Tag Archives: Chalk Grassland

Hutchinson’s Bank, Grey July Day, Brilliant!

Toadflax Brocade moth caterpillar on Purple Toadflax
White-Tailed Bumblebee on Greater Knapweed
A Spotted Hoverfly on Weld
Crab Spider on Pyramidal Orchid
Soldier Beetles on Wild Carrot
Soldier Beetles Mating
Marbled White
Six-Spot Burnet Moth
Kidney Vetch
Female Small Skipper
Marjoram, a characteristic flower of Chalk Grassland
Parasitic Wasp
Chrysomelid Flower Beetle on ? Rough Hawkbit
Plume Moth
Pyramidal Orchids in Chalk Grassland
In the evening, I gave my ‘Urban Nature Reserve’ talk to a local group

Insects (and Flowers) of Chalk Grassland at Aston Rowant

6-Spot Burnet Moth side view with proboscis nectaring on Marjoram, antennae iridescent blue. Extremely flighty on a really hot day!
6-Spot Burnet Moth on Marjoram, Red on Iridescent Green (like the related Forester Moth, which flies here earlier in the year)
6-Spot Burnet Moth on Marjoram, same insect, looking Red on Black. The brilliant conspicuous coloration is evidently aposematic, more or less honestly warning that the insects are toxic, containing cyanogenic glucosides. A recent article finds, however, that the most toxic burnet moths are not more aposematic, i.e. there is no quantitative relationship. (But wouldn’t the less toxic moths evolve to look like the most toxic ones, as it’s safer…)
Moulting Grasshopper
Hoverfly on St John’s Wort
A magnificently large Parasitic Wasp on Hogweed
Soldier Beetle on Hogweed
Pyrausta nigrata: a beautiful chocolate-brown Micro Moth of downland with a wavy wing bar, among the wild Thyme (that’s how small it is)
Common Blue butterfly on Self-Heal
Marbled White on Scabious
Dark Green Fritillary (with quaking-grass above). Not only rare, but very flighty! I was happy to get this long shot through the grass.

There were also Small Whites, Meadow Browns, Gatekeepers, Small Skippers, and possibly Chalkhill Blues about.

A magnificently short, gnarly Beech getting a good toe-hold on the Chalk
Well this probably is a Chiltern Gentian, the flowers are large, and showier than the Autumn Gentian; pinker than the camera has made it look, too

Therfield Heath, Royston – surviving chalk grassland in East Anglia

On Therfield Heath SSSI (Royston Hill) with Yellow Rattle, with the plains of Cambridgeshire behind

Much of East Anglia is flat, and very low-lying, indeed parts of the Fens are basically at sea level. But there are some hills, and even a Chalk escarpment. It’s pretty low, but still affords a fine view northwards across the plains. The nearly complete “failure of a major escarpment” is the result of the Ice Ages – the ice sheet, maybe a mile thick, ground interminably over the hills and plains, reducing most of the chalk to rock flour with flints, creating the sticky Boulder Clay that carpets much of eastern England. But at Royston, a delightful range of low hills survives, and has somehow survived the plough and the developers.

Yellow Rattle

The grass of Therfield Heath (Royston Hill) is thinned by the parasitic Yellow Rattle (Orobanchaceae, the Broomrape family of parasitic plants): it helpfully weakens the grass, allowing in many other flowers, so it’s a bit of a Keystone Species, one on which the health of the ecosystem depends.

A colourful assemblage: Yellow Rattle – Red Clover – Birdsfoot Trefoil

The plants let in by the weakening of the grass include a colourful and increasingly rare assemblage, which includes Kidney Vetch, Birdsfoot Trefoil, Rockrose, Thyme, Wild Mignonette and many others.

Rockrose and Thyme, attractive plants of Chalk Grassland

The flowers in turn support butterflies including Marbled White, Meadow Brown, and Small Heath. Half-a-dozen Skylarks were singing all around; one got up pretty close to us for a brief song-flight, quickly followed by several of his neighbours. A Swift dashed overhead. All these once-familiar and widespread species are becoming rather special, a measure of the ecological disaster that has spread not just across England but across Europe and, really, the whole world.

Kidney Vetch

Meadow Brown on Thyme

Small Heath

Wild Mignonette

Therfield Heath landscape with Elder-Hawthorn bush

Greater Knapweed

Perforate St John’s Wort with interesting small pollinators

It’s interesting to see a pattern in the distribution of plants. I last saw Dropwort on Helsington Barrows, a limestone hill at the southern edge of the Lake District (not a place with much limestone, given the area’s ancient volcanic rocks and slates). Here it’s on a very different form of limestone, chalk, but if the soil is alkaline and supports open grassland, that’s fine with Dropwort.  It’s a plant with a beautiful foamy white cluster of flowers on a rather isolated stalk rising from the grassland. The attractive foaminess is reminiscent of Meadowsweet, Filipendula ulmaria, and indeed Dropwort is in the same genus: it’s Filipendula vulgaris, though it could hardly be called common these days.

Dropwort, Filipendula vulgaris

Orchids Surviving, Butterflies Vanishing in West Wiltshire

I had the good fortune to get down to West Wiltshire in hot if sometimes humid summer weather.

Pyramidal Orchid in Flowery Meadow
Pyramidal Orchid in Flowery Meadow

It was a pleasure to find the Pyramidal Orchid in a flowery meadow near a town: despite the dog-walkers, the increasingly uncommon flowers were clearly spreading from a small patch across the meadow, which is mown annually.

Less pleasantly, there were next to no insects pollinating the flowers: we saw one Small Tortoiseshell, a fly or two, and one (white/buff-tailed) bumblebee. It was a stark contrast to the masses of bees and beetles I’ve seen on the reserve in London. Of course, in London there is now very little use of pesticides, and basically none on an industrial scale.

This year (2014) does seem to be particularly poor for butterflies. It was an extremely warm winter and a very wet and windy spring, so I wonder if the result has not been a bad spring for insect pests … and perhaps, whether England’s farmers have not sprayed insecticide especially heavily? It’s a question that could clearly be answered by someone. If the answer is yes, then our ‘useful insects’ have suffered very heavily as a consequence.

The next day we went to Cley Hill, a western outlier of the Salisbury Plain chalk downs, sticking up above the plain below the chalk escarpment.

Bee Orchid
Bee Orchid

In the short grass, full of lovely flowers – Sainfoin, Milkwort, Horseshoe Vetch – were Bee Orchids, and happily both bumblebees in this special place protected by the National Trust and Burnet Moths – mostly Five-Spot Burnet, with some Transparent Burnet too, quite a treat.

Five-Spot Burnet Moth
Five-Spot Burnet Moth

Transparent Burnet Moth
Transparent Burnet Moth

On the top of the hill, above the Iron Age earthworks, we came across a group of about five Wall Brown butterflies, all very tatty and worn: perhaps they had been blown across the Channel from France on the warm southerly wind that is accompanying this anticyclone (centred to the east). Nearby were a few Brown Argus, small butterflies in the Blue family: not uncommon in France, far from common in England. Their coloration may seem odd for the Blue family, but females of quite a few species are brown, contrasting with their bright blue males, so the genes for ‘brown’ are clearly available: perhaps it takes just one or a few genetic switches to turn on brownness in both sexes rather than in just one.

In several places on the hill, often on bare chalk paths or short grass, we saw the glowing blue and purplish blue of Adonis Blue butterflies, with their chequered wing borders. So we saw some rather special butterflies, though with the definite feeling that they are only just hanging on in the area.

Milkwort, once a common plant in (cow) meadows
Milkwort, once a common plant in (cow) meadows

The hill is also host to Chalk Fragrant Orchid, Pyramidal Orchid, Spotted Orchid and more: it was lovely to see them all, though we were moved on swiftly by an anxious pair of Skylarks circling rather low overhead, trying to get back down to their nest, clearly not far from where we were sitting. All around in the thorn bushes were Tree Pipits, singing away, with some twittering Goldfinches and one Yellowhammer, my first of the year: yet another species that was once commonplace in every hedge.

 

Of Witch’s Brooms and Anthills

Down to Aston Rowant on a fine clear sunny day with a cold East wind that brought spring migrants like the Ring Ousel, a rare blackbird of mountain and moorland. I saw a probable one diving into a juniper bush; they like to stop off on the scarp of the Chiltern Hills as the next best thing to their favoured moors, before flying on to Wales or wherever.

Anthills dotting Aston Rowant chalk grassland
Anthills dotting Aston Rowant chalk grassland

The scarp slope of the relatively hard Chalk falls steeply to the broad plain of the soft Oxford Clay below, to the West. Much of the grassland has been destroyed for agriculture, either falling under the plough or simply being ‘improved’ as pasture with fertiliser, encouraging long grasses at the expense of the wealth of flowers that once covered the English countryside. Happily, here in the reserve and in quite a few places on the Chilterns, the steepness of the land has discouraged improvement. The chalk grassland is dotted with hundreds of anthills, the tiny yellow ants living all their lives below ground, tempting green woodpeckers to come out and hunt for them.

Whitebeam coming into leaf
Whitebeam coming into leaf

The trees and flowers are visibly weeks behind those of London. The Whitebeam is just coming into its fair white leaves, which look almost like Magnolia flowers in their little clusters newly burst from the bud. But the tree’s name comes from its white wood, not its leaves.

Witch's Brooms
Witch’s Brooms

At the bottom of the scarp, a field away from the Ridgeway which follows the line of hills for many miles, Hornbeams and Birches marked a change in the soil, which must be neutral or acid down here, compared to the strictly alkaline rendzinas and brown earths of the chalk. One of the Hornbeams looked as if it was oddly full of Mistletoe, but up close it proved to be a mass of Witch’s Brooms, growths of the tree itself caused by an infection.