Thanks as always for your positivity David.
Friday 21st
![93E35124-DA0F-4AF4-85E2-3DB356CEC586.jpeg (4.42 MiB) Viewed 2356 times Some context](./files/thumb_17917_71a4cded878b8bd22035728801e69a0d)
- Some context
The search for hibernators is now in full swing. As mentioned before I cover an area of roughly one square km and search something like 300 suitable sallows within that zone. Particular attention is paid to certain hot spots within that range, but everything suitable is searched.
Searching a sallow via dangling leaves should only really take 5-10mins. Sometimes less, sometimes more depending on my calculation of the likelihood of finding larvae there. This sounds like rather a lot, but split over 2 or 3 days a week for a couple of months it’s quite manageable. Days are short though, and much extra time is spent either locating caterpillars once a dangle has been confirmed or keeping records updated/taking photos etc, so I allow something like 20 days in the field to properly survey the site.
![7AF9E874-9549-4F62-BE4F-06E8FF78BEF1.jpeg (4.31 MiB) Viewed 2356 times And some more….](./files/thumb_17917_c24c8d7f94104cadd10397092e09a8fd)
- And some more….
Once the survey is completed I only need to gather data on losses, so just 2 or 3 days a month throughout winter are required for site visits, then obviously an intensive period keeping track of them again through spring.
I should just stress that although a thorough survey certainly requires this significant commitment, finding iris cats in hibernation is really not a very difficult task - once you’re in the right place that is, and I suppose that is the really key part. I know my site well enough now to find the 20 most obvious hibernating caterpillars in a single four hour day - it’s searching the extensive peripheral and less productive areas that takes the time.
Dangling leaves and more recently fluorescing pupae make purple emperor early stages really quite straightforward to study - this despite their often extreme low density. I think this is particularly true of the habitat they generally utilise in the UK, as the relatively small, isolated blocks of suitable woodland often containing ride structures that funnel egg laying females to accessible sallows seem custom made to concentrate early stages in areas conducive to study. Another way of putting that is that in these environments female PE’s are forced to lay their eggs at head height (on average) on occasional sallows that occur along our woodland pathways! What more could you ask for?!!
In my study area of one square kilometre I can be very confident I have a good appreciation of what’s where, and from December onwards I’m ‘in touch’ with most of the individuals residing there - imagine trying to do that with any other butterfly species in the same area!!!
As much as I take pleasure in the genuinely excellent hyperbole and seductive imagery that surrounds this insect - the spurning of scientific intrusion, royalty on high looking down on us with utter contempt for our feeble fumblings etc etc - I actually think it might just be the easiest uk species to study - certainly in terms of an absolute study of immature stages residing within these artificially created isolated or semi-isolated colonies. And that’s the point I suppose - send me to Białowieża Forest to get to grips with iris ecology and I’d learn very little in a lifetime, but let me choose a nice block of isolated woodland here in the UK, and I’ll draw you a detailed family tree after a couple of years.
Ok - a bit of an exaggeration, but the unique characteristics of the PE immature stages (creation of dangling leaves pre hibernation and fluorescing pupae) combined with the artificially imposed (by our fragmented landscape) colonial structures that we find in the UK, enable this species to be studied in a way that no other UK butterfly species could be. My site is not perfect in this regard, as although it is somewhat isolated, there are blocks of woodland close enough to promote a fair degree of movement around the wider landscape. Other sites containing PE colonies are totally isolated with hectare upon hectare of inhospitable farmland surrounding them - these sites particularly enable an absolute study of numbers - EVERYTHING within the colony. Even in these simplified environments, the adult butterfly is hard to pin down, and hence the hyperbole, but if we know exactly how many pupae hatched, then we needn’t spend too much time trying to make assessments based on that which we can only really glimpse.
It’s true I’d be more interested to learn about iris ecology in a vast European forest, but investigating how iris exploits our curious modern landscape is interesting in itself.
Of course not all PE sites in the UK fit this description. Vast rewilding projects (eg Knepp) or tree planting projects (eg Heart of England Forest) can host impressive PE populations at a density or over an area too great for this kind of study. Rewilding projects particularly have the potential to give rise to huge population explosions, in the early phase at least, making the normally elusive adults extraordinary easy to observe. Again much has been, and can still be learned about PE behaviour under these conditions, but just as behaviour in captivity must be appreciated as such, I think we should be careful to keep these observations in context.
Anyway - what was that all about?! Winter ramblings. No doubt I’ll have changed my mind again by the end of winter.
So far I have around 40 caterpillars under observation - the vast majority of which are settled in hibernation. Perhaps 10% are still on their leaves - the latest I’ve seen still wandering about was AJ back in 2019 - still active on the 27th November.
Last year they settled a little earlier, this year a little later, but not by much. The incoming cold weather I keep hearing about should give the final few the hurry up they need.
40 this early is promising in terms of numbers, but I’ve searched the easy, productive areas already, so further additions will be increasingly hard work. It is already better than last year though and hopefully I’ll end up with more than the 50 or so from 2019, making this the best year of the 3 so far - we’ll see.
My overwintering data for the select 20 starts from Dec 1st so I haven’t named too many for fear of losing some of my favourite Olympians before they’ve even started. I do already have a few though and I can’t wait any longer to add one more to the stable. What a specimen this one is - for me it has to be Linford Christie. I seem to remember him complaining about references to his impressive ‘lunchbox’. I was only young at the time but even then I remember thinking that I wouldn’t mind if, in later life, I had to deal with this particular issue - as it turned out I never did (because I didn’t become a Lycra wearing sprinter on TV I should clarify - no other reason - none at all).
![A33380C3-06E8-4674-8AD7-C48BF674DF76.jpeg (1010.34 KiB) Viewed 2356 times Linford](./files/thumb_17917_899c9d00b76a487ef8b78c985375600e)
- Linford
Just to clarify the overwintering rules Linford, you can start whenever you like, and there are no banned substances - you’ll be fine. Oh - but it is a marathon and not a sprint - not to worry - small detail. Welcome, and good luck.