Benjamin
Re: Benjamin
Really enjoying your posts Ben - lot of time/work gone into them. You certainly found yourself 'a project'. Careful how much you disclose - you don't want the place crawling with collectors.
Re: Benjamin
Glad you enjoyed the video Jon and David. It will always be niche but if you’re interested in understanding/showing the wider context then there can be little better - the technique may have a wider appeal when the subject is an Emperor on territory at the top of an oak tree, or a pupa hidden away half way up a sallow - I’d better get practicing.
The discrepancy in leafing time certainly creates a big gap between larval development initially, but this gap closes somewhat as the late starters complete more of their development in warmer conditions so tend to rattle through the instars in a way the early starters certainly don’t.
Thanks Pauline - you’re right that I should be careful with exact locations. I’ve been experimenting with hidden trail cams to try to pick up predation - would be interesting to catch someone removing the cats! (These are carefully positioned with only the subject in view so shouldn’t impact on the privacy of others using the woods).
Cheers Wurzel and Trevor - like everything else you get your eye in after a while, so much so that I often miss really obvious things sitting right in front of me when looking for cats - different caterpillars of other shapes and sizes sometimes seem to materialise out of thin air after already searching a branch for several minutes and I wonder how I could have been so blind.
Another check up to see how things have progressed over the last week of sunny days but still cold nights:
Firstly I must report that Hollis Brown has begun to feed - anyone familiar with the Ballad of Hollis Brown will appreciate the significance of this!
Unfortunately, however, Rosemary was nowhere to be seen. I searched extensively hoping that she’d been particularly adventurous in her search for the perfect spot to begin feeding but no luck - I have to conclude that she was picked off a day or two shy of achieving winter survival.
All others were still present and the majority are now feeding, so winter survival can now reasonably be calculated.
Obviously 7 out of the Dylan 20 works out at 35% survival. The wider sample suggests 43% but when this is adjusted in an attempt to account for the fact these ‘extras’ are found throughout the winter (and clearly the likelihood of them surviving grows the later you find them), the number comes back down closer to the 35%.
Last year only 5 of the 20 survived, so survival was lower at 25%. The wider sample was considerably bigger last year, but pleasingly the adjusted survival rate matched that of the 20 very closely, so I do have confidence that these figures represent the wider population.
Interestingly the number of winter survivors in my main study area has been very similar in both years - 14 last year, and 13 this. It might be expected, of course, that the overwintering larvae would be predated down to a certain level, so it’s not surprising to see a larger population suffer greater losses (last year), but with winter survival generally being considered a key indicator of the season to come, it is interesting to see how the relationship between population and survival rate plays out at a given site. If I keep recording a very similar number of winter survivors, regardless of starting population, then it would suggest that the population at my site is being limited by available habitat - if you cram more larvae into the same available space then they just get picked off.
Having said that it’s hard to imagine that the 2-300 sallows that I monitor can only support a little over a dozen caterpillars. But then again many are unsuitable with perhaps only 50 offering good egg laying opportunities, and only the handful that offer optimal conditions being heavily favoured year after year.
As I keep saying, I need a good year to see what happens. Presumably in such a year the tolerance for marginal conditions will increase as density of eggs increases, which will in turn lead to reduced winter survival as marginal conditions take their toll. Or maybe females will just leave to seek out suitable habitat further afield. Certainly plenty to think about as I plod on collecting data.
A few photos to finish - X2 swearing at me from a distance (go on, you can find him), Tiny Montgomery doing an excellent job of melting into the flower sepals (if that’s what they are?), X5 rejecting the sepals and waiting for the real thing (when he gave me the ‘V’ I knew I’d outstayed my welcome), and X3 still leading the field as a result of his position on an early leafing tree.
The discrepancy in leafing time certainly creates a big gap between larval development initially, but this gap closes somewhat as the late starters complete more of their development in warmer conditions so tend to rattle through the instars in a way the early starters certainly don’t.
Thanks Pauline - you’re right that I should be careful with exact locations. I’ve been experimenting with hidden trail cams to try to pick up predation - would be interesting to catch someone removing the cats! (These are carefully positioned with only the subject in view so shouldn’t impact on the privacy of others using the woods).
Cheers Wurzel and Trevor - like everything else you get your eye in after a while, so much so that I often miss really obvious things sitting right in front of me when looking for cats - different caterpillars of other shapes and sizes sometimes seem to materialise out of thin air after already searching a branch for several minutes and I wonder how I could have been so blind.
Another check up to see how things have progressed over the last week of sunny days but still cold nights:
Firstly I must report that Hollis Brown has begun to feed - anyone familiar with the Ballad of Hollis Brown will appreciate the significance of this!
Unfortunately, however, Rosemary was nowhere to be seen. I searched extensively hoping that she’d been particularly adventurous in her search for the perfect spot to begin feeding but no luck - I have to conclude that she was picked off a day or two shy of achieving winter survival.
All others were still present and the majority are now feeding, so winter survival can now reasonably be calculated.
Obviously 7 out of the Dylan 20 works out at 35% survival. The wider sample suggests 43% but when this is adjusted in an attempt to account for the fact these ‘extras’ are found throughout the winter (and clearly the likelihood of them surviving grows the later you find them), the number comes back down closer to the 35%.
Last year only 5 of the 20 survived, so survival was lower at 25%. The wider sample was considerably bigger last year, but pleasingly the adjusted survival rate matched that of the 20 very closely, so I do have confidence that these figures represent the wider population.
Interestingly the number of winter survivors in my main study area has been very similar in both years - 14 last year, and 13 this. It might be expected, of course, that the overwintering larvae would be predated down to a certain level, so it’s not surprising to see a larger population suffer greater losses (last year), but with winter survival generally being considered a key indicator of the season to come, it is interesting to see how the relationship between population and survival rate plays out at a given site. If I keep recording a very similar number of winter survivors, regardless of starting population, then it would suggest that the population at my site is being limited by available habitat - if you cram more larvae into the same available space then they just get picked off.
Having said that it’s hard to imagine that the 2-300 sallows that I monitor can only support a little over a dozen caterpillars. But then again many are unsuitable with perhaps only 50 offering good egg laying opportunities, and only the handful that offer optimal conditions being heavily favoured year after year.
As I keep saying, I need a good year to see what happens. Presumably in such a year the tolerance for marginal conditions will increase as density of eggs increases, which will in turn lead to reduced winter survival as marginal conditions take their toll. Or maybe females will just leave to seek out suitable habitat further afield. Certainly plenty to think about as I plod on collecting data.
A few photos to finish - X2 swearing at me from a distance (go on, you can find him), Tiny Montgomery doing an excellent job of melting into the flower sepals (if that’s what they are?), X5 rejecting the sepals and waiting for the real thing (when he gave me the ‘V’ I knew I’d outstayed my welcome), and X3 still leading the field as a result of his position on an early leafing tree.
- X2 not pleased to see me
- Tiny Montgomery
- X5 pretty pic
- X5 more interesting pic
- X5 making his feelings known
- X3 well ahead
-
Neil Hulme
- Posts: 3595
- Joined: Fri Feb 08, 2008 8:27 pm
Re: Benjamin
Hi Ben
Great reports on the cat progress. I loved your Polish art house film too (I know the location well); the fact that both the narrative and music are in Polish doesn't detract at all.
BWs, Neil
Great reports on the cat progress. I loved your Polish art house film too (I know the location well); the fact that both the narrative and music are in Polish doesn't detract at all.
BWs, Neil
Re: Benjamin
I'm glad Tiny Montgomery is hanging on in there 
He has done a fantastic job of blending in, but not quite as good as X2
Have a goodun and stay safe
Wurzel
He has done a fantastic job of blending in, but not quite as good as X2 Have a goodun and stay safe
Wurzel
Re: Benjamin
Cheers guys -
Just a quick post to show where we are this year compared to last. A rarely used woodland path in the heart of my study zone - taken on 24th April 2020 & 2021.
Just a quick post to show where we are this year compared to last. A rarely used woodland path in the heart of my study zone - taken on 24th April 2020 & 2021.
- 24/4/2020
- 24/4/2021
Re: Benjamin
That really does bring it ('the drought') home!
I guess the last stanza is off-beam, but you get the drift:
Where have all the flowers gone?
Long time passing
Where have all the flowers gone?
Long time ago
Where have all the flowers gone?
Young girls picked them every one
When will they ever learn?
When will they ever learn?
I guess the last stanza is off-beam, but you get the drift:
Where have all the flowers gone?
Long time passing
Where have all the flowers gone?
Long time ago
Where have all the flowers gone?
Young girls picked them every one
When will they ever learn?
When will they ever learn?
Re: Benjamin
That makes a great contrast, Ben. I suspect the cause of such a stark difference is the persistent low temperatures - last April was also sunny and dry, but a great deal warmer. Unfortunately, there is still no real sign of any warm weather in the forecast at the moment.
Cheers,
Dave
Cheers,
Dave
-
Neil Hulme
- Posts: 3595
- Joined: Fri Feb 08, 2008 8:27 pm
Re: Benjamin
Hi Ben
Those pictures paint a thousand words. The combination of cold and drought has even stopped the grass from growing.
BWs, Neil
Those pictures paint a thousand words. The combination of cold and drought has even stopped the grass from growing.
BWs, Neil
Re: Benjamin
Indeed they do. Looks like about 4 weeks' difference between those two images.Neil Hulme wrote: ↑Mon Apr 26, 2021 9:41 pmThose pictures paint a thousand words. The combination of cold and drought has even stopped the grass from growing.
Last year, given how mild February & March were (although rather wet and stormy), the plants were ahead of the butterflies. This year, it's the other way round given the levels of sunshine we've had, with the cold nights suppressing plant growth.
Re: Benjamin
Thanks for the thoughts regarding the cold drought - one of the great benefits of mobile phone cameras is the ability to use the camera roll as a diary - I’d never be organised enough to keep such useful records if it required any more effort than a quick snap.
A quick entry to clarify things (as much for myself as for anyone else’s interest!):
After winter losses and the unfortunate recent loss of the pack leader X3 we have the following remaining:
Lily
Billy The Kid
Mr Clean
Tiny Montgomery
Skinny Moo
Hollis Brown
Corrina
X1
X2
X4
X5
X10
DD 1
As much as it’s disappointing to lose each and every one, it becomes a lot easier to keep a close eye on them when numbers are reduced to this kind of level.
All have now started feeding, with the majority nicely ‘greened’ and looking to begin the L4 chapter imminently. A few are still only just nibbling buds, and a few somewhere in between and settling into the midfield.
In terms of the season ahead much, as ever, will depend on the next 8 weeks of weather, but, if I had to book a week off work to spend observing the flight period then I would gamble on the 2nd week in July (in Sussex at least).
Based on a nascent understanding of my site, I expect a poor season (in terms of numbers) similar to last year, but would be delighted to be wrong - not because I’m desperate to see masses of emperors, but because a great flight season would illuminate just how poorly I understand my site, which would be a rather useful thing to know. Matthew is more hopeful.
Competition for sallow is fierce as always, with the brief window where iris damage is relatively easy to spot rapidly closing. The window exists as a result of the substantial damage the overwintering caterpillars can do to bursting buds/young leaves, while the many moth species that overwinter as eggs (and sawfly overwintering as pupae) take a little while to hatch and grow to a sufficient size to leave a similar trail of destruction. There are other moth species that overwinter as part grown caterpillars, but in a similar way to iris, they are predated heavily over winter and so resume feeding at low density in spring and are not often encountered. Once you see it, iris feeding damage is easily recognisable at all stages anyway, but scanning for it is obviously easier when it’s the only substantial damage present.
I used this window to search out of reach branches (with bins) for a couple of days but found no new larvae.
A quick entry to clarify things (as much for myself as for anyone else’s interest!):
After winter losses and the unfortunate recent loss of the pack leader X3 we have the following remaining:
Lily
Billy The Kid
Mr Clean
Tiny Montgomery
Skinny Moo
Hollis Brown
Corrina
X1
X2
X4
X5
X10
DD 1
As much as it’s disappointing to lose each and every one, it becomes a lot easier to keep a close eye on them when numbers are reduced to this kind of level.
All have now started feeding, with the majority nicely ‘greened’ and looking to begin the L4 chapter imminently. A few are still only just nibbling buds, and a few somewhere in between and settling into the midfield.
In terms of the season ahead much, as ever, will depend on the next 8 weeks of weather, but, if I had to book a week off work to spend observing the flight period then I would gamble on the 2nd week in July (in Sussex at least).
Based on a nascent understanding of my site, I expect a poor season (in terms of numbers) similar to last year, but would be delighted to be wrong - not because I’m desperate to see masses of emperors, but because a great flight season would illuminate just how poorly I understand my site, which would be a rather useful thing to know. Matthew is more hopeful.
Competition for sallow is fierce as always, with the brief window where iris damage is relatively easy to spot rapidly closing. The window exists as a result of the substantial damage the overwintering caterpillars can do to bursting buds/young leaves, while the many moth species that overwinter as eggs (and sawfly overwintering as pupae) take a little while to hatch and grow to a sufficient size to leave a similar trail of destruction. There are other moth species that overwinter as part grown caterpillars, but in a similar way to iris, they are predated heavily over winter and so resume feeding at low density in spring and are not often encountered. Once you see it, iris feeding damage is easily recognisable at all stages anyway, but scanning for it is obviously easier when it’s the only substantial damage present.
I used this window to search out of reach branches (with bins) for a couple of days but found no new larvae.
- Tiny Montgomery
- X2
- DD1
- X10 with company
- The competition isn’t shy
Re: Benjamin
Another wonderful update with clear photos. Thank you for sharing very informative.
Re: Benjamin
Ben I'm in awe of this study/research you have undertaken and appreciative of the level of detail you are sharing. Fascinating stuff!
Re: Benjamin
Crickey Ben - excellent read your PD with the added bonus of your own version of 'Where's Wally' thrown in 
Have a goodun and stay safe
Wurzel
Have a goodun and stay safe
Wurzel
Re: Benjamin
Great continuation, Ben. Things looking a bit more spring-like in those images.
Interesting to read your comments regarding your expectations for the flight season. I guess a lot depends on weather conditions from final instar through to adult emergence.
Interesting to read your comments regarding your expectations for the flight season. I guess a lot depends on weather conditions from final instar through to adult emergence.
Re: Benjamin
Thanks again folks - I’m really glad it’s of interest!
Predictions are a really important part of it for me David, as they’re clearly a good measure of how well you understand the thing you’re studying. Last year I was wrong about the earliest appearance (I thought last few days in May/first few days in June on the basis of the progress of the most advanced caterpillar I was following) but was right about the key weeks being mid-late June.
I learned just how dramatic a difference weather can make (in all stages), with rapid progress completely halted for several days at a time in unfavourable conditions. Key processes (especially ecdysis/pupation) can apparently be delayed without issue until the right conditions return.
Had conditions in May stayed warm and settled then the last few days in May wouldn’t have been out of the question for an early appearance. This photo of the most advanced L5 caterpillar was taken on May 4th. Progress had been so fast up until that point that pupation after another week leaving 2-3 weeks as a pupa seemed perfectly plausible.
As it happened the weather crashed in May and after a return to warmth in late May, crashed again in early June and progress of all the caterpillars under observation slowed dramatically. Having now observed pupation in the wild a number of times, I’m sure that even under favourable conditions the caterpillar pictured would have taken at least another 10 days to pupate, so had he survived, would likely have emerged towards the end of the 1st week in June. Others not under observation, however, must have been even further advanced (especially, I assumed, amongst the mighty population at Knepp) so we may still have been close to a May emergence (had the weather not collapsed).
This year I’m at the other end of the spectrum but probably making the same mistakes and expecting things to be later than others are suggesting. If we ever get any warm weather then I’ll no doubt experience just how fast things can speed up after a slow start, but I have tried to account for that in my predictions (if I’m wrong then it’ll be because I’ve underestimated this effect).
So that’s timing - the other challenge is to predict quality of flight season, or numbers. Last year I didn’t know what to expect, but having searched my site and surrounding areas extensively, I was very intrigued to see where the large numbers that were predicted were going to come from! As it turned out I saw very little in my main site, with other areas, near and far being equally disappointing. Gales in late June/early July no doubt took their toll on the population, but it was very much my feeling that numbers were poor anyway, and this just added to the problem.
So this year I have a very similar post hibernation population (after a smaller pre hibernation population were less heavily predated), so would expect to see a similarly poor flight season. Again, if numbers are high, I’ll wonder where they have come from, but at least I’ll know that I’m missing something and can set about sorting that out.
Currently i can imagine a season with an extended wait for the emergence to begin (nothing until July), promising numbers initially (as the field will have bunched up) but more of a ‘gentle fart’ than a ‘big bang’ in the second week of July and then the usual gradual decline with a few individuals flying late into August or even early September - at which point we can go searching for eggs again.
That’s how it looks at my site anyway. Last year it seemed a good barometer for everywhere else but that might not always be the case, especially for sites in other parts of the country - Fermyn most obviously.
Anyway, that was a fairly long post to pretty much state the obvious, but it does sometimes help to get it down in writing - at least I can look back and see where I went wrong!
Predictions are a really important part of it for me David, as they’re clearly a good measure of how well you understand the thing you’re studying. Last year I was wrong about the earliest appearance (I thought last few days in May/first few days in June on the basis of the progress of the most advanced caterpillar I was following) but was right about the key weeks being mid-late June.
I learned just how dramatic a difference weather can make (in all stages), with rapid progress completely halted for several days at a time in unfavourable conditions. Key processes (especially ecdysis/pupation) can apparently be delayed without issue until the right conditions return.
Had conditions in May stayed warm and settled then the last few days in May wouldn’t have been out of the question for an early appearance. This photo of the most advanced L5 caterpillar was taken on May 4th. Progress had been so fast up until that point that pupation after another week leaving 2-3 weeks as a pupa seemed perfectly plausible.
This year I’m at the other end of the spectrum but probably making the same mistakes and expecting things to be later than others are suggesting. If we ever get any warm weather then I’ll no doubt experience just how fast things can speed up after a slow start, but I have tried to account for that in my predictions (if I’m wrong then it’ll be because I’ve underestimated this effect).
So that’s timing - the other challenge is to predict quality of flight season, or numbers. Last year I didn’t know what to expect, but having searched my site and surrounding areas extensively, I was very intrigued to see where the large numbers that were predicted were going to come from! As it turned out I saw very little in my main site, with other areas, near and far being equally disappointing. Gales in late June/early July no doubt took their toll on the population, but it was very much my feeling that numbers were poor anyway, and this just added to the problem.
So this year I have a very similar post hibernation population (after a smaller pre hibernation population were less heavily predated), so would expect to see a similarly poor flight season. Again, if numbers are high, I’ll wonder where they have come from, but at least I’ll know that I’m missing something and can set about sorting that out.
Currently i can imagine a season with an extended wait for the emergence to begin (nothing until July), promising numbers initially (as the field will have bunched up) but more of a ‘gentle fart’ than a ‘big bang’ in the second week of July and then the usual gradual decline with a few individuals flying late into August or even early September - at which point we can go searching for eggs again.
That’s how it looks at my site anyway. Last year it seemed a good barometer for everywhere else but that might not always be the case, especially for sites in other parts of the country - Fermyn most obviously.
Anyway, that was a fairly long post to pretty much state the obvious, but it does sometimes help to get it down in writing - at least I can look back and see where I went wrong!
Re: Benjamin
Another check on the 13 today and still no L4s. Some have been waiting for several days to transition so I couldn’t understand why the midday sunshine and relative warmth wasn’t enough to spur them on - then it became very dark and the heavens opened. The freezing rain had returned - not a time to be taking your clothes off.
No lovely evening light in the middle of the day, but a couple of pics to show that we are finally looking a bit more spring like.
No lovely evening light in the middle of the day, but a couple of pics to show that we are finally looking a bit more spring like.
- The waiting game.....
-
Padfield
- Administrator
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- Location: Leysin, Switzerland
- Contact:
Re: Benjamin
I can't tell you what a pleasure it is to read your diary, Benjamin.
Guy
Guy
Guy's Butterflies: https://www.guypadfield.com
The Butterflies of Villars-Gryon : https://www.guypadfield.com/villarsgryonbook.html
The Butterflies of Villars-Gryon : https://www.guypadfield.com/villarsgryonbook.html
Re: Benjamin
Me too, Guy. I'm developing the same protective instincts for these cats as I did for your Swiss ones.
I earnestly hope a few make it to adulthood in spite of the flak they have to dodge.
Who'd be a butterfly?
Re: Benjamin
Well that certainly is pleasing to hear, Guy and David. I will do my best to keep in touch with them for as long as possible.....
Yesterday (7th) definitely seemed a better day for stripping off (if you’re a caterpillar), so I stopped off at the Emperor woods on the way back from a day with PBFs at Rewell Wood.
I wanted to confirm the date of skin change if indeed any had taken the plunge. Only one had, as it turned out, with the rest still patiently waiting. As expected it was X1, the new pace setter since X3 unfortunately disappeared a week or two ago.
I found him looking rather lost in his baggy new clothes and thrashing around wildly trying to untangle some fibrous material from his horns. I try not to interfere but after 5 minutes trying to take a photo without disturbing him (very difficult as he’s just above the reach I can safely achieve atop my stepladder, and thus tempts me into trying to gain another few inches by balancing in an entirely unsafe way) I couldn’t stand by any longer and carefully pinched hold of the offending strand allowing him to pull himself clear 1st attempt. I was very pleased to have helped even if the look he shot me seemed to convey an exasperated disbelief that I could be so arrogant as to think that an intervention was required - classic L4 truculence - the teenage phase.
After a little more thrashing, just to be sure, he settled down allowing me a few more shots which came out surprisingly well given my precarious situation. The sunlight breaking through the rapidly clouding sky helped no end.
A worthwhile stop off - first L4 = May 7th.
Last year 1st L4 was April 9th or 10th.
Yesterday (7th) definitely seemed a better day for stripping off (if you’re a caterpillar), so I stopped off at the Emperor woods on the way back from a day with PBFs at Rewell Wood.
I wanted to confirm the date of skin change if indeed any had taken the plunge. Only one had, as it turned out, with the rest still patiently waiting. As expected it was X1, the new pace setter since X3 unfortunately disappeared a week or two ago.
I found him looking rather lost in his baggy new clothes and thrashing around wildly trying to untangle some fibrous material from his horns. I try not to interfere but after 5 minutes trying to take a photo without disturbing him (very difficult as he’s just above the reach I can safely achieve atop my stepladder, and thus tempts me into trying to gain another few inches by balancing in an entirely unsafe way) I couldn’t stand by any longer and carefully pinched hold of the offending strand allowing him to pull himself clear 1st attempt. I was very pleased to have helped even if the look he shot me seemed to convey an exasperated disbelief that I could be so arrogant as to think that an intervention was required - classic L4 truculence - the teenage phase.
After a little more thrashing, just to be sure, he settled down allowing me a few more shots which came out surprisingly well given my precarious situation. The sunlight breaking through the rapidly clouding sky helped no end.
A worthwhile stop off - first L4 = May 7th.
Last year 1st L4 was April 9th or 10th.
- A couple of days ago
- X1 May 7th