Bradenham Butterfly Trail
This is a 2.3 miles (3.6 kilometres) circular walk from Small Dean Bank near Bradenham. The walk takes in a variety of woodland, grassland and scrubland habitats, which are managed by the National Trust to sustain biodiversity. Bradenham Woods, Park Wood and The Coppice have been designated as a Site of Special Scientific Interest. Twenty-eight species of butterfly have been recorded here, including small blue, Duke of Burgundy and dark green fritillaries. Marbled whites are abundant and there are many more common species.
Ideal conditions to see butterflies
What you will see will depends on the time of year and on the weather conditions. Warm, dry days from April to September are likely to be more rewarding. The walk also offers extensive views of the Chilterns Countryside near Bradenham.
National Trust car park in Smalldean Lane. Grid Ref. SU823989
From the National Trust car park in Smalldean Lane, turn left onto the lane, following it downhill towards Small Dean Farm. This is usually a very quiet lane, but please keep a look out for traffic. After 250 metres, you will reach the buildings of Small Dean Farm. Here turn left following a footpath sign. Take a track between some out buildings and continue until you reach an open field. Here turn left and follow the path in a straight line along the field boundary for 130m, towards a wooden gate in a gap in the hedge ahead of you.
Go through the gate and follow the path steeply uphill through an area of grass and scrub vegetation. To your right is a field with numerous round anthills built by yellow meadow ants.
Grass and Scrubland Butterflies
Chalk grasslands can be home to a diversity of moths and butterflies, many of which are threatened nationally. Scattered scrub provides shelter and food plants and supports a range of other insects. The soil here is thin, dry and nutrient-poor, but it supports a wide variety of alkaline tolerant plants including many caterpillar food plants such as common birds-foot-trefoil, horseshoe vetch, kidney vetch, cowslip, common rock-rose and various grasses. On this warm southwest-facing slope, patches of scrub provide shelter and structural variation. Characteristic butterflies (depending on the season) include small skipper, Lulworth skipper, silver-spotted skipper, dingy skipper, grizzled skipper, green hairstreak, small blue, brown argus, northern brown argus, common blue, chalkhill blue, Adonis blue, Duke of Burgundy, dark green fritillary, marsh fritillary, wall, marbled white, meadow brown and small heath.
At the top of the field, go through another wooden gate and up a short steep slope into Park Wood to meet a crossing track. Turn right along the track, which initially curves left, then eventually curves to the right as it heads steadily uphill before levelling out and then then descending again. Ignore all side paths and follow the track for about 400m through the beechwoods until you reach a fork. Take the right fork, which is effectively straight ahead. After a short distance you will reach another gate leading out of Park Wood into a field.
Woodland butterflies such as the speckled wood, thrive in sunny glades within the wood. They can often be seen competing for patches of sunlight. The caterpillars feed on grasses, but adults feed on flower nectar and honeydew produced by aphids. Other characteristic butterflies (depending on the season) include brimstone, purple hairstreak, white-letter hairstreak, black hairstreak, white admiral, purple emperor and silver-washed fritillary.
Turn left, following the edge of the field, with Park Wood on your left. The path heads steadily downhill until it reaches a wooden kissing gate next to a field gate. From here you will have a clear view of Bradenham Village in the valley below. Go through the gate, taking the second track on your left that leads up a short slope to a metal field gate and a metal kissing gate.
Chalk grassland is a rich, ancient and colourful habitat, but it is not entirely natural. As long ago as the Bronze Age, the land in the Chilterns was cleared of trees for grazing animals, so for over two thousand years, the cattle, sheep and rabbits introduced by people have helped to stop scrub species, such as hawthorn, bramble, dogwood and birch, from re-growing, and from shading out the sun-loving flowering plants that the butterflies enjoy. In some places the grazing animals still do their work, nibbling off the young shoots of scrub plants, but the reduction in rabbit numbers, and the impracticality of grazing sheep and cattle on some of our sites, means the National Trust rangers and volunteers sometimes have to lend a timely hand.
Go through the gate and follow the edge of the field uphill, again with Park Wood on your left. On your right there are distant views of Bradenham, Bradenham Valley, and as far as West Wycombe Church. After you have passed the path’s summit it starts to descend to another metal kissing gate.
Go through the gate and head downhill across an area of grass and scrub vegetation. Take care as the first few metres after the gate are very steep and the path can be slippery after wet weather. On reaching the bottom of the slope, turn left onto a wide track and head towards a set of wooden gates.
Until relatively recently, this area was a coniferous forestry plantation, although it was originally rough pasture. In recent years, the National Trust has cleared the trees. No seeding or planting has taken place, however a wide range of chalk grassland native wildflowers have grown from dormant seed, creating a habitat suitable for many species of grassland butterfly. Look out for any of the following species (depending on the season): small skipper, Lulworth skipper, silver-spotted skipper, dingy skipper, grizzled skipper, green hairstreak, small blue, brown argus, northern brown argus, common blue, chalkhill blue, Adonis blue, dark green fritillary, marsh fritillary, wall, marbled white, meadow brown or small heath.
Head through the gate and continue following the wide track gently uphill, ignoring branching paths. After 300 metres, the path curves to the left. You soon see a short, steep wooded bank to the right of the track with a chain link fence running along the top and with old pillboxes behind. This is the boundary fence of RAF High Wycombe at Walters Ash. The track bends left uphill away from it then levels out. Continue following the main track as it winds through an area of beech woodland, then an area of relatively young birch trees and then back to mature beech. At this point, you meet again the boundary bank and fence. When this comes to an end and on a left hand bend in the track look out for a clear but narrow woodland footpath on your left, which descends through the beech woodland.
Park Wood and Bradenham Beeches
Some butterflies, such as the silver-washed fritillary, enjoy the summer shade of woodlands, and they often feed on the nectar of flowering plants, such as ivy and wood sorrel, that grow on the woodland floor. You may find butterflies early in the morning, basking in small dappled pools of sunlight, or in clearings left by fallen trees. In places, woodlands can become, dense and almost impenetrable to light, preventing the smaller plants from growing. To help the butterflies, it is important to provide enough light for the flowering plants, on which and they feed, and this involves thinning out dense woodland, removing parts of the under-canopy and removing carefully selected trees and branches. This way, enough sunlight can penetrate through the tree canopy, allowing the woodland flowers to grow and to thrive.
Turn left onto the woodland path, following it as it winds its way downhill for about 100 metres. You will soon see a wood gate ahead of you. Go through the gate into the nature reserve at Small Dean Bank. Follow the steep downhill path across Small Dean Bank, back to the car park where you started.
Small Dean Bank
This is one of two local sites where the National Trust has successfully re-introduced the rare Duke of Burgundy butterfly. In 2000 the Trust harvested eggs from a Duke of Burgundy colony in the Ivinghoe Hills and from these adult butterflies were released at Small Dean Bank and Park Wood in the Bradenham valley in 2011. Work was also done to ensure the habitat at these sites is suitable for the butterfly's lifecycle. The reintroduction has proved to be very successful as His Grace the Duke of Burgundy, to use its full grand name, is increasing in number. This is a great conservation success story for a species which on a national scale is one of the most rapidly-declining butterflies in the UK. In March 2017, the pupae of the rare Purple Emperor butterfly were discovered near here.
National Trust car park in Smalldean Lane. Grid Ref. SU823989
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