The new Sand Martin wall at Summer Leys
The satisfaction that comes from completing a project which yields instant results is, arguably, immeasurable and so it was in the case of the creation of a secure and permanent nesting site for Sand Martins at Summer Leys LNR.
Each year, Sand Martins have nested in the drainage holes in the old quarry conveyor loading ramp located on the permissive path along the disused railway, which is owned by Hanson UK and forms part of the Summer Leys perimeter walk. Numbers breeding here have ranged from one to five pairs.
Many Sand Martin nesting colonies are ephemeral affairs, with whole colonies frequently dispersing or shifting to new locations as suitable sand cliffs are created and destroyed over time. Therefore, in order to add a degree of habitat stability, local birders have for many years been keen to create a permanent, bespoke Sand Martin bank at Summer Leys so, at the end of March 2014, fifty new holes were drilled in the ramp wall to provide additional nesting opportunities for returning birds.
The ramp itself was built in the late 1970s/early 1980s to allow excavated gravel to be transferred from dumpers to a 3.5 km long conveyor belt that took the gravel to the Earls Barton processing plant. It was in use until the late 1990s and was originally planned to be removed at the end of its operational life, but later it was agreed that it should be retained as a potential location for a bird hide. A line of c.60 mm diameter drainage (weep) holes was built into the reinforced concrete headwall when the ramp was constructed and their use by sand martins was first noted in 2002 when “a few pairs” nested.
The wall was believed to be 200 mm thick but, after drilling, the first core was found to be 460 mm thick. The majority of the new holes are 64 mm in diameter (77 mm cores lined with 64 mm internal diameter pipe), but the central 11 holes on the top row are 62mm in diameter and are unlined. The cores extend through the concrete wall into the original “as-dug” gravel fill for around 800 mm. Gravel was scraped out behind the wall to create larger voids and these, and a short section of the core/pipe, were repacked with clean sand. The drilling work, which was funded by Hanson UK, was completed on 26th March and the whole project was conceived, designed, specified and managed by Steve Brayshaw on behalf of Hanson UK and the Wildlife Trust.
Upon its completion, Sand Martins showed an immediate interest and Kim Taylor reported them going in and out of the pipes on 6th April. A week later Cathy Cassie of the Wildlife Trust took this video
Initially the martins showed a preference for the top tier of holes but by 26th April the second tier was also occupied.
Temporary fencing is currently guiding walkers around the northern side of the ramp to minimise disturbance at the new colony, but it is planned to erect permanent gates and fencing across the disused railway line to protect the nesting birds during future breeding seasons.
Many thanks to Steve Brayshaw, habitat creation guru, for providing background and project information and photagraphs and to Barry Boswell www.britishbirdphotographs.com for the kind use of his excellent Sand Martin images.