Surveys

Survey of Bees and Wasps

Radley Lakes was visited on four warm days in 2018 and sampled for aculeate Hymenoptera. The resulting survey can be found here. All sampled bees and wasps were identified and the results compared with previous similar surveys of 2006 (author) and 2011 (Bioscan). In this survey 55 species of bee and 32 species of wasp were recorded, bringing the total number of species recorded since 2006 (in the immediate environs of the site) to 85 bees and 73 wasps. The identification of a new species of cuckoo bee to Britain, Stelis odontopyga warranted its own paper. Other notable results are: three species with fewer than 5 records in Oxfordshire Lasioglossum zonulum, Nomada flavopicta and Chrysis gracillima and the remarkable abundance of the mining bee Lasioglossum puncticole, which hitherto was thought to be rare in Oxfordshire. Recommendations for aculeate conservation are given, including a suggested reappraisal of the management of Common Ragwort Jacobeae vulgaris.

The Birds of Radley Lakes

cornorant at Radley Lakes

Cormorant pictured at Radley Lakes ©2019 Ben Carpenter

The ongoing survey of birdlife at Radley Lakes has been summarised by Ben Carpenter in a Powerpoint file (a more convenient PDF of which can be found here). The report has been compiled from 852 visits between 2009 and the present. The survey includes breeding bird surveys of habitats surrounding the lakes and notes the presence or absence of species from a count taken every fortnight

 

Meadow Brown butterfly on scabious

Meadow Brown Butterfly on Field Scabious © Jo Cartmell

More surveys to be done at Radley Lakes

Earth Trust has been working with the Centre of Ecology and Hydrology (CEH) to set up butterfly transects on Thrupp Lake and Areas G, H/I and J/P, the areas it manages at Radley Lakes. Transects are fixed routes through the area to be surveyed which are walked regularly and the number of butterflies of each type counted. This data is then fed into the national database, the Butterfly Monitoring Scheme (BMS). As Abingdon Naturalists also do transects, one in Barton Fields and the other in the Nyatt’s Field area, the County Wildlife Site area should be well covered for butterfly surveys.
 
Abingdon Naturalists are also about to start plant surveys on the same Earth Trust managed sites. Their findings will add to the data they have produced for their own site Barton Fields and also the Nyatt’s Field area over the years.

 

Butterflies Surveys at Radley Lakes 

Members of Abingdon Naturalists Society have been surveying butterflies in Barton Fields and Nyatt Field since 2011

Records are made weekly during the six months April to September, taking a circuitous route across the two sites. These transect records are reported to the UK Butterfly Monitoring Scheme and Butterfly Conservation.

Five recorders share the task of transect walking, providing a great opportunity to keep an eye on other wildlife as well as butterflies. Over the eight years we have accumulated a data set of over thirteen thousand records of 25 butterfly species. This data provides a good indicator of the health of the various habitats and their management.

One finding for Nyatt Field, is that there is a substantial reduction in abundance of ‘brown’ butterflies, which are grassland species after winter flooding. Notably, Meadow Brown numbers were reduced by 75% and Ringlet abundance reduced by 95%. In contrast, in Barton Fields, numbers of both species have remained fairly stable.


Ringlet Butterfly on Ox-eye Daisy © Jo Cartmell

We ascribe this to the effect on wintering larvae. Nyatt Field was under water for weeks at a time whereas in Barton Fields, only parts of the grassland were inundated for shorter periods. Both species over-winter as caterpillars within tufts of grass, and are likely to drown, when immersed for prolonged periods. Thanks to the five volunteers who do these surveys

David Guyoncourt
Abingdon Naturalists and FRL Executive

 

Volunteers clearing excess Ragwort from Area G © Lucy Tomkinson (not all the Ragwort is removed as it is the larval food plant of the cinnabar moth).

Whilst working in Areas G, H/I and Je/P this year myself and the volunteers have seen so much wildlife, some of the highlights for me have been Skylarks, Little Grebes, Sand Martins and hundreds of Marsh Helleborines!

Finally, I would just like to say a huge THANK YOU to everyone involved in the habitat work we’ve already carried out this year!

Lucy Tomkinson
Community Reserves Warden, Earth Trust