Vagrant - Favourite Photo of 2023

[Wurzel]

Vagrant - Favourite Photo of 2023

Week 20

This is the spot to place those unusual species that turn up from time to time. It used to be the favoured haunt of the Long-tailed Blue but that seems to have earnt its place as a regular visitor and so now has its own spot. Who knows what will start appearing in this thread in coming years but for now Black-veined White springs to mind…

As in previous years details of locations, dates, times and circumstances would be welcome as would any accompanying stories and anecdotes or other observations of behaviour and interesting other points.
Have a goodun

Wurzel

[bugboy]

Ok so this particular butterfly has already made into it's own species thread, but since ssp gorganus still qualifies as a vagrant, it gets a second shot!

[MrSp0ck]

Black-Veined Whites.

A lot of visitors at Hutchinsons Bank last May/June, for the Surprise turnup of Black-Veined Whites, which were hatching on Site, and this winter i found some of Winter 2022/23 hibernation webs, which makes it look like offspring of a migrant female in 2022 when all the othe rmigrants were coming into UK, like th Queen of Spain and Long Tailed Blues. Many accused it of being an introduction but it looks like it was a natural event, and many who thought otherwise missed out on one of the biggest butterfly events in 100 years. Even BC have rowed back on their initial statement after LWT and other researched into it further.

Here are a few of my images

[millerd]

Black-Veined Whites.

...this winter i found some of Winter 2022/23 hibernation webs, which makes it look like offspring of a migrant female in 2022... ...Even BC have rowed back on their initial statement after LWT and other researched into it further...

That's good to hear, Martin. Do you have any shots of those webs so that we have an idea of what we should be looking for in the future? (Hopefully this will not be a one-off event! )

Here is a shot from one of the days they were flying (almost certainly being taken in one of your photos above in fact).

Dave

[Allan.W.]

Good to see shots of Black-Veined Whites once again flying in the UK after an absence of some hundred years plus ,and some excellent shots .Would very much like to see a few shots of the old larval webs .............presumably laid on growing ,fixed branches ,be interesting to see. Personally i have no strong feelings either way ie; from a lone (or a few ) gravid females or artificially introduced .
But one thing that does strike me as odd ,(and i think that this point may have been made before) This particular female must have flown across many miles from presumably France ,and across many acres of suitable habitat ,with masses of Hawthorn /Blackthorn to choose from ,but ended up ..........what 50-60 miles from the French Coast to settle down and lay .
At around the same time i believe that at least one (possibly more ) were seen in the St.Margarets bay area in Kent .I had one possible (and i say possible ) encounter there on the same day that i saw a couple of "Gorganus " Swallowtails .A very "Large " White that patrolled up and down the massed Hawthorn hedgerow, but totally refused to settle or even allow close approach . To me the St.Margarets specimen (s) would be more likely as a possible migrant . All this having been said ,i have always been under the impression that they were a Sedentary species.
Allan.W.

[MrSp0ck]

Hutchinsons Bank always has the migrants fly though about a week after they are on the South Coast, happens with Clouded Yellows, Gorganus Swllowtails and others. It is quite possible that a 2022 female passed through un noticed and laid eggs on a site full of foodplants, we have most of theirs on site too, at least 6 of their listed foodplants.

I will post pictures of the old webs, i need to relocate one but here is a picture of a BVW web note the leaf stalks thet come out the side.

and this is the one on hutch that is now 20 Months old of course. Just below the Hawthorn and Blackthorn bushes about 4ft above the ground, the frass can be seen in the web too the BVW hibernation web top pic is a current one for May/June Butterflies to show what a live web looks like.

[MrSp0ck]

Remember the Hutch web has been through 2 winters and a summer now, so will show some wear.

[Allan.W.]

The first picture is interesting . I do wonder if BVW has been noted as being a migrant to the UK before as i,ve already mentioned i thought that it was known to be a Sedentary species and not wandering too far from its "home turf"
It will be interesting indeed to see what occurs at Hutchinsons Bank this coming season.

[bugboy]

So in regard to the BVW I feel there does need to be an interjection of some common sense and proper analysis of what scant facts are surrounding their provenance. As I see it there is just one fact that we can all agree on, a number of adults emerged on Hutchinson’s Bank, after that it becomes largely speculation with various opinions arising of which I personally have no issue with. What I do find somewhat irksome is when ‘facts’ are invented to push a certain hypothesis and opinions. All we can rely on is knowledge of the species behaviour and ecology to give us some clues as to the likelihood of one opinion or other.

Firstly, BVW aren’t naturally migratory, they are generally considered as living in metapopulations with periodic boom and bust populations and resulting irruptions. Some have been recorded as traveling over 3’000 miles, but this is an exception rather than a rule, a few hundred miles is more normal. Therefore, we can’t rule out a natural occurrence however, any comparisons to true migrants such as Clouded Yellow and LTB is largely inaccurate. It’s more accurate to use something like the QoS Frit as a comparison and last year we saw an incursion. A few individuals were found inland but the vast majority were much nearer the coast. I don’t recall any BVW sightings being recorded in 2022 as this comparison would indicate.
So that’s 1 point in favour of natural and 1 point against.

Now Its been quoted to me that there are over 400 shed skins in the webbings currently found. If that equates to 400 larvae, we are likely looking at multiple females (on average a female will lay 250 eggs). 1 female randomly turning up that far inland is unusual but multiple….
Another point against them being natural.

Unfortunately, Hutchinson’s bank reputation precedes it with many species turning up, some announced, many not so I’m afraid that’s another point against.

Now there’s also, the quite frankly ludicrous, argument that because hundreds have now been found and you can only buy them in small batches that that somehow rules out a release. Its difficult to know where to begin to refute this, the counter argument being so blindingly obvious (unless there’s some unilateral law forbidding multiple purchases, or rearing them at home for a generation or two until you have suitable numbers). In any case the more that are found, the more females would be needed to produce these quantities which points a very big finger to persons unknown.

Based on all that, my opinion is rather obvious and no secret. If more proper evidence, as opposed to random speculation and statements, comes to light I’m more than happy to change it, I for one would love it to be a genuine naturally occurring event, at the moment though I don't.

[MrSp0ck]

2 x 250 = 500 so 400 in 2 webs is within that range

[MrSp0ck]

There are only a few Introductions at Hutch not as many as people say. 2 of which look like are from official BC people

Glanville was put there by the County Recorder and a BC council Member in 2010/2011
Marsh was by the Marsh Dumper in Lockdown, it looks like the Marsh orriginated in Hampshire from that re-introduction.
Dukes were part of BCs Brilliant Butterflies project where the Peoples Postcode Lottery wanted a re-introduction as part of the £1,000,000 funding

thats it.

The last unnoficial introduction was 1983 before these.

So like most reputations its mostly hearsay and not true.

[David M]

2 x 250 = 500 so 400 in 2 webs is within that range

Accepted, but a mere 20% mortality rate during the ovum stage does not tally with natural phenology.

It is argued that at each stage of development, mortality is around 80%, which makes sense as if an average female lays 250 fertilised eggs then that roughly equates to 2 adults emerging from the pupa which keeps the population at largely the same number.

[Pete Eeles]

I completely agree, Paul. Being objective and taking into account the facts and the species’ ecology, then the only conclusion I can come to is that the original sightings are of a release. I’m surprised anyone can possibly think anything else to be honest! How does a non-migratory butterfly end up at Hutchinson’s Bank under its own steam?

It’s a shame that others jumped on the bandwagon, resulting in ridiculous claims being made in the national press, requiring BC to publicly refute these, a position that is upheld on their website: https://butterfly-conservation.org/news ... -butterfly

With at least two coordinated releases in the offing, it will be interesting to see what happens next, and at HB. Perhaps the climate is now suitable for this species, and it would be good to see it back.

Cheers,

- Pete

[MrSp0ck]

If non-migratory explain the one in Dover last year, it has crossed the channel. The Max count also was 4 males and 2 females, so the mortality rate would be the number seen. Ive had an open mind all the time, and the timing off the Knepp re-introduction funding submission a few days after the June Sightings at HB was also interesting was HB a pilot for that, we know they were hatching on site seen drying their wings.

They do migrate in Europe, after a couple of weeks they seem to move onwads.

[Pete Eeles]

If non-migratory explain the one in Dover last year, it has crossed the channel.

1. Release.
2. Assisted travel.
3. A vagrant (a stray, wandering individual).

None of these mean that the BVW migrates.

Cheers,

- Pete