Mill Hill (June 2013)
MILL HILL & the DOWNS
 
 
 WILDLIFE REPORTS 2019
 
 
Spring Downland Butterflies (May):
 
Adonis Blues (Photograph                    by Andy Horton)
Dingy Skipper                    (Photograph by Andy Horton)
Small Heath Butterfly
Grizzled Skipper
Adonis Blue Butterfly
Dingy Skipper
Small Heath Butterfly

Noticeable summer plants of the upper meadows include Greater Knapweed, Hardheads (=Lesser Knapweed), Field Scabious, Meadow Cranesbill, Alexanders, Pyramidal Orchids, Plantains, Melilots, Meadow Vetchling, Yarrow, Eyebrights, Musk Thistles, Hounds-tongue*, Perforate St. John's Wort*, Great Mullein* and many others. Herb Robert is found amongst the scrub.
(*notably on disturbed ground.)

Some Indicator Plants of Ancient Downland
 
 

Horseshoe Vetch (Photograph by Andy Horton)
Autumn Gentian
Horseshoe Vetch
Common Milkwort
Dog Violet
Autumn Gentian

Other indicators on the lower slopes include Dropwort, Autumn Ladies Tresses (upper plateau), Hairy Violet, all 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, Carline Thistle, Dwarf Thistle, Squinancywort, Fairy Flax, Small Scabious, Common Centaury and Wild Basil. There are other more widespread wild plants like the Mouse-eared Hawkweed, Rough Hawkbit, Lesser Hawkbit, Bird's Foot Trefoil, Ground Ivy, Germander Speedwell, Field Speedwell, Sweet Violet, Self-heal and Yellow Wort.
Wild Flora and Fauna on Chalk   flickr
Adur Wild Flowers 2009



 
OVERVIEW:

A large part (724 acres) of the downs including Mill Hill were presented to the people of Shoreham in 1937

Lower Slopes of Mill Hill, May 2006 

Just over 30 acres still remain as public open land and a 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

Link to                            the Mill Hill web page for 2009
MILL HILL HOMEPAGE
LOWER SLOPES 2008
MILL NATURE RESERVE & MAP
OVERVIEW CITATION
GRID REF FINDER

Horseshoe Vetch

Chalkhill Blues:

Mill 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 to 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 slopes.
Graham Hart in the 1990s estimated the numbers at 6,000. This is not out of the question and this would accord with the R. M. Craske estimate of 50,000. This would be the maximum population density that could be expected on the carpets of Horseshoe Vetch (based on German figures).
Protection of the current population requires man management of the scrub incursions, which means removal of the Privet

Text by Andy Horton Calcareous Grassland Message
"Our 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
Nearest 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

FEATURE:
 
2003
Threats to the Butterfly Downland site at Mill Hill
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. 

     2009

Mill Hill on

flickr
Mill Hill on

facebook


 
 
 
 
 
 
 

   Footpaths at Mill Hill
 
 
 
 

WILDLIFE REPORTS


17 April 2019
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.

Ploughman's Spikenard (dead), Speckled Wood
Grizzled Skipper, MIlkwort with Pill Bug

On the middle of the lower slopes I spotted just a single Grizzled Skipper, followed by the small pyralid moth Pyrausta nigrata, and later a Small White Butterfly and a strong flying Peacock Butterfly, and on my return journey a Speckled Wood fluttered around the southern steps. Dog Violets 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 Polygala vulgaris in previous years, but this has not been confirmed.  Occasional spiders were spotted crawling rapidly over the undergrowth, mostly very small Fox Spiders, Alopecosa, possibly a small Wolf Spider, Pardosa, but also a full sized Nursery Spider and a tiny pale Crab Spider.
Adur Milkworts

11 April 2019
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.

"The 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.

Blackthorn

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.)

30 March 2019
I stopped in at Mill Hill and managed to find a Grizzled Skipper, the first of the year reported in Sussex.

Report by Jonathan Crawford on Sussex Butterflies
Adur Skippers

19 March 2019

Wind-blown Hawthorn above the Ridge

On 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 gulls 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 of Hawthorn were hard to discern as it was so dark. Some of the paths were muddy but there was no standing water seen.
 

Bye-laws


 
 

Mill Hill Wildlife Reports 2018 (Link)

Mill 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)



Adur Valley & Downs on facebook

Identification of Grasses (Link)
Mill Hill Grasses
 



 
A Nature Reserve is defined in Section 15 of the National Parks and Access to the Countryside Act 1949, as land managed for the purpose:

(a) 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
(b) of preserving flora, fauna, or geological or physiographical features of special interest in the area; or for both these purposes.

17+ SPECIES OF BUTTERFLIES DEPENDENT ON MILL HILL FOR BREEDING:
(Estimated numbers for Mill Hill Nature Reserve only are in brackets)


Chalkhill Blue (3000 +)
Adonis Blue (50 -100)
Dingy Skipper  (75)
Small Heath (250)
Wall Brown  (12)
Meadow Brown  (300)
Marbled White  (50)
Gatekeeper    (200)
Speckled Wood  (>50)
Green-veined White (2+)
Common Blue  (>4000+)
Small Blue       (5)
Brimstone        (8)
Small Skipper   (>50)
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.

(=30)

The following was confirmed only in 2009: Green Hairstreak.
(=31)

The following was confirmed only in 2014: Dark Green Fritillary
(=32)

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

(=34)

The Silver-spotted 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.

17 August 2009
A possible (unconfirmed) Brown Hairstreak Butterfly was spotted. A confirmed one was spotted nearby.

2017
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

Adur Butterfly Page



 

History of Mill Hill

Aerial Map
Lower Adur Levels (MultiMap) including Lancing Clump and Mill Hill

Horseshoe Vetch, Hippocrepis comosa
First Draft of the Article for the Shoreham Society Newsletter
 
 

Link to the            Adur 2012 Nature Notes pagesLink to the Adur Nature Notes 2011            web pages

Link to            the Adur 2010 Nature Notes pagesLink to the Adur Nature Notes 2009            web pagesLink to the            Adur Nature Notes 2008 web pagesLink to the Adur Nature Notes 2007            web pages
Link to Adur            Valley Nature Notes 2003Link to the Adur Nature Notes            2004 Index pageLink to Adur Nature Notes 2005 Index pageLink to the Adur Nature Notes 2006            web pages