Barton Fields Update, 2004
Two of our group, Adam Hager and Jo Cartmell undertook an Orthoptera survey last Summer and recorded five species: Long winged Conehead, Roesel’s Bush Cricket, Oak Bush Cricket, Meadow Grasshopper and Field Grasshopper. Roesel’s Bush Cricket and Long winged Conehead were once unknown in Oxfordshire but have spread to the county in recent decades, probably due to climate change.
I have been doing bird surveys of the site since May 2001 as part of Oxford Ornithological Society’s ‘Patchwork Scheme’. I am pleased to have recorded a total of ten warbler species, including Grasshopper Warbler and Cetti’s Warbler. However a notable change in the last two years has been a decline of Sedge Warbler numbers, and a corresponding increase in Common Whitethroat. Sedge Warbler prefer wetland so the decline could be due to drying out of the field area due to lowering of ground-water level. Gravel is being extracted from an adjacent pit and we suspect that pumping out of this pit is drying out surrounding land. We hope this will be reversed when the pit is restored as a lake in a few years time.
The catastrophic decline of Water Vole in the UK is well documented, however the two streams flowing through Barton Fields are now a stronghold for ‘Ratty’. Jo Cartmell and her helpers have become experienced WV recorders and have found numerous WV signs and quite a few recent sightings in the Eastern Drain, which runs the length of Barton Fields. Radley Park Stream, also flows through Barton Fields but also run through the Abbey Fishponds Reserve and continues beside Audlett Drive, past the new Leisure Centre before entering our site. Radley Park Stream has become a WV haven over most of its length. We believe this is due in part to the clearing of Himalayan Balsam from its margins, which has allowed native plants, on which ‘Ratty’ depends, to flourish.
Himalayan Balsam is an alien and invasive annual plant, preferring shady stream margins and woods and grows up to 2m high. It is a very prolific plant and when the seedpod is touched it bursts explosively, scattering the seed widely. When established, it completely shades out native plants so that there is only bare soil beneath. However it is shallow rooted and can be pulled up easily. This is fortunate since we have been faced with removing 20,000 to 30,000 plants each year! We have put in a lot of effort into clearing this alien from Barton Fields and adjoining streams, in the last two years. It must be said that Marjorie White’s zeal for this task has inspired us all. She and her helpers have been responsible for eliminating this plant from the Abbey Fishponds Reserve and much of East Abingdon! We are hoping that after two years pulling, next year the HB seed bank in Barton Fields will be depleted, making our job a lot easier.
The grassland of Barton Fields has a good number of herb species such as Fleabane, Sorrel, Ox-eye Daisy, Self-heal, Wild Carrot, Goat’s-beard, Tufted Vetch and Meadow Vetchling. Our aim is to increase plant diversity and to achieve this, a trial area is mown each Summer, with the aim of reducing the incidence of rank species. Last year, we scalped turf from small plots in the mown area and sowed seeds donated by Camilla Lambrick. These seeds were of Common Spotted Orchid, Cowslip and Yellow Rattle. Cowslip and Yellow Rattle came up in good numbers this Spring and we are particularly pleased about the latter, since it is semi-parasitic on grasses, weakening their growth. This we hope will encourage other herb species to flourish.
Finally, we are much obliged to Steve Cartmell, the South Abingdon Scout Group and Adam Hager who constructed seven bat boxes for us. Some of these have been sited in trees on site. We are also very grateful to Cynthia Napper of ONCF, Mary Lambe and Ian Matten of the Vale WH DC for their substantial help and valuable advice.
David Guyoncourt
on behalf of the Barton Fields Green Team
PS We are always on the lookout for Green Team recruits – let us know if you are able to lend a hand.
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