Field Meetings, 2017


19 March - Croxley Common Moor

Croxley Common Moor is a Local Nature Reserve and Site of Special Scientific Interest covering forty hectares beside the River Gade, which flows next to the Grand Union Canal. This small area hosts over 250 plant species thanks to a mixture of wet and dry soils and the fact that it has never been farmed. 

Graham Everett, Secretary of the Friends of Croxley Common Moor, guided six members and one visitor around the reserve on an overcast afternoon with a cold wind. It was too early for many flowers to be out but at least Graham was able to show us where to look later in the year! We did see lesser celandine, white deadnettle, dandelion and bittercress, as well as enclosures to protect petty whin and dyer’s greenweed. These are the food plants of the Slate Sober Moth, of which the Moor is the only UK site in recent years. Broom and gorse are prevalent on the acid soil of the reserve, whereas heather occurs in the wet areas. There is one small chalk depression on the east side of the site, which has a distinctive flora in summer. The river is lined with hemlock water-dropwort. Trees include hawthorn, blackthorn, a few cherries by the river, large ashes which were in bud, a purging buckthorn and a field maple. Considering the time of year, we were surprised to find various fungal fruiting bodies in the grass. 

A few buff-tailed bumblebees were active despite the chill. The reserve has a striking abundance of anthills, some of which may be decades old. These attracted green woodpeckers during our visit. Other birds seen were black-headed gull, blue tit, carrion crow, greenfinch, kestrel, little egret, magpie, mallard, mistle thrush, moorhen, pied wagtail and wren; we also heard a chiffchaff. The reserve has a rabbit warren and we came across some molehills. There was some frogspawn in the river. 

This was an interesting visit to a site with a lot of diversity for its size. Thanks to Graham for showing us around and to Alan Power for arranging the trip. 


22 April - Chorleywood Common and Carpenters Wood

Five members and one visitor (soon to become a member) started the visit on the south side of Chorleywood Common, where we soon saw a kestrel, a green woodpecker and a peacock butterfly. We set off anticlockwise past flowering fruit trees and gorse bushes, seeing a jay and a treecreeper in the wooded part of the common. We also came very close to a mistle thrush and were able to see the clearly separate, round spots that distinguish it from the streakier song thrush. We examined some of the ponds but they were in a poor state, which is due to infestation by bogbean according to local botanist Dr Brenda Harold. Near our starting point, we noticed an oak tree with many oak apple galls, some very large, and saw a green woodpecker fly up again – perhaps the same one as before! 

Other plant species in flower were: bluebell, cow parsley, dandelion, garlic mustard, green alkanet, herb Robert, holly, red campion, rowan and white deadnettle. Other birds seen: blackbird, blue tit, carrion crow, chaffinch, dunnock, great tit, magpie, red kite, robin and woodpigeon; blackcap, chiffchaff and goldcrest were heard. Insects included St Mark’s fly and unidentified butterflies, bees and a small wasp. 

One member then left and the other four of us moved on to Carpenters Wood, an area of ancient woodland on the northwest side of Chorleywood. The main attraction of this site was a large area of coralroot, an attractive pink flower with a patchy national distribution. The woodland floor also featured swathes of bluebells and dog’s mercury, an indicator of ancient woodland. We were pleased to see and hear song thrushes and the other notable animal sighting was a hornet which I almost trod on! 

Other plants flowering in the wood were: dandelion, dog violet, cowslip, garlic mustard, ground-ivy, herb Robert, holly, wood avens and wood spurge. Birds encountered were: blackbird, chaffinch (heard), goldcrest (heard), great tit, stock dove (heard), woodpigeon and wren (heard). Insects were brimstone and orange-tip butterflies, a queen wasp, a bee-fly and a possible common carder bee. Grey squirrels were also seen; two weeks ago I observed two rabbits near the edge of the wood. 


14 May - Withey Beds Local Nature Reserve

Seven members travelled to Rickmansworth to join a public tour of this Local Nature Reserve, guided by members of the Friends of the Withey Beds and rangers from Three Rivers District Council. We started the walk by following the Grand Union Canal and then joined the Ebury Way. Along this section the birds seen were Canada goose, coot, jackdaw, woodpigeon and wren, while chaffinch and ring-necked parakeet were heard. The plants in bloom along the path were cleavers, common vetch, cow parsley, field forget-me-not, garlic mustard, germander speedwell, greater celandine, green alkanet, hawthorn, herb Robert, traveller’s joy, white deadnettle and wood avens.

We came to a group of fishing lakes, originally gravel pits dug during the construction of the canal, and were shown around by a member of Watford Piscators angling club. The lakes are stocked with carp, bream, roach, rudd, perch, chub and bleak, and are fenced against otters. Here we saw black-headed gulls, great crested grebes, green woodpecker, mallards, mute swan, tufted ducks and a whitethroat, as well as hearing chiffchaff, great tit and robin. There were white waterlilies in the lakes and the flowers added to the list around the lakes were comfrey, creeping buttercup, daisy, dandelion, dovesfoot cranesbill, ground-ivy, red campion and white deadnettle. We also saw bumblebees and butterflies, namely brimstone, orange tip and a blue species, probably holly blue. 

Across the road from the fishing lakes is the Withey Beds reserve itself, one of the last few wetlands in Hertfordshire, although it was very dry on this occasion after a spring drought. Our guides pointed out stingless nettles and the World War II pillbox which is used as a roost by bats. We also saw pond skaters on the river, peacock butterflies, a cardinal beetle, chicken-of-the-woods fungus, and a grey heron flying over. Along the path we paused a number of times to lift reptile mats and were pleased to see several slow-worms and young grass snakes, one of which was caught by a ranger so we could all have a good look at it. This was an exciting conclusion to an interesting visit.  

Thanks to Alan Power for leading our group, and to all the guides.


16 July - Bernwood Forest and Meadows 

Five members joined a group from Butterfly Conservation to explore the Forestry Commission-managed area of the former royal hunting forest of Bernwood. We were particularly keen to see purple emperors, which had emerged early this year, and eventually found a female flying around sallow trees, perhaps in search of an egg-laying site. After the BC members left, we toured Berks, Bucks and Oxon Wildlife Trust’s Bernwood Meadows, where the many wildflowers grew in clear rows, showing the ridges and furrows of the ground.

As well as the purple emperor, the butterflies we saw were brimstone, comma, common blue, Essex skipper, gatekeeper, green-veined white, large skipper, large white, marbled white, meadow brown, peacock, purple hairstreak, red admiral, silver-washed fritillary, small copper, small skipper, speckled wood and white admiral – a total of 19 species, possibly a record for the society! Nor were they the only representatives of the Lepidoptera, as we also saw six-spot burnet moths, and many cinnabar caterpillars feeding on ragwort.

Other notable insects were wood ants swarming over their impressive hills; emperor and brown hawker dragonflies; pondskaters and water boatmen in a small pool; soldier beetles, a longhorn beetle, a scorpionfly and red-tailed bumblebee. As we expected at this time of year, birds were more elusive and the only species noted were red kite and lesser black-backed gull.

There was a wide diversity of plants in flower in both the woodland and grassland habitats: agrimony, betony, bramble, common bird’s foot trefoil, common centaury, common knapweed, creeping cinquefoil, creeping thistle, eyebright, great willowherb, hedge bindweed, hogweed, lady’s bedstraw, meadow buttercup, meadowsweet, ox-eye daisy, perforate St John’s wort, pineappleweed, ragwort, red bartsia, red clover, scarlet pimpernel, selfheal, spear thistle, tall melilot, teasel, tormentil, tufted vetch, upright hedge-parsley, white clover, wild carrot, wild parsnip, woody nightshade, yarrow and yellow rattle.

As this species list shows, it was a very successful walk – thanks to our leader Andrea Polden and the Butterfly Conservation members.


16 September - Great Kimble Box Woods

Four members and one visitor set out from the car park by Ellesborough Church to begin the walk by crossing Beacon Hill below the summit, giving us an expansive view over the Vale of Aylesbury. The sheep pasture contained some chalk grassland flowers such as field scabious, eyebright, clustered bellflower, common rock-rose, wild thyme and harebell. We observed a buzzard perched in a dead tree before entering the largest native box woodland in the country. The dense-textured wood was used historically to make engraving blocks, lace-making bobbins and musical instruments. The box trees have long straggling stems that are hard to describe as trunks, giving the woodland a tangled, impenetrable look in the gloom created by the dark evergreen foliage.  

It took us only a short time to cross the box wood, and the rest of our visit covered more chalk grassland and another woodland dominated by ash and sycamore. Having watched a crow mobbing a red kite and a buzzard overhead, we noticed more grassland plants still in flower such as red bartsia, common toadflax, mignonette, yellow-wort and lady’s bedstraw, which stopped flowering in Chesham several weeks ago. We heard a stock dove and saw meadow pipits, swallows, house martins, a chiffchaff and a green woodpecker. There was a variety of fungi, most of which we could not identify except for candlesnuff fungus and King Alfred’s cakes; one large funnel-shaped mushroom in the woods was ‘decorated’ with a fox dropping.  

On the other side of Ellesborough Church, we looked at a pond and saw a moorhen; purple loosestrife and rosebay willowherb (not great willowherb, as we might have expected in this habitat) grew on the banks. By this time the sun had come out and we watched red admiral and comma butterflies, as well as various bees, feeding on ivy flowers. There was also a dragonfly flying too quickly to be identified, and some of us sampled the fruits of a damson tree. As we headed back to the car, I had a good view of a small copper butterfly while the others were busy watching a kestrel. 

Other species recorded were: 

Birds – blue tit (heard), carrion crow, great spotted woodpecker (heard), jackdaw, magpie and woodpigeon. 

Plants in flower: agrimony, black horehound, bramble, carline thistle, common knapweed, common vetch, creeping thistle, daisy, dandelion, goat’s-beard, herb Robert, hogweed, meadow buttercup, mouse-ear, nipplewort, perforate St John’s wort, pineappleweed, ragwort, red clover, selfheal, shepherd’s purse, stemless thistle, upright hedge-parsley, welted thistle, white clover, white deadnettle, wild parsnip, wood avens, woody nightshade and yarrow.

Insects: craneflies, large and small white butterflies. 

This is an excellent number of species – thanks to Trevor Brawn for leading the walk.