6 November 2015

The hidden world within a dry stone wall



Assistant Ranger, Julie Bell delves into the hidden world within a dry stone wall.  Not just a functional stock-proof boundary; they hide an entire wild community who live alongside and within this man-made structure. 

Walling within the South Lakes area

Come to the South Lakes and you can’t help but notice the dry stone walls that form such strong patterns and field boundaries within the landscape, criss-crossing through the pastoral valleys, and up onto the high fells.  

I love how they stand as testament to the skill and hard-work of our forebears, built from natural, locally sourced materials (slate, granite, sandstone or limestone), with no fuels or imports.  The ultimate sustainable build!  

Fields beside Esthwaite Water (©National Trust Images/Joe Cornish)

Living walls

At first glance, it may appear that dry stone walls are a barren, hostile environment for wildlife.  Take a closer look - you will see these living walls are a haven for wildlife, providing important sanctuary to many plant communities, birds, mammals and insects.   Dry stone walls also provide important shelter for larger mammals too in severe weather conditions – hill sheep, and us humans!  

The first residents move in

Whilst the stone gives a wall its strength, age gives it character.  Over time, weathered stone becomes porous.  This allows the first residents to move in: an extraordinary plant, with the ability to grow where no other plants have gone before - the lichens.  Did you know: the age of a wall can be guessed from the spread of lichen.  Another pioneering plant, the mosses, are soon to follow behind the lichens. 

Lichens on a wall weathered by wind and rain. 


The flowers arrive

Once these pioneering plants have gained a secure foothold, the flowers arrive.  Seeds of annuals such as dandelions and herb Robert - a familiar flower on banks and hedgerows - land on the wall, carried in by drifting in the wind, or by ants.


Creepy crawleys

There are many insects harboured within a wall’s cracks and crevices, including spiders, woodlice, springtails, millipedes, snails, bees, and wasps. 

Did you know: snails are surprisingly long-lived and may roam the same patch on a wall for up to six years? 

Common woodlouse on moss


Mammals

A variety of mammals make use of walls as a place of shelter, for feeding, nesting, and as a protected corridor to move between different areas of favourable habitat.   These include:

Hedgehog
  • Slow worms
  • Common lizards
  • Adders
  • Toads
  • Frogs
  • Voles
  • Field mice
  • Shrews
  • Hedgehogs 
  • Red squirrels – known to store nuts under the stones.

Birds

Birds are frequent visitors to a dry stone wall, using them as a place to search out possible meals, a place to nest, or as shelter or a roost. 

The secretive Wren
Wrens occupy holes in walls as nests and also for winter shelter.  They lose heat rapidly when not active in colder weather and Wrens will huddle together for warmth.

Other birds that sometimes nest in walls are blue and great tits, pied and grey wagtails, house and tree sparrows, spotted flycatchers, nuthatches and wheatears.  One bird that favours walls for nesting is the Redstart. 


Take a look for yourself

So, next time you find yourself beside a dry stone wall, take a closer look around you.  You may just be surprised to discover the sheer variety of life you will find.

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