Proximate and ultimate perspectives on imprinting in graylag geese.
   BEHAVIOR: Young geese follow and imprint on their mother.

   PROXIMATE  CAUSE:  During  an early, critical developmental stage, the
   young geese observe their mother moving away from them and calling.

   ULTIMATE  CAUSE:  On  average,  geese that follow and imprint on their
   mother  receive  more care and learn necessary skills, and thus have a
   greater  chance  of  surviving  than  those  that  do not follow their
   mother.