Fritillaries for a Future.

[PhilBJohnson]

"A dog violet (Viola riviniana) wood"
is possibly superficially, aesthetically less pleasing than "a bluebell wood" or a “Wood Anemone Forest”, but many of our native Fritillary Butterfly Species have relied on Dog violet woods in the past.
Because of their decline and now better management practices, Fritillaries could have a better future in the United Kingdom.
Such threatened species included:
Silver-washed Fritillary
Dark Green Fritillary
High Brown Fritillary
Small Pearl-boadered Fritillary
Pearl-boadered Fritillary
The way some of these butterfly species dispersed their eggs, so that the caterpillars then go and find their specific food source, rather than a butterfly laying directly onto a leaf, suggested to me, that they evolved in places where Viola riviniana (caterpillar food plant) was locally more prolific or numerous (a bit like a bluebell wood might be in certain specific locations).

Thanks to some of the National Trust's work, recognising and understanding the importance of our native woodland heritage, our largest native Fritillary (the Silver-washed fritillary) was a resident species at Bookham Common."

[PhilBJohnson]

Paradise Almost Lost.
Propagation of Viiola riviniana found on ancient sites (varieties or strains of vigorous, leafy plants for caterpillars), was going to be fundamentally important for expansion of UK Fritillary species distribution ranges and connecting sites with suitable habitat, in a better future for UK butterflies.
Almost one tenth of our United Kingdom resident butterfly species used the Common Dog Violet as their primary food source for their larva.
One needed to remember that it was illegal to uproot native wild flowers without permission from a land owner.

Ancient native varieties (or strains) of the "Common" Dog violet needed to be identified (those that had evolved with our Fritillary species) in sun or shade loving habitats and plant samples kept for propagation.
Hand picked hybrids for bigger more colourful flowers, need to be considered unacceptable, as also those that had been specifically hybridised (crossed) for fragrance.
One identified specific plants that adult butterflies chose to egg lay on, so kept for propagational reasons. Propagation needed to be done on a big scale and plants grown on under ideal growing conditions (farming) to help the butterflies connect between different suitable habitats in a better replanted future.
This needed to work "hand in hand" with better habitat management.
A Conclusion
Historically, in a deciduous woodland where plants (flora) competed for light space on the ground, over management for a Spring flower show (aesthetically pleasing flowers) with other floral species had taken place, previously without a knowledgable, better informed, educated understanding of other wildlife needs.

[PhilBJohnson]

November/December Habitat Management
Deciduous Woodland Violets
“As i thought, violets did not detract to a bulb in winter like bluebells and kept in leaf, unlike Wood Anemone, it was thought that a light, less damaging woodland dead leaf rake in November or December, might help keep violet growth more vigorous in glorious winter daylight, with a forward thought of maintaining more violets in a better future for fritillaries.
Does anyone have more thoughts about this, for me please?

[NickMorgan]

I am lucky to have some woodland where I have been playing about, trying to enhance it all primarily for butterflies. I have a few small scale projects on the go in an attempt to learn a bit more about better management. The biggest lesson I have learned is that there is no perfect solution. Wildlife requires a mosaic of habitats, and what we do to improve an area for one species may ruin it for many others.
The woodland used to be completely unmanaged, so was very overgrown with rhododendron and sycamore. Any spaces there were, tended to be overgrown with rose bay willow herb and nettles.
So, top priority is removing rhododendron, which is a slow laborious task. I am trying to not use herbicide, but have experimented a bit with it. The best method appears to be hard labour, though!
Anyway, on one bank where I removed several sycamore trees I noticed that dog violets were quick to (re)colonise. However, over time grasses have taken hold, but the violets are still there.
I cut and lift the vegetation in this small area, so it is short when the leaves fall. Therefore, the leaves tend not to gather there, but are blown away.
I have noted that there are a lot of Dark Green and Small Pearl-bordered Fritillaries in the valley above our house. They all tend to be in more open habitat and the violets are holding their own for now. However, the valley used to be grazed, but has been bought by a landowner who has planted trees and left open areas. My fear is that the wild flowers in the open areas will become swamped by grasses, heather and bracken in the future.
So, I think for violets to be successful there may need to be a bit of grazing or tree cover. I think that it wouldn’t take much leaf litter to swamp them, though, so I would be inclined to rake leaves off areas of violets.

[bugboy]

Surely the one thing with raking up leaf litter is that you are also raking up the Fritillary caterpillars (not to mention countless other invertebrate life)?

[NickMorgan]

Surely the one thing with raking up leaf litter is that you are also raking up the Fritillary caterpillars (not to mention countless other invertebrate life)?

It is very difficult to find the best solution and it will always be a compromise. As I said above, making a habitat for one species will ruin it for other species. In this situation it will be a case of assessing if the leaf cover is likely to smother the violets. if that is the case then the leaves should be raked off, as any fritillary caterpillars will die without their food source. The leaves can be left in piles close by, so any invertebrates can still used them for shelter, or can return to the violets.
Every time I cut a bit of meadow I am conscious about the shelter I will be removing for other creatures, or the possibility of caterpillars and chrysalises being among the vegetation I am cutting.
Sadly, because we have less and less natural habitat, we have to manage what we have. It is a case of trying to find the best compromise and making sure that a mosaic of habitats are created to provide for as wide a range of fauna and flora as possible.

[PhilBJohnson]

Sadly, because we have less and less natural habitat, we have to manage what we have. It is a case of trying to find the best compromise and making sure that a mosaic of habitats are created to provide for as wide a range of fauna and flora as possible.

I think I agree Nick, that if management is for wildlife diversity, then a habitat can be of more interest and precious for a wider group of people, particularly when important habitat areas have been limited to small spaces.
I have seen some historical quotes of woods with many more fritillary butterflies and noted some "loose links" to traditional coppice practice which might no longer occur. More Viola riviniana (larval food plants, violets) should mean more fritillary numbers restored in our woods. A small flower with not much fragrance does not always impress some people but the resulting butterflies, which can help give people a sense of wellbeing, are more likely to.
I thought there was a historical management argument for many woods, to help this plant become more numerous.
In some of our "Lincolnshire Limewoods" (where mature Oak trees had been felled for need in a succession of World Wars), the Silver-washed Fritillary (SWF) had returned, where it appeared to have been absent for a long time.
I read recently (Life Cycles of British and Irish Butterflies, page 200) that the SWF larva only find violets to feed on in the Spring, after over-wintering in a bark crevice 1 or 2m above ground level. Raking in an autumn or early winter, when and where violets might be completely dead leaf covered, might not rake up any, or many SWF caterpillars.
I am not asking that entire woods should be dead leaf raked each year, but I am wanting to see woodland violets become more numerous again and I was exploring what might be a best practice to achieve that, in a future.
"On another other hand" in a previous cooler climate era in the United Kingdom (or in Sweden), violets had survived for long winter periods under snow (there might not be much snow under an Oak canopy).

kind regards

[PhilBJohnson]

Pearl-bordered Fritillary Habitat
In Pete's book, he mentions that the butterfly species required:
"a good amount of leaf litter that creates the required microclimatic conditions for the successful development for the immature stages"
Ref: Page 186, Life Cycles of British and Irish Butterflies - 2019 Peter Eeles
so,
the final Instar larva hibernates amongst dead vegetation after feeding on violates, late summer.

Silver-Washed Fritillary (SWF) Habitat
the tiny 1st Instar Larva over-winters in a bark crevice and feeds on violets the following Spring.
In Pete's book he says:
"Ash & Beech Woodlands appearing unsuitable"
P198, Life Cycles of British and Irish Butterflies - 2019 Peter Eeles
so,
I thought that in Lincolnshire, where recently the SWF butterfly had re-appeared after about a 70 year absence, it could have been related to the maturity of Oak Trees and the 1st instar larva being able to find a suitable crevice (Ash and Beech had quite smooth bark in comparison with older Oaks). SWF predation rates of tiny first instar, over-wintering larva might have been higher when eggs were laid on other tree species.
Many Lincolnshire Woods were clear felled during war time for immediate economic reasons, leaving some of our oldest Oaks on boundaries where ownership might have been contested.
In a future, where Oak Wood timber was needed (Forestry England), it was thought that canopy Oak pollarding might still leave a suitable habitat for the female SWF to lay eggs lower down on the shady side of an old, large, living, creviced Oak trunk.
It was also thought that an old pollarded Oak would likely suffer less storm damage, thus live longer without tree bough supports (for example, unlike "The Major Oak" in Nottinghamshire).
Some violets at Southrey Wood, Lincolnshire, were seen on a shady bank, where dead leaves did not appear to have collected at a light blocking depth, for a long period of time.

An Oak left as a "standard tree" in amongst a 12 year coppice rotation at Southrey Wood, Lincolnshire. This part of the wood was managed by Butterfly Conservation, for the Forestry Commission.

January 19th 2020. Some ground flora near the above Oak, possibly included Violets & Celandine

[PhilBJohnson]

These were believed to have been Sweet violets, flowering on 21st March 2020 in Lincolnshire. They were thought to achieve a maximum leaf energy growth, just before flowering, so root dividing Sweet violets in February and replanting them correctly in the ideal light/space with other flora, had them flowering again later in March in smaller groups for future clump forming.

Violet flowering March 21st

These different Violets, shown below, were believed to be Common Dog Violets (countrywide, not so common as they were), were flowering on 22nd April in Lincolnshire, after the others (above) had finished flowering. Dog Violets appeared to have preferred (or been more tolerant) of shade, flowering before other ground flora canopy encroached, and deciduous trees leafed.

Violets flowering April 22nd

A study of violet flowering times (helpful for species identification), was also helpful for understanding maximum leaf growth periods in time with Fritillary larval appearances, in autumn and after over-wintering in the Spring.

[PhilBJohnson]

How do our native violets that liked shade, cope with autumnal leaf fall and or layers of snow, being in perennial leaf, low on the woodland ground? 

My visit to Sweden in 2017, where site specifically, there were many species of Fritillary, also had more winter snow than in the United Kingdom.
Colder winters, less woodland caterpillar eating birds?
Perennial, always in leaf Violet leaves (Lincolnshire, UK winter 2022), might have feed provided, Fritillary butterfly larvae, with a degree of winter anti-freeze?
#Native Violets
#Lessar Celandine & # Wood Anemonie might have flourished more from early winter coppice, because of possible, no, or less leaf trample, to do with seasonal specifics. It was thought Anemone & Celandine, (pretty Spring flowers in competing Spring light space),might not have life cycled woodland butterflies at larval stage.
#LeafMulch #WinterCoppice #SeedingNativeViolets #Plugging Native violets #Native Florae Provenance (Local wild, native provenance).
#Viola hybrids (generationally grown for floral garden, not wanted in some wild spaces, because of no or less, important slow evolutionary relationship between flora and insect butterfly fauna).