The early, development of bar-gnawing was studied in young gerbils kep
t in standard laboratory cages. Bar-gnawing was performed on the bars
of the cage lid and developed shortly after eye-opening at an age of 1
8 days. It increased in bout length and duration with age and there wa
s considerable variability in behaviour between individuals. It is dis
cussed as to whether bar-gnawing is a stereotype and in which behaviou
ral context it develops.