK, these differences in phenology occur regionally rather than locally and so the problems with ‘half-broodedness’ in the autumn are not so easily overcome. So any long-term, consistent ‘half-broodedness’ could result in regional extinction - hence the big fluctuations, historically.
So the survival strategy works in the heart of its range ( nearer the Med), but at the northern fringes, it’s a bit shaky. Climate warming can still help the Wall to spread northwards and upwards in altitude in its bivoltine state, but it might leave some distribution gaps behind it. And if you take it a stage further, there’s arguably an even bigger geographical split between bivoltine and univoltine Walls with the evolution of the Northern Wall Brown (Lasiommata petropolitana).

[HarassedDad]

Let's assume that the Wall population is genetically isolated from the continent and has been since the development of the channel. (Ie no Walls are immigrating along the south coast). So if anyone has records of migrant Walls this falls apart.

If the original colonisation was relatively small and occurred close to 6000BC, when the Uk was finally cut-off, then we could see a "founder effect", where the UK population contains only a subset of the full genetic diversity of the european population. It could be, therefore, that the whole UK population has the same variant allele for the gene responsible for controlling winter diapause. (We know that the decision whether to stop growing for the winter, or continue to emergence, is controlled by endrocrines, and that they are triggered by ambient temperature. It's likely that different variants of the gene result in different "trigger temperatures".) If there is a lack of genetic diversity then natural selection has nothing to work with - it can't select in favour of variation that isn't there. And the research seems to suggest that the critical difference might be as small as 1 degree C rise in average temperature.

So the decision to "choose" two or three broods is entirely controlled by ambient temperatures sampled by larvae in September. If it's cold they stay as larvae till next year, if its warm enough they go for emergence. And crucially all UK Wall have the same trigger temperature (unlike the european populations)

Living in Norwich I'm frequently struck by how much colder it is at the coast than inland in September - I can frequently set out in warm sunshine only to find it's cold, damp and foggy once I get 10 miles from the coast. Co-incidentally that change in temperature roughly maps to where the Wall are. So at the coast, the caterpillars over-winter, here in Norwich any Wall that were here would go for a third brood. But if there's insufficient warmth for long enough for them to reach maturity they may be too far gone to undergo diapause successfully and die. The result is no Walls in Norfolk except around the coast. (Which is what we find)

Now the problem is that we have had climate variation before, so why hasn't this happened earlier in our history: in other words why did we find Wall in the midlands in the first place? Let us assume that the above is all true, and step back to say 200AD, and assume there was a similar run of warm septembers. What would happen is that the Wall would again be "fooled" into attempting a third brood in the warmer areas and would again die out everywhere but the coast. Crucially however, back then, when the run of warm summers ended the population would simply re-expand back into the vacant areas. So it's possible that the distribution of the Wall has ebbed and flowed around the UK over centuries, following the average regional september temperatures. It's simply that we have only been looking in detail for around 40 years, and that at a point when "the tide was going out" as it were.

Of course the big problem this time round is habitat fragmentation - there may not be the access nowadays for the recolonization to take place because there isn't the unbroken countryside to allow the Wall to make its way naturally from the coast back to the interior. It might be that conditions in some areas are now either warm enough to allow a successful third brood, or cold enough to ensure only two, but the butterflies can't get there now because there's a bunch of motorways and towns in the way.

It would be interesting to attempt an introduction of Wall into an area further North than their current distribution. If the theory is correct than they should be perfectly happy now in inland areas in Scotland where the temperature's have reached the sort of range that the midland's had in the 60's. If however, there is something else going on, that involves the coast being somehow "better", other than purely temperature, than the introduction would fail. Alternatively, if the hypothesis is correct, than we ought to start seeing a recolonisation of sites from the south as temperatures get hot enough for three broods to be reliably successful.So we ought to start seeing firstly the distribution to stabilise in the south (no more local extinctions), and then slowly regain sites in Dorset, Sussex and Kent. Meanwhile I'd expect populations in south Yorkshire to start to disappear in inland sites as they warm up to the critical point.

[Tony Moore]

Near Birmingham, in the early fifties, the Wall was close to the commonest butterfly, alongside the Meadow Brown. Its decline was concomitant with the appearance of myxomatosis, an aspect which I hadn't considered before, but which now seems a possibility. The species is now showing some signs of recovery in the Midlands, I think. Interesting stuff.

Tony M.

[Goldie M]

In Southport on the sea front near to the Bird wild life area there used to be a loading station where various trucks went backwards and forwards to the beach to pick up sand which was packed off to various places, behind this station is a shallow quarry, the entrance is narrow but high and gives perfect protection from the cold winds that come off the sea, the rest of the place is quite shallow and just a short couple of steps takes you onto the side where you can walk round and see things at your leisure , since the site closed down and the station was dismantled it's become Ideal for Butterflies especialy the Wall.

It's also an haven for Rabbits infect my Wall photos were taken just outside one of their burrows, I'd been to the Southport Dunes which are much lower down the coast and not seen any but this year and last year I got my first shots of them in Lancs
and was told by other people that they're seeing lots more now since the station was taken down mostly at the entrance of the small quarry where it's sheltered, I intend to go there next year at various times to see just how many I can spot, (that could be interesting) Goldie

[Neil Hulme]

Hi Essex Bertie/all,

"We also got some help from a couple of experts, including Leonardo Dapporto in Italy. His observation in the Mediterranean was that the Wall’s phenology can vary quite a bit between micro-climates just several miles apart. So any over-wintering problems at one site might be ‘replenished’ the following year from relatively nearby.
So we surmised that further north, i.e. the UK, these differences in phenology occur regionally rather than locally and so the problems with ‘half-broodedness’ in the autumn are not so easily overcome. So any long-term, consistent ‘half-broodedness’ could result in regional extinction - hence the big fluctuations, historically."

The mysterious problems facing the Wall in recent years might well be due to a number of factors, as suggested by others. However, I don't think the data (at least in Sussex) support the idea that phenological differences are regional, rather than local, in the UK. Here's an excerpt from my 2014 Personal Diary:

"Thanks Bob [badgerbob]. I agree that the early start to the season (helped no doubt by good weather, including this Indian Summer) has encouraged a full-blown and strong third flight, rather than a 'partial' brood, but I'm not seeing them on all Wall sites. The third brood still seems to be restricted mainly to the warmer locations (at least in West Sussex), whereas the north-facing, cooler sites lag behind just sufficiently to preclude an autumn emergence. That said, I'm sure you're right in saying that some locations, which sit between these two extremes, are producing autumn Wall, when they usually don't. There are probably more of these 'intermediate' sites on your East Sussex patch than I have over my way, as you have much more open downland with west and east-facing aspects.
The most striking example in West Sussex is the difference between Mill Hill and Steyning Rifle Range, with second brood Wall on the latter site lagging 10 - 14 days behind the former, despite being only about 8 Km apart. That difference in timing appears to be just enough to discount a third brood at Steyning (I've looked), despite a burgeoning population. It's a case of 'nearly, but not quite'. I'll be interested to read your Species Champion account this year, particularly an analysis of the wider occurrence of these atypical, late Wall."

BWs, Neil

[IAC]

A few years ago here in the South East of Scotland a Wall Brown was a very rare sight indeed. I became interested in butterflies at about the time of great transitions from south to north of several species. The Wall Brown was one of the first to colonise back then, and it was strictly a coastal butterfly. From 2004 through to 2010 the Walls gradually increased there coastal foothold to become one of the more common local species. From 2011 to now the Walls have started a gradual move that is quickening, to move inland at least 20, 25 miles. I would say that the original vanguard has passed us by now and the northern limit is now likely to be Fife. The coastal preference for this species I have always put down to an unbroken habitat corridor from south to north and vice versa. The butterflies then started using inland corridors such as road side verges, railway lines and river systems. For a few years they stayed put....however this past few seasons has seen them breaking out of the corridors to more isolated spots. In August they can be found in far greater numbers. I even had a few visit the Buddleia in my modest wee garden...9 miles inland. How far they venture inland is still to be seen. They emerge about early May on average, and again early August. As I said the second brood can be quite size-able.
When you consider the other species Speckled Wood, Large Skipper, Small Skipper, and Comma have all now conquered the south east of Scotland and are all headed further north now. Comma and Speckled Wood especially....you would think that would be affecting the homegrown butterflies, if indeed some sort of climate problem existed, especially Northern Brown Argus, Large Heath, Small Pearl Bordered Fritillary. On the contrary all these butterflies are having record seasons. Northern Brown Argus was one butterfly species that was mooted to be under considerable threat as the climate warmed....no sign of that at all so far.
I have attached a chart for the past 4 seasons showing a huge rise in Wall numbers in the Eastern Borders. The wet season of 2012 did not slow them down that much. I visit the same sites very regularly each season over a relatively small area. I can see changes in butterfly density very vividly, but that quite often does not correlate with numbers recorded. As an example, Meadow Brown and Ringlet distribution has collapsed this past few years, yet, numbers are steady. Theses species seem now to be concentrated in high numbers on the coast and are losing ground inland...is there a similar problem affecting Meadow Brown and Ringlet up here as is affecting the Wall down south?. I am hearing from no one else seeing changes in the overall distribution of Meadow Brown and Ringlet locally...but I am sure I am not imagining things.

Interesting stuff.

Iain.

[Essex Bertie]

Neil,
Thanks - that's a really useful observation from the Sussex Downs. Your area fits more with the Mediterranean model as you have south-facing downland next to north-facing escarpment, both with long continuity of habitat. This is really good news if the idea is correct as one or tother will always be in a good overwintering position and should assure the Wall's future there. There might be something similar happening heading south-west as the north and south coastlines get closer. Our initial observations were based on records from the Cambridgeshire Fens and Essex (Coast & Inland), geographically much more of level playing field. What we found was that the fenland populations in the north were fundamentally 2-brooded and the counts were fairly similar between spring and summer broods. Whereas along the Thames there was always a partial third brood of varying magnitude. The spring brood was then very weak but recovered in the second brood. So we concluded that everywhere in between was getting a bit stuck between broods. Not something that would wipe them out in a single season, but enough to push them into decline over a number of years. We also assumed that good Wall sites on the South Coast like Bindon Hill were primarily 3-brooded and could expand back inland with further climate warming. Too big an assumption possibly. It's difficult as the transect season stops just at the critical point. I've only read an excerpt of the Maes et al Study but it takes things to a whole new level.
The other expert that helped us was Prof. Roger Dennis at Staffs Uni. He said that the Wall was making gains in altitude in Cheshire. So I'm reading the Scottish story with interest (IAC).
I think there's quite a lot of us on the same bus here, maybe not just all facing in the same direction.
Best wishes
Rob

[David M]

Some remarkable contributions on this thread from 'amateurs' which just goes to show the level of understanding of butterfly behaviour so many of UKB's members possess even though few would consider themselves to be scientists.

I particularly like 'Harassed Dad's' comprehensive post regarding the potential for the difference in temperature between the coastal strip and the area more than 10 miles inland to effectively represent a 'delimitation' zone for whatever is going on in the evolution of the UK Wall Brown.

Whilst such comments are persuasive, they do not address the phenomenon in its entirety.

Here in south Wales, Wall Browns can be found fairly reliably around the coast. However, the Swansea region's 'coastal strip' rapidly gives way within 15 miles to 250-500m hills. We all know that Wall Browns are prone to seek altitude yet in spite of Graylings being regularly found in this type of habitat, the Wall is conspicuous by its absence.

Given that the ambient autumn temperatures at, say, 350m in autumn are surely no warmer than they are near the coast, I have to ask why is it that the butterfly continues to populate the area close to the coast but no longer does so 15 miles inland at 250-400m?

Apart from Kilvey Hill in Swansea (which is 163 feet high and is less than half a mile from the seashore), I know of no other upland location near to where I live where Wall Browns can be found at all.

Even worse, the area where I used to live was in the hilly areas of Gwent not far from Ebbw Vale. In three years I never saw a single Wall Brown even though the area immediately around me extended to 600m altitude and contained lush grassland habitat which Wall Browns ought to feel at home in.

The inland demise of this butterfly in the course of my lifetime is the biggest puzzle I know as far as UK butterflies are concerned.

[Essex Bertie]

Hi David,
I too have found difficulty in explaining the Wall's virtual extinction from the north-east and Central Essex Coast; once strongholds of the species. Its continued presence along the North Thames corridor (I.e. South Essex Coast) may be short-lived and it is only just surviving the development trap through good continuity of optimal habitat, I.e. Numerous post-industrial sites. So I try and take a broad-brush approach. If the inland habitat in South Wales was once suitable for Walls and you have no reason to suspect its make up has changed, it may still be sub-optimal compared with coastal habitat. In which case, it might suggest that the species is under pressure from the development trap in the region generally. It then takes on the role of a faux specialist (a term possibly coined by Prof. Roger Dennis) seemingly only favouring optimal habitat, but would repopulate sub-optimal habitat if climate change tipped its trend in a positive direction.
When the Wall was found inland, was it vastly more numerous on the Coast? And if you are not getting a partial third brood, is your spring emergence getting smaller and/or earlier?
Regards
Rob

[badgerbob]

I have been meaning to join in this discussion for a while now as I have been the species champion for the Wall Brown in Sussex since 2009. If the 3rd brood is the downfall of this species it may show up in 2015 as the 3rd brood has just had its strongest showing here by an enormous amount. Most years there are only 3 regular sites (all South or South/West facing slopes) where small numbers of 3rd brood can be seen, and in some years even these sites produce none of this late brood. These sites are High and Over, Greenway Bank and Mill Hill. In 2009 they were also seen at Chanctonbury, Castle Hill NNR and the Ouse Estuary Project, but in all cases in very small numbers. Small numbers again were seen only at High and Over and Mill Hill in 2010. In 2011 higher numbers were seen, but once again only the 3 strongest sites. Numbers just into double figures were seen at High and Over, the best 3rd brood site. In 2012 there was only one confirmed sighting, this one was a single female at High and Over again. No 3rd brood were seen at all anywhere in 2013. However, as already mentioned 2014 was always looking good for a strong 3rd brood with the 1st and 2nd brood being very early. However, even the most optimistic butterfly watcher could not have anticipated how big this brood would be with many sites producing very good numbers into the 30s. These sites included many that were not on the Downland slopes with many butterflies seen on Pevensey Levels and the lower River Cuckmere valley. It seems only the North facing Wall Brown sites produced no 3rd brood. I try to do several Wall Brown counts throughout the year in the best stronghold around Seaford where during the 2nd brood I can get between 60 and 100 butterflies on my 4 mile circuit. If numbers collapse in 2015 on these counts maybe that will be a sign of the 3rd brood being bad for the following years numbers. There again it could just be that after many years of numbers increasing a collapse is due soon anyway!! I suppose if numbers crash on my main circuit, where a good 3rd brood was very evident this year, but numbers remain very good on the North facing sites where no 3rd brood were seen this would perhaps give some evidence to this theory!! Whatever happens I am looking forward with extra interest to studying this butterfly again in 2015.

[Essex Bertie]

Hi Badgerbob,
Our newsletter article was entitled "Wall Brown - 2 and 3 broods ‘Good’, 2.5 broods ‘Bad’?" as we thought that full broods (either 2 or 3) would result in good over-wintering success of larvae. So I will be watching your web sightings with interest. We too had what must have been a full 3rd brood along the Thames in Essex. Normally third brood counts are in the 1 to 7 range, but this year we had sightings at 2 sites of 18 and 20. The hope is that all eggs would have hatched during the second half of September and into the warm October when temperatures remained high until the end of the month. However, we cannot be certain how well the larvae can over-winter in the early instar, so it could still be catastrophic! But we are of course hoping for a rare strong first brood.
cheers
Rob

[Matsukaze]

Some remarkable contributions on this thread from 'amateurs' which just goes to show the level of understanding of butterfly behaviour so many of UKB's members possess even though few would consider themselves to be scientists.

I particularly like 'Harassed Dad's' comprehensive post regarding the potential for the difference in temperature between the coastal strip and the area more than 10 miles inland to effectively represent a 'delimitation' zone for whatever is going on in the evolution of the UK Wall Brown.

Whilst such comments are persuasive, they do not address the phenomenon in its entirety.

Here in south Wales, Wall Browns can be found fairly reliably around the coast. However, the Swansea region's 'coastal strip' rapidly gives way within 15 miles to 250-500m hills. We all know that Wall Browns are prone to seek altitude yet in spite of Graylings being regularly found in this type of habitat, the Wall is conspicuous by its absence.

Given that the ambient autumn temperatures at, say, 350m in autumn are surely no warmer than they are near the coast, I have to ask why is it that the butterfly continues to populate the area close to the coast but no longer does so 15 miles inland at 250-400m?

Apart from Kilvey Hill in Swansea (which is 163 feet high and is less than half a mile from the seashore), I know of no other upland location near to where I live where Wall Browns can be found at all.

Even worse, the area where I used to live was in the hilly areas of Gwent not far from Ebbw Vale. In three years I never saw a single Wall Brown even though the area immediately around me extended to 600m altitude and contained lush grassland habitat which Wall Browns ought to feel at home in.

The inland demise of this butterfly in the course of my lifetime is the biggest puzzle I know as far as UK butterflies are concerned.

The Wall can be found at similar sorts of altitude 10-15 miles inland on the other side of the Severn estuary, on Exmoor. It is a bit sporadic there and by no means common, but usually turns up there in ones and twos.

Incidentally we saw a couple of third-brood Wall in mid-September on and near the south Gower coast - no idea if this is a usual timing for the species.

[Jack Harrison]

A fascinating discussion and for once a species' decline doesn't seem to be linked to loss of habitat. Unlike Duke of Burgundy, Peal Bordered Fritillary, etc, where habitat management seems to be key to the success, the Wall is providing a real-time experiment in the unexpected effects of climate change. A perfect study for a would-be PhD.

The Wall Brown has been recorded on Mull in recent years but I have so far had no luck myself. I suspect it was an isolated sighting and probably a wind-blown vagrant from NW Ireland or SW Scotland. But I live in hope.

Jack

[peterc]

A fascinating discussion and for once a species' decline doesn't seem to be linked to loss of habitat. Unlike Duke of Burgundy, Peal Bordered Fritillary, etc, where habitat management seems to be key to the success, the Wall is providing a real-time experiment in the unexpected effects of climate change. A perfect study for a would-be PhD.

The Wall Brown has been recorded on Mull in recent years but I have so far had no luck myself. I suspect it was an isolated sighting and probably a wind-blown vagrant from NW Ireland or SW Scotland. But I live in hope.

Jack

I agree with you, Jack. The more I think about the demise of the Wall, the more I am convinced that it is mainly due to climate-change which may be more pronounced inland than on the coast where the sea nullifies it to some extent (cooler summers and milder winters generally on the coasts). But have I missed something?

Just to think I used to see them in the back garden in Hove (on the wall of course!) in the 1960s.

Peter

[Jack Harrison]

One thing I do disagree with about this thread. It should have been entitled: "The writing is on the Wall".



Jack

[Neil Hulme]

This is an interesting topic and it’s great to see so many well-reasoned posts on the subject. Returning to my earlier comment (and those of others), I do believe that more than one factor may be at work here. I also believe that the researchers are on to something with their ‘lost generation’ theory, and this may well be one of the main drivers.

Moving away from Sussex, where localised microclimate differences on either side of the Downs play an important role in dictating phenology, it seems clear that higher average temperatures have historically encouraged inland colonies to more often produce a third brood – apparently a high risk strategy.

But what is it that actually causes the suspected high failure rate (in SOME years) in the smaller over-wintering caterpillars produced by a third brood? The researchers mention that “Under unfavourable autumn conditions, the attempted third generation will result in high mortality and eventually a lost or ‘suicidal’ third generation ....”. In the section of their paper I currently have access to, there is no speculation as to what these unfavourable conditions might be. This might be one of several important areas to research in the future, with the necessity for further research being widely acknowledged.

I think it may be important to look at temperature trends across different sections of the year, and certainly more than either average annual temperatures (and e.g. humidity), or average temperatures preceding the point at which a larva will be triggered to either diapause or continue developing into a third brood adult. I suspect the winter period may be very important in determining the outcome for small caterpillars produced by the third brood.

Although I haven’t crunched any numbers, so my theory is at best speculative, I have noticed a positive reaction by the Wall to a series of colder winters, starting around 2007/2008.
Prior to the very warm winter of 2006/2007 we had seen a long sequence of winters which were warmer than the 30 year average. 2007/2008 was ‘intermediate’, but the winter of 2008/2009 was the coldest (in the UK) since 96/97, 2009/2010 was the coldest since 78/79, 2010/2011 was the second coldest since 85/86, and 2012/2013 was 0.4 deg. below the 30 year average, with cold spells in early December, mid-late January and late February. The exception to this trend was the winter of 2011/2012, which was much milder than the previous three winters, and more in line with the preceding warm sequence.

A look at just one set of data - the numbers of Wall seen on Nigel Kemp’s High and Over (Seaford) transect - is interesting. These are total, annual figures, rather than spring brood numbers, and hence much more research and analysis is required. However, the species has demonstrated a significant (at least local) resurgence since 2008, with a doubling of numbers by 2009 and 2010. I don’t have figures for the last few years, but I’m pretty sure that there has been a further increase. I suspect that this data reflects a similar trend across Sussex.

This recent rallying in Wall numbers is certainly in line with my own observations elsewhere in Sussex. The Sussex sightings database also demonstrates that the Wall has started to appear more widely in Sussex over this period, with a movement northwards across the Weald and a westward spread along the Downs.

It would appear that the recent sequence of colder winters has been advantageous to the Wall, and I therefore suspect that warmer, more humid winters are disadvantageous to the over-wintering caterpillar. It may well be that these disadvantageous conditions are disproportionately unsuitable for the smaller caterpillars produced by third brood adults.

I will further speculate as to why this might be. Perhaps the most obvious candidate is mould. Could it be that the smaller caterpillars produced by third brood butterflies are more prone to be being killed by mould? This might itself be a function of the behaviour of caterpillars during warm spells within the period of diapause. Are smaller caterpillars more likely to become active during warmer periods, as they attempt to continue their development? This might increase their chance of picking up moulds or pathogens. It might also make them more susceptible to predation.

So the decline of the Wall might possibly be due to a combination of factors associated with climate change, including a thermally influenced trend for the more regular production of third broods, and a higher rate of mortality in the small, third brood caterpillars when a warm, more humid winter follows. The more advantageous, colder winters may become even rarer as the UK moves further away from a continental type climate, potentially exacerbating the decline.

Although an extended autumn might provide a longer period for the third brood caterpillars to grow in preparation for diapause, it would probably take a very significant extension of warm autumn weather before they could ‘catch up’ with the caterpillars of second brood butterflies, which may be much better equipped to face winter at present. To me, it seems that the Wall may be in trouble (at least in the South) for a while yet, unless we see a continuation of harder, colder winters, which seems unlikely.

BWs, Neil

[peterc]

Very good argument you put across there Neil.

Good to hear that populations are increasing in Sussex even if 2011 and 2012 had relatively poor summers and consequently butterflies generally suffered big declines. It would be interesting to know how much of the annual increase for the Wall in the last few years is attributed to the third brood. Maybe counts of just the spring brood will help determine the impact of any unfavourable conditions during the preceding winter.

I look forward to reading more about this topic.

Peter

[badgerbob]

Hi Peter. Although I do not have records of winter weather since 2008/9 I do have counts of 1st brood Wall Brown on my regular circuit!! As mentioned on my previous post the 3rd brood numbers in all these years were insignificant. I would point out that a wet summer can be beneficial for this species as the grasses the larva eat is more lush, as it is with many of the 'Brown' species.
Just a reminder that my circuit is roughly a 4 miles round trip with 4 strong colonies although Wall can be seen almost the whole length of the walk. Unfortunately I didn't manage a count in 2014 on the first brood due to home commitments and weather being poor on the days I would have been free. However, on a North facing colony nearby I did get a count of 69 which was a 1st brood record for this particular site.

These counts are for my normal regular circuit.

2009 39
2010 20
2011 12
2012 31
2013 60

If there is any substance to the 3rd brood theory next year could well show it up with such a large 3rd brood this year.

I hope these records are of some interest.

Bob.

[Neil Hulme]

Hi Bob,

Thanks for providing those figures. As you say, it will be very interesting to see what happens this coming spring. After such large third broods on your patch in East Sussex, and at Mill Hill in West Sussex (and particularly if we continue with the mild winter conditions we have seen to date), I would expect to see a serious slump in the 2015 first brood.

It will be particularly interesting to compare spring performance with the Steyning Downland Scheme site, which produced an excellent second brood, but not a sniff of a third.

BWs, Neil