The Great
Butterfly Project
The Ambitious Project
A new and exciting project is well
underway within the woods of Holt
Country Park this winter, aptly named the
Great Butterfly Project, which reflects both
its ambitious nature and target.
Silver Washed Fritillary - History and Life
Cycle
Many of you may have been lucky enough
to witness the Silver Washed Fritillary
on the wing last July and August, a truly
magnificent large orange butterfly with
Glades created Winter 2013, Result in Spring
2014
Glades created Winter 2013, Result in Spring
The long term goal is to further increase
the population of the regionally scarce
Silver Washed Fritillary Butterfly, to
encourage its spread and eventual
dispersal to other suitable habitats across
Norfolk.
The management techniques, (explained
later) used to achieve this goal will
also have large, positive influences on
other resident butterfly species as well
as wildflowers, bees, birds and Great
Crested Newts.
And as always, we hope to enhance
the natural beauty of the woodlands
improving the experience for our visitors.
silver
washed streaks on its under wings giving
it its iconic name, as well as being the
second biggest fritillary in Europe.
Once widespread across England, it
has suffered severe declines in the 20th
century
and was lost from Scotland, Northern and
Eastern England by the 1970s. These
declines are linked to the neglect and
decline of ancient woodland management
systems like coppicing. By coppicing
and tree thinning, light can penetrate
through the trees canopy allowing nectar
rich flowers like Bramble and Common
Knapweed to flourish, in turn providing
a food source for the adult butterflies
enabling them to complete their life cycle.
Part of that life cycle involves the hatching
of caterpillars in late summer after two
weeks spent as an egg deposited under
the bark of an oak or birch tree. After
hatching, the caterpillars hibernate in
a silk pad woven under the bark of the
same tree. Come the spring, they find
their way down from the tree to scent out
Silver Washed Fritillary.
its food plant, Common Dog Violets, and
only Common Dog Violets, fussy eaters!
Many butterfly and moth species are very
specialist with their larval food plants,
another reason why neglect or incorrect
management can lead to localised
extinctions. Once the caterpillars are of
the correct weight, they climb back onto
a nearby shrub to pupate for two to three
weeks before emerging as an adult.
Four years ago Silver Washed Fritillaries
surged north Norfolk during a great
breeding year and four to six specimens
became isolated at Holt Country Park. It
was presumed they would disappear, but
no, they bred and have appeared every
year since. Work has been undertaken
each year to increase this fragile colony,
and indeed numbers have increased
significantly with an approximate 60
individuals on the wing during the summer
of 2014.
But now it is time to step it up. With
a viable population isolated in the lighter
north east corner of the woods where
much of the coppicing, ride management
and glade creation has been undertaken,
we must now encourage a further
population boom and provide them with
the habitat to expand their range
throughout the whole woodland
and beyond.
Elsewhere in England they
have made a come back, with
small, scattered colonies, fragile
and open to localised extinction
if their populations do not
increase to a more sustainable
level.
The Great Butterfly Projects
Management Objectives
In order to allow the spread and
growth of the Silver Washed
Fritillary population as well as
other butterfly species, the creation of
a flower rich, light, twisting, structured
ride has been designed along an existing
pathway within Holt Country Park.
Although it may seem unseasonable to
Holt Daycare, guided by NNDC Ranger Martin
Hope with helping to clear trees along the ride.
be talking about butterflies, especially now
the frosts have started to creep in and
much of our insects have seemingly
disappeared, it is in fact the perfect
time of year to undertake much of the
necessary work. Importantly, birds
have finished nesting so they will not
be disturbed or affected. Reptiles and
amphibians will be hibernating in warm
safe places well away from regularly
walked paths so they will also not be
disturbed or harmed. However, to be
completely sure no wildlife is at risk from
any proposed work, surveys are carefully
carried out beforehand, checking it is
clear and safe to start.
There are many management
techniques needed to achieve our goal
starting with the opening of the existing
tree canopy along the ride to allow the
sun’s rays to reach the ground. As ever,
the aim is to keep everything looking as
natural as possible, so this will be done
in a sympathetic way, not a motorway
ripping through the heart of the woods
but a complex mix of glades, openings
and light traps.
The targeted trees will be the Scots Pine,
not indigenous to this part of England and
with limited wildlife value. Many of the
Beech trees along the proposed ride will
be left to break the openings
Clearing the shade casting Pine Trees, creating
habitat piles with logs and brash.2014
up, preventing a wind tunnel effect and
importantly providing food and a home
for much wildlife. At this time of year you
may be lucky to see or hear Bramblings, a
bird related to Finches that often feeds on
Glade management. Raking off cut grass with
Holt Daycare to reduce nutrient levels.
Beech masts.
Much of the wood sourced from the
felled pines will be given back to nature,
stacked deep within the wood where
it can rot and break down, providing
homes for important invertebrates as well
as hibernation places for Great Crested
Newts. Amazingly, newts can travel more
than 500 metres over the summer away
from a pond in search of moist damp
places full of invertebrates to feed
on, and eventual hibernation sites.
Other non-indigenous trees like
Sycamore regeneration and Sweet
Chestnut will also be cleared in
places. The Holt Day Centre, who
volunteer their much appreciated
services every Monday afternoon
and Wednesday morning as part
of the Muddy Boots club, have
done an exceptional job so far of
cutting away some of the invasive
scrub and sycamore, as well as the
ever problematic Rhododendron.
We, the Rangers, certainly owe them a
massive thank you for all their hard work.
Once the tree canopy has been opened,
it is important to plant back
native shrubs, which will serve
many purposes. Being shrubs
they will never gain the height of
a tree, therefore not shading out
the sun. A good mix of shrubs
adds diversity and structure
to a ride, providing eventual
nesting habitats for a range
of birds as well as a vital food
source for them. Many of our
volunteers understand that they
need to leave and look after
the hawthorns and hollies. A
predator will not be too keen to climb
through the thorns and prickles to get
at nesting birds. A personal favourite
of mine is the Spindle, its characteristic
green stems and pinkish berries make it
a great sight in the autumn. But shrubs
like Alder Buckthorn, the food plant of the
Brimstone butterfly caterpillars will also be
planted, alongside Hazels, Crab Apples,
Wild Pear and Cherry. As always, the
unfortunate part is awaiting
the growth of these plants over the next
few years, but their eventual presence will
be a breath taking mix of spring blossoms
followed by a rich harvest of autumn fruits.
The final question to this project is,
will nature respond? With previous ride
management I have always been amazed
at the wildflower diversity that has risen
from the seed bank after the clearings.
This summer the glades were awash
with Red Campian, Common Knapweed,
Thistles and Ragwort, but also more
unusual species like Common Century,
Agrimony and Fleabane. But to give it
all a helping hand, small pockets will be
seeded with woodland specialist flowers
like Foxgloves, great for the bees, and of
course plenty of Wild Dog Violets.
Rare colour variant of Silver Washed Fritillary
called a Valesina.
Biodiversity and Disturbance
Within the initial fazes of wildlife
conservation, whether it is restoring
woodland from plantation to native
broadleaved trees, turning a field into a
flower rich meadow, or preventing reed
beds becoming overtaken by spreading
willow, there is always some degree of
disturbance through the management
techniques. However, getting the level
of disturbance right is vital to achieve
maximised species diversity.
Mass disturbance within any habitat
can have a serious, negative impact on
the resident wildlife. For example, to
completely clear woodland of all its trees
in order to plant a different mix of wildlife
friendly trees may sound a good idea on
paper if what was there was degraded
plantation, but there is always something
living there, existing communities that
need the time to adapt or move. To clear
fell would be incredibly damaging to the
wildlife and the environment. Furthermore
a clear fell allows sudden differences
in the exposure to the climate. Being
opened up to the elements can lead to
soil erosion through heavy rainfall and
flash flooding washing nutrients from the
topsoil away. Exposure to sunlight also
allows vigorous
plants like bracken to smother the ground,
out competing trees and wild flowers,
slowing the regeneration of new
woodland.
On the other hand, minimal disturbance
can replicate natural events and be
beneficial to the habitat and wildlife
community. For example, to fell a few
trees in a woodland replicates natural
wind blow, creating pockets of light where
flowers can thrive, making way to shrubs
for nesting birds and eventually a tree will
fill the gap creating uneven aged trees
and therefore more structural diversity and
so more niches for wildlife to occupy.
Unfortunately, long gone are the days
when animals like wild boar roamed
the woodlands of Norfolk fulfilling their
ecological roles, rooting up the ground,
reducing bracken and bramble and
allowing flowers to germinate and flourish.
However, we can learn from nature and
try and replicate these techniques for the
benefit of wildlife.
The Species Diversity Hypothesis
makes for fascinating further reading.
In a nutshell the research states that
maximised species diversity occurs when
the levels of disturbance is neither too
regular nor rare. Species thrive when
small levels of disturbance occur as
different habitat successional stages are
created, therefore more niches for wildlife
to occupy.
Please feel free to contact the Countryside
Rangers with any questions or requests
for further information regarding the Great
Butterfly Project.
By Will Fitch
Anne-Marie.Katnoria@North-Norfolk.gov.
uk
Will.Fitch@North-Norfolk.gov.uk
Example of one side of a woodland path we
hope to create - structured and wildlife friendly
with grass and wildflowers going into bramble,
shrubs, young trees and finally mature trees.