Fabrice Cahez / Eurasian Sparrowhawk (Accipiter nisus) rear view perching on fence post with tail feathers spread. Vosges, France, January.

Fabrice Cahez / Roe Deer (Capreolus capreolus) jumping over barbed wire fence in snow. Vosges, France, January.

Ross Hoddinott / Male house sparrow (Passer domesticus) on barbed wire fence, next to starlings (Sturnus vulgaris). Nr Bradworthy, Devon, UK, December

Charlie Summers / Rocky Mountain Bighorn sheep (Ovis canadensis) female jumping barbed wire fence, Montana, USA

Andy Sands / European Cuckoo (Cuculus canorus) female perched on fence post, Isle of Coll, Scotland, UK, June

Nick Garbutt / Polar Bear Cub (7-8 months) (Ursus maritimus) investigating photographer through wire fence. Lodge on the shores of Hudson Bay, Canada (Sept).

Nick Garbutt / Polar Bear Cubs (7-8 months) (Ursus maritimus) investigating photographer through wire fence. Lodge on the shores of Hudson Bay, Canada (Sept).

Luke Massey / 2020VISION / Turtle dove (Streptopelia turtur) perched on a barbed wire fence in a rain shower, Essex, England, UK, June.

Eric Medard / Common buzzard (Buteo buteo) flying over wire fence in winter, France, February

Eric Medard / Common buzzard (Buteo buteo) trapped on a barbed wire fence, France, July

Eric Medard / Common buzzard (Buteo buteo) trapped on a barbed wire fence, France, July

Eric Medard / Common buzzard (Buteo buteo) trapped in a barbed wire fence, France, July

David Tipling / 2020VISION / Skylark (Alauda arvensis) perched on fence post, Cambridgeshire Fens, UK, April

Markus Varesvuo / Two Turtle doves (Streptopelia turtur) on barbed wire fence, Israel, May

Martin Willis / Red-backed Fairywren (Malurus melanocephalus) female with insect, Atherton Tableland, Queensland, Australia

Martin Willis / Masked Finch (Poephila personata), Cumberland Dam, western Queensland, Australia

Ernie Janes / Barn swallow (Hirundo rustica) perched on barbed wire fence, UK, June

Robin Chittenden / Woodchat shrike (Lanius senator) perched on wire fence, La Serena Steppes, Badajoz, Extremadura, Spain, March

Robin Chittenden / Sand martins (Riparia rioaria) perched on wire fence, Cley NWT, Norfolk, UK, July

Andrew Parkinson / Wood pigeon (Columba palambus) feathers ruffled, perched on a rusty wire fence, Gloucestershire, UK, October.

Jean E. Roche / Skin of Wild boar (Sus scrofa) left out to dry on wire fence and post, Corsica, France, September 2010

Gary K. Smith / Domestic cattle (Bos taurus) looking over barbed wire fence. Norfolk, UK, May.

Charlie Summers / Western Kingbird (Tyrannus verticalis) perched on a barbed wire fence. Colorado, USA, May.

Chris Gomersall / 2020VISION / Grasshopper warbler (Locustella naevia) adult perched on fence post, singing in reedbed, Norfolk, UK, May

Paul Hobson / Short eared owl (Asio flammeus) perched on wire fence in snow, UK, January 2011

Ann & Steve Toon / Pearl spotted owlet (Glaucidium perlatum) perched on fence post at night, Kgalagadi Transfrontier Park, South Africa, November

Ingo Arndt / Flying Fox (Pteropus sp) caught in barbed wire fence, Queensland, Australia

Brent Stephenson / Fledgling Welcome Swallows (Hirundo neoxena) huddled together on a wire fence waiting to be fed. Wenderholm Regional Park, Auckland, New Zealand, December.

Brent Stephenson / Adult Welcome Swallow (Hirundo neoxena) feeding fledglings perched on a wire fence. Wenderholm Regional Park, Auckland, New Zealand, December.

Brent Stephenson / Fledgling Welcome Swallows (Hirundo neoxena) huddled together on a wire fence waiting to be fed. Wenderholm Regional Park, Auckland, New Zealand, December.

Brent Stephenson / Fledgling Welcome Swallows (Hirundo neoxena) huddled together on a wire fence waiting to be fed. Wenderholm Regional Park, Auckland, New Zealand, December.

Brent Stephenson / Adult Welcome Swallow (Hirundo neoxena) feeding fledglings perched on a wire fence. Wenderholm Regional Park, Auckland, New Zealand, December.

Brent Stephenson / Adult Welcome Swallow (Hirundo neoxena) feeding fledglings perched on a wire fence. Wenderholm Regional Park, Auckland, New Zealand, December.

Brent Stephenson / Fledgling Welcome Swallows (Hirundo neoxena) huddled together on a wire fence waiting to be fed. Wenderholm Regional Park, Auckland, New Zealand, December.

Brent Stephenson / Fledgling Welcome Swallows (Hirundo neoxena) huddled together on a wire fence waiting to be fed. Wenderholm Regional Park, Auckland, New Zealand, December.

Brent Stephenson / Fledgling Welcome Swallows (Hirundo neoxena) huddled together on a wire fence waiting to be fed. Wenderholm Regional Park, Auckland, New Zealand, December.

Peter Cairns / Scottish Wildcat (Felis sylvestris) strung up on wire fence - shot close to pheasant shoot, Scotland, UK. STAGED IMAGE. December 2006

Peter Cairns / Scottish Wildcat (Felis sylvestris) strung up on wire fence - shot close to pheasant shoot, Scotland, UK, STAGED IMAGE, December 2006

Peter Cairns / Scottish Wildcat (Felis sylvestris) strung up on wire fence - shot close to pheasant shoot, Scotland, UK, STAGED IMAGE, December 2006

Peter Cairns / Scottish Wildcat (Felis sylvestris) strung up on wire fence - shot close to pheasant shoot, Scotland, UK, STAGED IMAGE, December 2006

Ross Hoddinott / Kestrel (Falco tinnunculus) female resting on the post of a barbed wire fence (captive). Nr Haytor, Dartmoor, UK, November

Ross Hoddinott / Kestrel (Falco tinnunculus) female resting on the post of a barbed wire fence (captive). Nr Haytor, Dartmoor, UK, November

Ross Hoddinott / Male house sparrow (Passer domesticus) on barbed wire fence in farmland. Nr Bradworthy, Devon, UK, December

Fergus Gill / Twite (Carduelis / Acanthis flavirostris) resting on a barbed wire fence. Isle of Berneray, Outer Hebrides, Scotland, August

Fergus Gill / Twite (Carduelis / Acanthis flavirostris) resting on a barbed wire fence. Isle of Berneray, Outer Hebrides, Scotland. August

Nick Upton / Migrant male Red-backed shrike (Lanius collurio) perched on barbed wire fence. Lesbos / Lesvos, Greece, August.

Nick Upton / Immature Red-backed shrike (Lanius collurio) perched on wire fence. Lesbos / Lesvos, Greece, August.

Charlie Summers / Rocky Mountain Bighorn sheep (Ovis canadensis) ram with full curl horns, jumping barbed wire fence, Montana, USA

David Welling / Botteri's Sparrow (Aimophila botterii) perched on barbed wire fence, Near Laguna Atascosa National Wildlife Refuge, Texas, USA, May

Ernie Janes / Domestic cattle, close up of nose of Jersey dairy cow under strand of barbed wire, in summer pasture, UK, June 2005

Markus Varesvuo / Corn Bunting (Miliaria / Emberiza calandra) perched on barbed wire fence, Spain, September

Markus Varesvuo / Two Corn Buntings (Miliaria / Emberiza calandra) perched on barbed wire fence, Spain, September

Andrew Parkinson / Stonechat (Saxicola torquatus) male perched on a frost covered fence post. Dumfries and Galloway, Scotland, UK. December. (non-ex)

Andrew Parkinson / Redstart (Phoenicurus phoenicurus) male perched on a barbed wire fence during autumn migration. Norfolk, UK, September (non-ex)

Andrew Parkinson / Redstart (Phoenicurus phoenicurus) perched on a barbed wire fence during autumn migration. Norfolk, UK, September (non-ex)

Alan Williams / Female Wheatear (Oenanthe oenanthe) sitting on fence post, Denbigh Moors, North Wales, UK, April 2010

Andy Sands / Pied wagtail (Motacilla alba yarrellii) adult perched with insect prey on wire fence, Isle of Coll, Scotland, UK, June

Pete Oxford / White-headed Marsh-Tyrant (Arundinicola leucocephala) male on barbed-wire fence, Rupununi, Guyana

Gerrit Vyn / Western Kingbird (Tyrannus verticalis) perched on wire fence. Southeast Alberta, Canada. May.

Gerrit Vyn / Vesper Sparrow (Pooecetes gramineus) perched on fence. Southeast Alberta, Canada. May.

Alan Williams / Young male Kestrel (Falco tinnunculus) perching on roadside fence post, Yorkshire, UK, July.

Gerrit Vyn / Adult male American Kestrel (Falco sparverius) hunting from a barbed wire fence. Gunnison County, Colorado, USA, April.

David Kjaer / House sparrow (Passer domesticus) male and female perched on wire fence, North Uist, Outer Hebrides, Scotland, May

Chris Gomersall / Quail (Coturnix coturnis) killed in collision with barbed wire fence, Island of South Uist, Outer Hebrides, Western Isles, Scotland

Steven Kazlowski / Yellow-headed blackbird (Xanthocephalus xanthocephalus) on a wire fence, National Bison Range Wildlife Refuge, Montana, USA.

Steven Kazlowski / Western meadowlark (Sturnella neglecta) singing on barbed wire fence, National Bison Range Wildlife Refuge, Montana, USA.

Albert Lleal / Sewage and shacks in Dhaka slum, Bangladesh

Stephen Dalton / Wall lizard (Lacerta muralis) sunning on fence post, Italy

Roger Powell / Red rumped swallow (Cecropis saurica) perched on a barbed wire fence during rain on migration, Evora, Portugal

Warwick Sloss / Great tit (Parus major) perching on barbed wire fence, winter, Somerset, UK

Mark Moffett / Argentine Ant (Linepithema humile) group on barbed wire, Argentina

Alan Williams / Corn bunting (Miliaria calandra) singing on barbed wire fence in farmland, Essex, UK, April

Donald M. Jones / White-tailed Deer (Odocoileus virginianus) buck going under barbed wire fence, western Montana. Sequence 2 of 2

Donald M. Jones / White-tailed Deer (Odocoileus virginianus) hair on a barbed wire fence, western Montana

Donald M. Jones / White-tailed Deer (Odocoileus virginianus) buck going under barbed wire fence, western Montana. Sequence 1 of 2

Donald M. Jones / White-tailed Deer (Odocoileus virginianus) buck jumping barbed-wire fence, western Montana

Donald M. Jones / White-tailed Deer (Odocoileus virginianus) buck jumping barbed-wire fence, western Montana

Donald M. Jones / White-tailed Deer (Odocoileus virginianus) buck jumping barbed-wire fence, western Montana

Donald M. Jones / Bobolink (Dolichonyx oryzivorus) male singing on barbed wire fence, western Montana

Wild Wonders of Europe / Nill / Five Common sparrows (Passer domesticus) perched on a wire fence, Bulgaria, May 2008

Dave Bevan / Corn bunting (Miliaria /Emberiza calandra) perched on barbed wire fence, singing, UK

Donald M. Jones / Short-eared Owl (Asio flammeus) on fence post, western Montana

Donald M. Jones / Mountain Bluebird (Sialia currucoides) male on barbed wire fence, western Montana

Donald M. Jones / Lark Sparrow (Chondestes grammacus) sitting on barbed wire fence, western Montana

Andy Sands / Yellow Wagtail (Motacilla flava flavissima) male singing from barbed wire fence, Upper Teesdale, Co Durham, England. UK

Andy Sands / Yellow Wagtail (Motacilla flava flavissima) male perched on barbed wire fence, Upper Teesdale, Co Durham, England. UK

Scott Leslie / Alder Flycatcher (Empidonax alnorum) perching on wire fence, Nova Scotia, Canada

Scott Leslie / Alder Flycatcher (Empidonax alnorum) perching on wire fence, Nova Scotia, Canada

David Kjaer / Corn Buntings (Miliaria calandra) and Yellowhammers (Emberiza citrinella) sitting on barbed wire fence, spring, Wiltshire, England

David Kjaer / Male Yellowhammer (Emberiza citrinella) sitting on barbed wire fence, in spring, Wiltshire, England

David Kjaer / Corn Buntings (Miliaria calandra) on barbed wire fence, spring, Wiltshire, England

Miles Barton / Inland Bearded Dragon (Pogona vitticeps) adult on barbed wire fence at farm in Hawker, Flinders Ranges, South Australia

David Kjaer / Corn Bunting (Miliaria calandra) sitting on barbed wire fence singing, Wiltshire, England

Ingrid Visser / Domestic Horse (Equus caballus) four ponies standing at barbed wire fence, Westman Islands, Iceland

Jose B. Ruiz / Domestic cat {Felis catus} looking through wire fence, Picos de Europa, Asturias, Spain