Surrey Wildlife Trust has begun a nature conservation project to build a giant 20-metre wide sandcastle for sand martins, tiny 12 centimetre brown and white birds, to welcome them back to nest at a Surrey nature reserve. The huge sand installation will provide hundreds of new sand martin homes at the reserve for the first time in 25 years.

Surrey Wildlife Trust is building the nesting bank, in essence, one enormous sandcastle, with the help of professional sand sculptors, Sand in Your Eye, and landowners Sibelco at Spynes Mere near Redhill. Sand martins, the smallest of Britain's swallow and martin family, visit the reserve annually on their return flight from Africa.

James Herd, project manager at Surrey Wildife Trust, said: ‘

As one of the first spring migrants, sand martins, begin to arrive at Spynes Mere mid-March and feed there until September. But the last time the birds nested at the wetland reserve was 25 years ago. They are sociable birds that gather in large numbers to nest and so the scale of the sand bank will create a sustainable, long term nesting home for a flock of sand martins every year.’

The naturalistic solution is similar to building a sand castle on the beach, just on a grand scale. So the Trust worked with Sand in Your Eye to create several 1.8 metre test sandcastles in mid-January to see if they held up before they began the grand designs Sand Martin bank in February. The build will be complete and ready for nesting mid to late March.

Jamie Wardley, sand sculptor and director of Sand in Your Eye, said:

‘Sand sculpture is beautiful and natural ephemeral land art which blends in with the natural landscape and erodes and disappears over time. So it is a perfect medium for nature conservation. There is a lot of clay in the sand at Spynes Mere, which is really good for helping the sand hold its shape.

‘The sand from the site will be formed into a 20 metre long by 5 metres deep and 1.8 metre high structure made from wooden boards. The sand is then compacted and, after three weeks, the boards can be removed, leaving nature and the sand martins to do the work of sculpting hundreds of nesting burrows.’

The reserve was originally created from a restored sand extraction site, which is part of Nutfield Marshes complex of wetland reserves. Sibelco has supported the conservation project by clearing the bank of scrub on the new nest bank site, as well as, offering extra man-power and machinery for the test builds and main sandcastle build mid February.

Nick Allman, site manager at Sibelco, said: “Sand martins like to nest in active extraction sites because they like the fresh, clean, vertical sand faces. But this can cause problems for Sibelco because if they are found then we have to stop work in that part of the quarry. The sand martin bank is a way of naturally drawing them away from the active sites to where it is safer for them to nest.’

To protect them from predators, sand martins like a vertical face to dig their burrows. Clinging to a tiny ledge, they dig their burrows with their clawed feet. Nesting from mid-March to September, the burrows can be up to 90 centimetres long. At the end of the burrow, four or five eggs are laid on collected straw and feathers in a small chamber.

New vertical faces carved out of the natural sandscape and the nest bank together provide 100 square metres for sand martin homes in total. A metre of the sandbanks will be shaved off the face annually to reduce the risk of nest parasites. After five years the sand can be recycled and rebuilt so it provides a lasting home for the sand martins for the future. The natural sand bank also offers habitat for invertebrates such as solitary bees and wasps.  

The project has been funded by a local growth investment fund, Coast to Capital, as part of the Naturally Richer project, and supported by Chessington World of Adventures Resort’s Chessington Conservation Fund.