Figure 2. Red oak gnawing stick being used for 1,2,4, and 5 months by an adult rhesus macaque. Note the small flakes resulting from gnawing. (Originally published by V. Reinhardt in Laboratory Primate Newsletter 31(2); copyright 1992 by Brown University. Reprinted with permission of Judith E. Schrier, Editor, Laboratory Primate Newsletter.

Figure 2.  Red oak gnawing stick being used for 
 1,2,4, and 5 months by an adult rhesus macaque.  Note the small flakes resulting from gnawing.  
 (Originally published by V. Reinhardt in <EM>Laboratory Primate Newsletter</EM> 31(2); 
 copyright 1992 by Brown University.  Reprinted with permission of Judith E. Schrier, Editor, 
 <EM>Laboratory Primate Newsletter.)
Reinhardt, Viktor. "The Wisconsin Gnawing Stick," Animal Welfare Information Center Newsletter, 7(3):11-12, Winter 1996/1997.