Photo 1 - Steep Dowland Slope North-East Of The Hill Fort 

Highlights

• National Nature Reserve on chalk downland owned and managed by English Nature
• Site crowned by iron age hill fort providing fine views
• One of the best sites in the country for Chalkhill Blue
• Flourishing colonies of Dark Green Fritillary and Silver-spotted Skipper
• Adonis Blue re-introduced by English Nature and gaining good foothold

Description

Old Winchester Hill is a National Nature Reserve on the South Downs just east of the village of Warnford in the Meon valley. It is also the site of an Iron Age hill fort with many prehistoric features still visible, such as earthworks, barrows and tumuli. The flat topped summit of the fort itself, complete with triangulation pillar provides fine views, especially south towards Portsmouth and the Isle of White.

This large nature reserve, owned and managed by English Nature, is noted especially for its flora, which includes at least 6 species of orchid, and of course for its butterflies. The butterflies thrive on the species rich grassland, whose low nutrient value acts as a natural barrier to vigorous encroachment by scrub. The diversity of species is further enhanced by the habitat variations resulting from the natural topography of the site and its prehistoric man made features.

Old Winchester Hill is one of the most prolific sites in the UK for Chalkhill Blue - their numbers across the whole reserve have been estimated to reach the low thousands in good years! It is also a very good site for Dark Green Fritillary, Silver-spotted Skipper, Marbled White and common species. Furthermore, in the early 2000s an experiment to re-introduce Adonis Blue by English Nature seems to be going reasonably well, with two widely separated colonies now gaining a foothold. 

Photo 2 - View South From the Fort Across Adonis Blue Re-introduction Site

For this feature, it is convenient to use these two widely separated locations for Adonis Blue as references, since other areas of the reserve can be readily accessed from one or other of them.  I will assume access is from the main car park (arrowed on this map), however for the fort area there is also limited road parking close to pedestrian entrances further south along the minor road. The next paragraph provides directions to the closest of the Adonis sites.

From the car park, enter the reserve through the gate and turn almost immediately right, passing in front of a gazebo shaped structure containing visitor information (take a look!). Continue through another gate and head straight down the grassy slope. Depending on time of year, species which can be found on this short cropped area of the slope include Chalkhill Blue, Meadow Brown, Small Heath and a few Silver-spotted Skippers. Towards the bottom of the slope, just before the path takes a left turn, pause and look around.  The area of more varied vegetation in front of you and to your left (arrowed on this map) is where the Adonis have colonised (including a small meadow at the bottom of the slope which can be accessed via a partially ‘flattened’ wire fence). Look for them in late May/early June and again mid/late August. Silver–spotted Skipper, Chalkhill Blue and Common Blue are also found in good numbers in this general area, according their flight periods. I have also recorded the occasional Grizzled Skipper, Dingy Skipper, Green Hairstreak and Clouded Yellow.

If you continue along the path as it turns left, you reach an area of steep open downland (Photo 1 at top of page). Look here for fast flying Dark Green Fritillaries during July. Although they can be quite numerous here (dozens or even scores) they rarely seem to settle for long and can be difficult to photograph on this site. In addition, departing from the paths is discouraged, bearing in mind the site was used in World War II for mortar testing. One can continue onwards through the section of woodland to another area of downland and then uphill (keeping to the paths!) to the fort area and the original Adonis Blue re-introduction site. However I will describe the route to the fort and this Adonis site as if making a separate visit, starting from the car park.

In this case, after entering the reserve from the car park, just continue along the main path. The fort is just over 1km from the car park, the path heading south parallel to road for about half that distance before turning right towards the fort. In the first section, Marbled White can be very numerous amongst the long grasses, as well as Small/Essex Skippers, Meadow Brown and Chalkhill Blue (which at peak season can be found in almost all grassland areas of the reserve). In July look over the fence on the right and watch for fast flying Dark Green Fritillary on the steep slope.

After the path takes a right turn, there are usually fewer butterflies to be seen along the section approaching the fort, except for some common Nymphalid species such as Red Admiral and also Chalkhill Blue, depending on time of visit. Now go through the gate marking the entrance to the fort area itself. Some areas of the fort (especially parts of the ramparts which surround the fort) may be roped off to protect nesting birds, but butterflies are normally plentiful even along the rampart edges (Chalkhill Blue, Silver-spotted Skipper, Small Heath, Small/Essex Skipper, Meadow Brown, Painted Lady and even the occasional Clouded Yellow) and a full circuit around the fort is worthwhile if time permits, perhaps with a foray to its flat summit where there is a triangulation pillar.

Photo 3 - Re-introduction Site for Adonis Blue

Adonis Blue re-introduction site is also excellent for Silver-spotted Skipper and Chalkhill Blue

The Adonis Blue re-introduction site (Photo 3) is on the sloping field/meadow running south from the fort and accessed via an open gate (shown in Photo 2). The Adonis can be found in late May/early June and again mid/late August towards the bottom of this field as the grass gives way to bushes and scrub. However their summer generation is outnumbered many times by Chalkhill Blue (which can be abundant here) and Silver-spotted Skipper. Common Blue are also found in the scrub areas near the bottom of the slope as well as the occasional Brown Argus.