summer plants of the upper meadows include Greater
Knapweed, Hardheads (=Lesser Knapweed),
Scabious, Meadow Cranesbill, Alexanders,
Meadow Vetchling, Yarrow,
St. John's Wort*, Great Mullein*
many others. Herb Robert is
found amongst the scrub.
(*notably on disturbed ground.)
Plants of Ancient Downland
indicators on the lower slopes include Dropwort,
Ladies Tresses (upper plateau), Hairy
of which are rarely found on pastures, restored wildlife meadows or agricultural
downland. Other downland plants that are more likely on the biodiverse
down herbland are Wild Thyme,
Thistle, Dwarf Thistle, Squinancywort,
Flax, Small Scabious,
Basil. There are other more widespread
wild plants like the Mouse-eared Hawkweed,
Rough Hawkbit, Lesser Hawkbit, Bird's Foot Trefoil, Ground
Speedwell, Field Speedwell, Sweet Violet,
and Yellow Wort.
Wild Flora and Fauna on Chalk flickr
Adur Wild Flowers 2009
A large part (724 acres) of the downs including Mill Hill were presented to the people of Shoreham in 1937.Local Nature Reserve. This is divided into about 11 acres of grassland and meadows above the ridge, about 9 acres of scrub, the copse and glades at the northern end, and about half of the prime Chalkhill Blue area of 6.4 acres of herbland remaining. 6 acres has been lost to a Sycamore woodland on the southern slopes.
This is low fertility chalkland not suitable for grazing. The top area is effectively a wild meadow and the lower slopes a rabbit warren dominated by prostrate (not the upright form) Horseshoe Vetch, Hippocrepis comosa.
Hill is nationally important because of its population of Chalkhill
Blue Butterflies. Estimates of the numbers
are notoriously inaccurate. In the 1950s
the population was estimated by R. M. Craske
be 50,000. This may be an exceptionally good year. I would estimate the
numbers at that time to be nearer 25,000 for Mill Hill only. After the
cattle grazing and thorn incursions the numbers plummeted to the most reliable
estimate in 1960
of 6,000. The new road and Sycamore woodland further denuded the Horseshoe
Vetch, Hippocrepis comosa,
and bare chalk downland to a figure I have estimated at a top figure of
3,000 Chalkhill Blue Butterflies at the turn of the millennium (counted
in 2003). Almost
all these butterflies are now to be found on the six acres of the lower
family lived at The Mill House, Mill Hill, from around 1933
until about 1967, and every July we saw the
"Butterfly Men" walking past onto the Downs. My father used to tell
us that they were interested in the blue butterflies."
Heather Clark (née Eager), Ryde, Isle of Wight
Postcode: BN43 5FH
Grid Ref: TQ 21170 07444 (upper car park)
Geographic Link OS Map
Google Earth Map
Magic Map of Mill Hill NR
Local Nature Reserve Designation
Natural England: Local Nature Reserves
Multi-Map (Bird's Eye View)
Grid Reference Finder
The butterfly lower slopes at Mill Hill are under serious threat by a natural process known as ecological succession where the woody shrubs like Privet, Brambles and Hawthorn invade the herb-rich slopes gradually turning the downs into woodland and eliminating the butterfly larval food plants especially the Horseshoe Vetch, Hippocrepis comosa, on which the Chalkhill Blue Butterflies rely. The remedy is by expert professional removal of the Privet on a regular basis. This job is now being undertaken by volunteers.
at Mill Hill
I disturbed a single Skylark from the plateau of Mill Hill on a hazy afternoon. It took flight after I thought I heard it singing earlier, but there were House Sparrows singing melodiously for a mate from the scrub, and it was too hazy to see a lark in the blue sky. Cowslips were flowering by some rabbit burrows (disused) on the middle open part of Mill Hill west of the top copse.
Spikenard (dead), Speckled Wood
Grizzled Skipper, MIlkwort with Pill Bug
the middle of the lower slopes I spotted just a single Grizzled
Skipper, followed by the small pyralid
Pyrausta nigrata, and later a Small
White Butterfly and a strong flying Peacock
Butterfly, and on my return journey a
Wood fluttered around the southern steps.
were now abundant but there still seemed
to be less scattered over the slopes than in previous years. MIlkworts
were poking out of the short vegetation.
I noted the top leaves were much longer than the leaves at the rosette
base. This is typical of the local Milkworts
which I have identified as Common Milkwort
vulgaris in previous years, but this
has not been confirmed. Occasional spiders
were spotted crawling rapidly over the undergrowth, mostly very small Fox
a small Wolf Spider, Pardosa, but
also a full sized Nursery Spider
and a tiny pale Crab Spider.
On a afternoon when the sun came out unexpectedly, I quickly spotted my first two Grizzled Skippers of the year on the lower slopes of Mill Hill, now decorated with Dog Violets, but much more sparsely than normal. A Common Bee-fly hovered above the violets and a Carder Bee flitted between the flowers quicker than my camera could focus. My first Brimstone Butterfly of the year fluttered past. The first of three Peacock Butterflies landed intermittently. No more skippers were seen.
Adur Butterfly List 2019
Caterpillars of the Adonis Blue Butterfly with attendant Red Ants
Most of the observed action occurred amongst the dense interlocking leaves on the lower slopes where a brigade of working mutualistic red ants, Myrmica sabuleti, were attracted by sugary secretions of the green and yellow caterpillars of the Adonis Blue Butterfly. The ants are meant to protect the caterpillars (some were fourth instar) and pupa from predation. Ben Greenway helped me find the caterpillars, but I found one for myself by following the ants activity.
larvae are green with yellow stripes running along the length of the body.
Unlike its close relative, the Chalkhill Blue,
the larva of the Adonis Blue
feeds by day. The larva has a Newcomer's gland in the 7th segment which
provides secretions that are attractive to ants. This is a symbiotic relationship
for, like many other blues, the Adonis Blue larva (and pupa) is afforded
protection by the ants from parasites and other predators.
Early instars feed by grazing on one side of the leaf, leaving the epidermis of the other side intact. When not feeding, the larva rests at the base of the foodplant, often on bare soil. Ants are known to bury the larva in a cell in the earth, where the ants continue to "milk" it for secretions. If not overwintering, this stage lasts around a month."
The primary larval foodplant is Horseshoe Vetch, Hippocrepis comosa.
Adonis Blue Life Cycle (UK Butterflies)
A small Fox Spider, Alopecosa, crawled amongst the undergrowth. The upright dead bronze and silver dead Carline Thistle plants were quite noticeable on the lower slopes, as expected.
Amongst the scrub on the upper part of Mill Hill, the white blossom of Blackthorn looked attractive against the blue sky. There were a few Cowslips south of the Reservoir (the only upper part of Mill Hill visited.)
I stopped in at Mill Hill and managed to find a Grizzled Skipper, the first of the year reported in Sussex.
19 March 2019
Wind-blown Hawthorn above the Ridge
a dull afternoon I made my first cursory visit of the year (after
a week of squalls) to Mill Hill, just to the
area around the Reservoir. A hunderd mixed
filled the cloudy sky. There were Sweet
Violets scattered sparsely over the undulating
area immediately south of the Reservoir. Clumps of Daffodils
were still showing. Even the small birds flying between the bare branches
were hard to discern as it was so dark. Some of the paths were muddy but
there was no standing water seen.
Mill Hill Wildlife Reports 2018 (Link)
Hill Wildlife Reports 2016 (Link)
Mill Hill Wildlife Reports 2015 (Link)
Mill Hill Wildlife Reports 2014 (Link)
Mill Hill Wildlife Reports 2013 (Link)
Mill Hill Wildlife Reports 2012 (Link)
Mill Hill Wildlife Reports 2011 (Link)
of Grasses (Link)
Mill Hill Grasses
Reserve is defined in Section 15 of
the National Parks and Access to the Countryside Act 1949,
as land managed for the purpose:
of providing, under suitable conditions and control, special opportunities
for the study of, and research into, matters relating to the flora and
fauna of Great Britain and the physical conditions in which they live,
and for the study of geological and physiographical features of special
interest in the area; or
SPECIES OF BUTTERFLIES DEPENDENT ON MILL HILL
(Estimated numbers for Mill Hill Nature Reserve only are in brackets)
Blue (3000 +)
Adonis Blue (50 -100)
Dingy Skipper (75)
Wall Brown (12)
Meadow Brown (300)
|Marbled White (50)
Speckled Wood (>50)
Green-veined White (2+)
Small Blue (5)
Large Skipper (10+)
Grizzled Skipper (20)
Brown Argus (>30)
Green Hairstreak ( a few)
The other species may breed on Mill Hill, but there main breeding area will be adjoining fields or slightly further away. e.g. Small Blue (included above), Small Copper, Small Tortoiseshell,Green-veined White, Peacock, Ringlet, Small White, Large White, Comma, Holly Blue, Orange Tip. (=10). There are huge variances each year for most species.
The following are immigrants &/or hibernators: Red Admiral, Painted Lady, Clouded Yellow.
The following have not been positively identified (because of ID difficulties): Essex Skipper. This species is now included for a local field on the Adur Levels within 500 metres of Mill Hill.
following was confirmed only in 2009:
following was confirmed only in 2014: Dark
The next one is no longer
found on Mill Hill but were there in the distant (1947) past: Grayling.
The next one has been recorded near Mill Hill in the middle distance past: White-letter Hairstreak
Skipper does not appear to ever have occurred
on Mill Hill
The Silver-studded Blue has never been recorded from Mill Hill
The Short-tailed Blue was recorded as a single immigrant in 1956.
A possible (unconfirmed) Brown Hairstreak Butterfly was spotted. A confirmed one was spotted nearby.
Brown Hairstreak and Silver-spotted Skipper have been confirmed from Mill Hill. The first is notoriously difficult to spot and was probably already there. The skipper may be a new addition, but it is small and not easy to spot, and there have now been numerous sightings
History of Mill Hill
Lower Adur Levels (MultiMap) including Lancing Clump and Mill Hill
Vetch, Hippocrepis comosa
First Draft of the Article for the Shoreham Society Newsletter