James Fox in the 2nd edition of Biology and Diseases of the Ferret cites
several studies which found a "lack of a clear-cut diurnal rhythm of
activity" in ferrets.  This contrasts with levels of melatonin in the
blood, which showed a clear pattern (high at night) in one study.  By the
way, diurnal means daily, and can refer to any pattern that occurs on a
day to day basis.
 
One study did show that females on a long night/short day schedule
(non-breeding condition) were active mostly during the day.  When day/night
hours were switched and the females came into heat, they became equally
active at night.  Another study where day/night lengths were about equal
showed no descernible pattern in either males or females, whole or altered.
 
I have not checked the original references for the studies cited, and may
be misinterpreting Fox's interpretation.
 
Linda Iroff
Oberlin, OH
 
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[Posted in FML issue 2685]