Rolf Nussbaumer / Eastern fox squirrel (Sciurus niger) adult on Oak tree (Quercus virginiana) Dinero, Lake Corpus Christi, South Texas, USA.

Rolf Nussbaumer / Eastern fox squirrel (Sciurus niger) adult sitting eating pecan nut in pecan tree, Dinero, Lake Corpus Christi, South Texas, USA.

Edwin Giesbers / Red fox (Vulpes vulpes) looking out from behind tree, captive

Edwin Giesbers / Red fox (Vulpes vulpes) looking out from behind tree, captive

Inaki Relanzon / Fox poison warning sign attached to tree, Great Otway National Park, Victoria State, Australia, September 2011.

George Sanker / Red Fox (Vulpes vulpes) sitting at tree trunk. Shoshone National Forest, Wyoming, USA, May.

Klaus Echle / Young Red Fox (Vulpes vulpes) in a hollow tree. Black Forest, Germany, May.

Klaus Echle / Red Fox (Vulpes vulpes) climbing in tree. Black Forest, Germany, November.

Klaus Echle / Red Fox (Vulpes vulpes) looking up a young tree trunk in misty woodland. Black Forest, Germany, November.

Klaus Echle / Red Fox (Vulpes vulpes) observing from a woodland tree stump. Black Forest, Germany, September.

Klaus Echle / Red Fox (Vulpes vulpes) behind a tree and autumn leaves. Black Forest, Germany, November.

Klaus Echle / Red Fox (Vulpes vulpes) hidden behind a tree trunk and autumn leaves. Black Forest, Germany, November.