Hartslock Nature Reserve is located on the north side of the Thames between Whitchurch and Goring-on-Thames, Oxfordshire. The site is owned by The Wildlife Trust for Berks, Bucks & Oxon (BBOWT) and managed by its staff and volunteers.
The reserve is a beautiful south facing, unimproved chalk downland hill with stunning views over the river Thames and the Goring Gap region. The grassland is surrounded by ancient hedges and mixed Yew woodland and, although it is only small (11-acres or 4.4 hectares), it is home to a very wide variety of plants and animals, some of which are extremely rare. For this reason the government has designated it and the surrounding area a ‘Site of Special Scientific Interest’ (SSSI) and the whole Goring Gap region is an ‘Area of Outstanding Natural Beauty’ (AONB).
The wildlife on Hartslock is typical of unimproved chalk downland but unfortunately, due to modern farming methods and the increasing pressures on land in the south of England, this kind of habitat is becoming increasingly rare.
This year the orchid mapping has been beset by problems – not least of which has been the incredibly wet weather – but with the help of Gerry and the other volunteers we have kept roughly on schedule to complete it on time (or a little late). The only slight problem has been that I haven’t had time to update the databases yet and so haven’t been able to keep you all updated on the numbers.
Suffice it to say, that we have been finding plenty of plants and it looks as though this year should be as good as last year. But the flowering season is likely to be later than in the previous 2 years. There will be plenty of Monkey orchids flowering (we have seen the pikes forming) and the same goes for the hybrids. Two Lady orchids have sent up spikes and one of them has opened the first buds, but the plants are quite short this year.
If the weather warms a little then growth will progress faster but at the moment it looks like the second week in May is the earliest that visitors should come to the site to see the orchids. At the moment the lower gate is locked to prevent access and there are no guide tapes but we hope to open it up this coming weekend.
Today was my biannual walk round with Martyn Lane, my line manager at BBOWT. The general aim is to check what work needs to be done and to report back any issues to Martyn – requests for equipment etc. Today we managed to dodge the showers completely and it was gloriously sunny for the whole afternoon.
Insects were on the wing in good numbers, sunning and nectaring on dandilions and ground ivy. These included: Dingy Skipper (20+), Grizzled Skipper (1 very fresh), Small Heath (1), Peacock (1), Orange Tip (2), Osmia bicolor (a bee that nests in old snail shells), Gymnocheta viridis and lots of Bombylius major (bee fly).
Pasque Flowers were doing very well with about 10 clumps in flower.
 Pasque flower  Gymnocheta viridis
The recent warm & sunny Spring weather has really brought the insects out. On a walk last Wednesday I saw Brimstones & a Small Tortoishell butterfly plus a quite rare fly called Gonia picea. The site is also covered with tiny little Hairy Violets, all flowering beautifully. It just goes to show that it might be March and a bit chilly without the sun but wildlife is out there making the most of it 
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Gonia picea
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Gonia picea
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Hairy Violet
The wardens will be making the most of it too because this year’s Monkey Orchids are just starting to poke up through the grass and this can mean only 1 thing … the orchid mapping season has started!! We need to get all of the plants checked and mapped in and (hopefully) tagged before they start to flower and the visitors start arriving. The next few weeks should be really busy but it is always a fun time when we get the first chance to estimate how good a year it will be.
There is one thing for sure though, if we don’t get some rain soon we are very likely to see another drought, like we had last year, and which caused most of the flowering plants to abort. I love the sunny weather but I’m also praying for rain … and sometime soonish!
Sorry … bad pun intended! But the good news is that a hare was seen on the February workparty today – only fleetingly because it broke cover from some long grass at the base of slope 4 and was last seen bounding across the hill into slope 3! But I think that this is the first sighting of a hare on Hartslock … ever, so well worth reporting
The rest of the workparty was relatively uneventful but we managed to trudge through the snow to the far side of slope 4 and finished off the scrub management along that lower fence – a job that we have been slowly chipping away at all winter. The improvement to the cleared area is really obvious and I hope that the light will get in and help the grassland flowers to flourish. We intend to allow some of the scrub line to come back gradually over time, to provide more shelter for invertebrates but in the meantime they should be fine.
 Bastard Toadflax bug Spent a lovely afternoon pottering around Hartslock today with a friend … the showers held off for for most of the time and, with all the summer flowers in full bloom, the site looked really spectacular.
One of my favourite species-complexes centers on Bastard Toadflax (Thesium humifusum), a rare perennial of short-turfed chalk downland. The plant itself is quite small but its ‘politically correct’ common name of ‘Stars in the Grass’ aptly describes the dainty little white, star-shaped flowers and the way that the creeping branches climb through short grass and herbage. This plant is exciting enough for keen botanists to travel from miles around but rarer still is the little bug (Sehirus impressus) that lives by sucking the sap of only this rare plant. They are a dark gun-metal blue colour and similar to the commoner Pied Shieldbug. Today we saw an adult and many juvenile bugs – characterised by their red & black abdomens – see the photos.
Ever rarer still though is the mildew that only grows on Bastard Toadflax – Erisiphe thesii – this has only been recorded from Hartslock and forms a downy mildew on the tips of Bastard Toadflax stems. If you see Bastard Toadflax and it has a grey mildew then you are looking at Erisiphe thesii
No sooner have we seen the last of the Dingy skippers bite the dust then the next species are on the wing … what a crazy year it is. Today I spent a very nice time showing visitors around and while we admired the views we saw: quite a few Meadow Browns & Large Skippers; a female Chalk-hill Blue; a Small Tortoishell; and … a Dark Green Fritillary! In addition we saw quite a few tatty Common Blues and Small Heaths, a Brimstone and some other Whites (at distance).
The early emergence of mayflies has ended (Ephemera vulgata and danica) but now the real rarities are on the wing – Ephemera lineata.
Bee orchids are also just coming into flower, along with Bastard Toadflax, Yellow-wort, Clustered Bellflower and Thyme.
Found this really lovely giant aphid* today … it’s about 1cm long. There were also a few Ephemera vulgata & lineata plus all of the usual butterflies; a few demoiselles and perhaps 1 Club-tailed dragonfly.
(* Tony Irwin suggests that it might be Cinara piceae)
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NOTICE 1/5/2012: Dingy & Grizzled Skippers; Small Heath. Orange Tip, Green-veined White, Peacock & Green Hairstreak have all been seen on the wing recently. Two Lady orchids and 15 hybrids in flower - lots more (and all the Monkey orchids) in bud waiting for the weather to warm up!
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