Winter 2001

Bare sand - the naked truth

Article by Lynne Collins, English Nature

Mosaic of bare sand and marram grass on Ainsdale frontal dunes. © English Nature
Many of the plants and animals specific to the sand dunes of the Sefton coast are reliant on bare sand as a component part of their habitat. Here we concentrate on this natural feature and review the importance of bare sand to these species.

Bare sand provides areas for new plants to colonise, places for animals to hunt and scavenge, places to sunbathe and warm up, places to hibernate and pupate, and places to lay eggs.

Euchlora dubia beetle emerging from hole after pupating. © Lynne Collins
The largest areas of bare sand can be found in the frontal dunes where sand blown off the beach is initially deposited. This sand is rapidly colonised by marram grass, Ammophila arenaria, which is so well adapted to this habitat that it requires continuous input of sand for vigorous growth. This growth of marram helps stabilize the frontal dunes and allows other plants to become established.

Huge varieties of animals use the bare sand for a number of reasons. Many invertebrates, such as the Euchlora dubia (=Anomala aenea) (see photo) need areas of bare sand to burrow into for pupating and/or hibernation. Mining bees dig burrows in bare sand, living individually or in small colonies. One species, Colletes cunicularius sub species celticus, is restricted to the north-west England and Wales and only burrows into the south facing slopes of old blow outs. Along with the bees several species of wasp also burrow and nest in the bare sand. The northern dune tiger beetle, Cicindela hybrida, rests in open areas of sand ready to pounce on prey as they are exposed on the bare sand.

Tiger beetle, the Cicindela hybrida, eating a spider. © Rob Wolstenholme
This wealth of invertebrate life often falls prey to the larger predators such as the natterjack toad and the sand lizard. Both species are nationally rare and protected, sand lizards are probably the most threatened reptile in Britain.

Over the past 100 years Natterjack toads have vanished from over 75% of their old sites in Britain, the Sefton Coast remains one of the few strongholds left. Natterjack toads are specially adapted for foraging over bare sand. Known as the running toad, Natterjacks run over open ground to catch their prey. They feed off invertebrates including ground beetles, moths and ants. The toad is quite a powerful digger and digs tunnels into the side of sandy banks for shelter during the day and hibernation over the winter.

Toad in the hole!. © Dan Wrench
The Sefton Coast population of sand lizards is estimated to have declined by over 90%. Only intensive nature conservation efforts mean the population is still present. Areas of open sand play an important role in the lifecycle of this lizard. The sand lizard is Britain's only egg laying lizard. It lays its eggs (4-12 per clutch) in bare sand where they are warmed by the sun until they hatch. Areas of unshaded sand are essential for successful egg incubation. Eggs are not laid too close to vegetation as plants draw moisture out of the sand making it too dry for the eggs to develop. Once hatched, the bare sand also acts as a basking area and a hunting ground for the lizards.

It is important to remember that the mosaics of bare sand and vegetation are an important element of a healthy dune system and must be maintained in a favourable condition. Trampled areas of bare sand, such as beach access points, are of little use to these species as the disturbance is too great. Some areas must be allowed to develop naturally with little or no human disturbance.