Marie Read / Blue jay (Cyanocitta cristata) holding an acorn in its bill whilst perched on tree stump, with autumn foliage, New York, USA, October.

SCOTLAND: The Big Picture / Red squirrel (Sciurus vulgaris) descending trunk of Oak tree, Cairngorms National Park, Highlands, Scotland, UK, October 2015.

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

Bernard Castelein / American oak (Quercus rubra) trees in avenue, sun shining through. Peerdsbos, Brasschaat, Belgium. November 2013.

Andy Sands / English oak tree (Quercus robur) Split in dead trunk showing red deadwood inside trunk this is a very important habitat of ancient trees for saproxylic insects, London, England, UK, November

Philippe Clement / Low angle shot of a Red oak tree (Quercus rubra) showing leaves in autumn colours, October, Belgium.

Philippe Clement / Low angle shot of a Red oak tree (Quercus rubra) showing leaves in autumn colours, October, Belgium.

Philippe Clement / Low angle shot of a Red oak tree (Quercus rubra) showing leaves in autumn colours, October, Belgium.

Nick Hawkins / Red oak (Quercus rubra) low angle view of trees, New Brunswick, Canada, May.