To most people, wild flowers and birds are probably the most obvious wildlife at Rawcliffe Meadows but a great multitude of other species make the Meadows their home. Hundreds of different types of invertebrates inhabit the grassland, hedgerows and ponds. Surveys of these ‘mini beasts’ can provide us with valuable insights into the biodiversity of the site and guide the way we manage it.
A small survey of beetles was undertaken in summer 2013 by Martin Hammond and Bob Marsh, focussing on under-recorded parts of the site. Some 178 beetle species were recorded and the total number found at Rawcliffe Meadows is now a remarkable 540, representing around 13% of all British beetles.
Record counts of the endangered Tansy Beetle from the pond banks (521 adults on 1st September) and New Meadow verges (52 on 13th September) show how these populations are benefiting from careful management of their habitats. No Tansy Beetles were found at New Meadow in 2010/2011, so fencing to control grazing plus additional tansy planting has clearly been beneficial. FoRM are working to establish new tansy patches to enable these populations to expand.
The Necklace Ground Beetle (Carabus monilis) was an important new discovery as this is another threatened species identified as a priority for conservation in the UK Biodiversity Action Plan. It is an inch-long bronzy-coloured predator which is believed to be the most rapidly declining British ground-beetle. A small population was found in the Copse Meadow, where species-rich grassland was re-established in 2008. This shows that new areas of flower-filled hay meadow can be valuable for invertebrates as well as plants.
The diving beetle Agabus uliginosus is a speciality of seasonal pools which has its national stronghold in the Vale of York. It is categorised as ‘Near Threatened’ because its habitats are so vulnerable to land drainage. The continuing presence of a healthy population in the flood basin was confirmed. Other scarce species included two weevils, one of which (Oxystoma cerdo) feeds on tufted vetch, the other (Grypus equiseti) on horsetails.
The Cornfield yielded 82 species including several which require open sandy ground: FoRM hope to create a sand bank to provide additional habitat for these as well as other insects such as mining bees.
A number of beetles which develop in old or decaying wood were recorded, including good numbers of the uncommon Plum Longhorn Beetle (Tetrops praeustus). This confirms the value of old trees and ‘overgrown’ hedgerow shrubs around the site boundaries.
By Martin Hammond (c) 2013