Jose B. Ruiz / Red trunks of Cork Oak trees which have been stripped of bark(Quercus suber) Las Hurdes, Caceres, Spain

Chris O'Reilly / Red oak {Quercus rubra} close-up of leaf showing autumn colour change, UK, Sequence 3/3

Mark Moffett / Northern Red Oak (Quercus rubra) tree with corns and leaves at base, Massachusetts

Mark Moffett / Northern Red Oak (Quercus rubra) tree with corns and leaves at base of it, Massachusetts

Doug Wechsler / Close-up of Blackjack oak (Quercus marilandica) leaf close up changing colour, Pinelands Reserve, New Jersey, USA, October.

Doug Wechsler / Close-up of Blackjack oak (Quercus marilandica) leaf close up changing colour, Pinelands Reserve, New Jersey, USA, October.

Doug Wechsler / Close-up of Blackjack oak (Quercus marilandica) leaf close up changing colour, Pinelands Reserve, New Jersey, USA, October.

Colin Varndell / English oak tree (Quercus robur) close up of twig in winter showing buds, Dorset, UK January.

Dr. Axel Gebauer / Red panda (Ailurus fulgens) use this oak tree as latrine, Pangolakha Wildlife Sanctuary, Sikkim, India

David Woodfall / Sessile Oak tree (Quercus petraea) sapling planted in plastic tube to protect from sheep, amongst Bluebells and Red campion in woodland previously deforested, UK

David Woodfall / Sessile Oak tree (Quercus petraea) sapling planted in plastic tube to protect from sheep, amongst Bluebells and Red campion in woodland previously deforested, UK

Adrian Davies / Tree Lungwort (Lobaria pulmonaria) growing on oak bark. Red parts are spore releasing bodies. The Trossachs, Scotland, February.

Adrian Davies / Tree Lungwort (Lobaria pulmonaria) growing on oak bark. Red parts are spore releasing bodies. The Trossachs, Scotland, February.

Adrian Davies / Tree Lungwort (Lobaria pulmonaria) growing on oak bark. Red parts are spore releasing bodies. The Trossachs, Scotland, February.

Solvin Zankl / Subadult Eurasian red squirrel (Sciurus vulgaris) head portrait, feeding with paws, Germany

Stephen Dalton / Red admiral butterflies (Vanessa atalanta) on oak tree, sipping oak sap, UK

Stephen Dalton / Red admiral butterflies (Vanessa atalanta) on oak tree, sipping oak sap, UK

Scott Leslie / Northern Red Oak (Quercus rubra) along Mersey River, Kejimkujik National Park, Nova Scotia, Canada

Yva Momatiuk & John Eastcott / Oak (Quercus sp) leaves and Single-leaf Pinyon Pine (Pinus monophylla) trees in first snow, Great Basin National Park, Nevada

Philippe Clement / Scarlet oak (Quercus coccinea) leaf in autumn colours, native to North America

Philippe Clement / Northern red oak (Quercus rubra) leaves in autumn colours, native to North America

Philippe Clement / Fallen Northern red oak leaves (Quercus rubra) on forest floor in autumn, Belgium

Philippe Clement / Southern red / Spanish / Swamp red oak (Quercus falcata) leaves in autumn colours, native to the southeastern United States

Philippe Clement / Northern red oak / Champion oak (Quercus rubra) leaf in autumn colours, native to North America

Philippe Clement / Fallen Northern red oak leaves (Quercus rubra) on forest floor in autumn, Belgium

Philippe Clement / Southern red / Spanish / Swamp red oak (Quercus falcata) leaves in autumn colours, native to the southeastern United States

Bruno D'Amicis / Red squirrel (Sciurus vulgaris) looking down from Oak tree (Quercus robur) in autumn, Berlin, Germany

Bruno D'Amicis / Red squirrel (Sciurus vulgaris) looking down from Oak tree (Quercus robur) in autumn, Berlin, Germany

Jerry Monkman / Northern Red Oak tree {Quercus rubra} in early summer, Sandwich, New Hampshire, USA

Roger Powell / Red-berried southern Mistletoe {Viscum coloratum} growing on host tree of Portuguese Oak (Quercus faginae) Sierra de Grazalema, Andalusia, Spain

Edwin Giesbers / Red deer (Cervus elaphus) stag under large spreading oak tree, Dyrehaven, Denmark

Jose B. Ruiz / Red trunks of Cork Oak trees which have been stripped of bark (Quercus suber) Las Hurdes, Caceres, Spain

Jose B. Ruiz / Close up of red trunk of Cork Oak tree where bark has been stripped (Quercus suber) Caceres, Spain

Jose B. Ruiz / Close up of red trunk of Cork Oak tree (Quercus suber) which has been stripped of bark, Las Hurdes, Caceres, Spain

Jose B. Ruiz / Looking up the red trunk of a Cork Oak tree which has been stripped of its bark (Quercus suber) Las Hurdes, Caceres, Spain

Bernard Castelein / Close up of veins in leaf of Red oak tree {Quercus rubra} Belgium

Bernard Castelein / Fallen leaf of Red oak tree {Quercus rubra} amongst leaf litter, Belgium

Bernard Castelein / Fallen leaf of Red oak tree {Quercus rubra} Belgium

Paul Hobson / Red Kite {Milvus milvus} adult sitting in oak tree, Wales, UK

Chris O'Reilly / Red oak {Quercus rubra} close-up of leaf showing autumn colour change, UK, Sequence 1/3

Chris O'Reilly / Red oak {Quercus rubra} close-up of leaf showing autumn colour change, UK, Sequence 2/3

Chris O'Reilly / Red oak (Quercus rubra) leaf showing autumn colours. UK

Bernard Castelein / Red Oak (Quercus rubra) leaf close up, changing colour, Belgium

Philippe Clement / Red deer hind standing on hind legs to browse on Oak tree {Cervus elaphus}, Jaegersborg, Denmark

Konrad Wothe / English Oak (Quercus robur) tree in snow, Bavaria, Germany

Philippe Clement / Northern red oak leaves {Quercus rubra} in autumn, Belgium

Philippe Clement / Northern red oak trees {Quercus rubra} leaves changing colour in autumn, Belgium

Philippe Clement / Northern red oak leaves {Quercus rubra} in autumn, Belgium

John Cancalosi / Red deer standing to browse on Oak tree {Cervus elaphus} UK.

Flip de Nooyer / English Oak (Quercus robur) in autumn, Europe, Asia and north Africa introduced into North America. Sequence 1 of 4

Flip de Nooyer / English Oak (Quercus robur) in autumn, Europe, Asia and north Africa introduced into North America. Sequence 2 of 4

Flip de Nooyer / English Oak (Quercus robur) in autumn, Europe, Asia and north Africa introduced into North America. Sequence 3 of 4

Flip de Nooyer / English Oak (Quercus robur) in autumn, Europe, Asia and north Africa introduced into North America. Sequence 4 of 4

Tim Fitzharris / Poison Oak (Toxicodendron diversilobum) on Monterey Pine (Pinus radiata) bark, Pt Lobos, California

Mark Moffett / Northern Red Oak (Quercus rubra) tree with corns and leaves at base of it, Myles Standish State Forest, Massachusetts