BTW, crepuscular is typically considered a SUBSET of nocturnal, so when
there is not the refinement done that is what papers will say, so you
will find both, yes. Also when unable to be active enough at dawn at
dusk (Notice those are the times of MOST activity, not ALL activity.)
there is a preference for night activity to make up the needs. If that
doesn't work they will be active in the day.

People here in the U.S. will be more familiar with that same pattern
among raccoons which are most active in low light conditions that are
hard on our eyes, tend to be active but less so also at night, but if
the conditions have been bad -- say storming at night or during a time
when food supplies are lower than needed or babies made it impossible
for mom to forage for a while -- then they will come out at day to fill
their needs.

Anyway, crepuscular does *NOT* mean that the animals are strictly only
active then; it means that subset of nocturnal activity is when the
animals are typically most active. It's a pretty good time, though it
has its hazards from other species that also exploit its good points.
There are several larger prey species which are slowing down. Some
smaller prey species like frogs are announcing themselves so easier to
find. The cooling is slowing down some reptiles which can pose dangers
such as snakes, the low light conditions are not optimal for multiple
birds of prey. You get the idea.

Notice that the terms only refer to usual times of most activity. There
is flexibility in there when needed and that flexibility is used. Heck,
humans are diurnal, but how much do you get done at other times, even
without lighting?

Sukie (not a vet)
Current FHL address:
http://groups.yahoo.com/group/ferrethealth
Recommended ferret health links:
http://pets.groups.yahoo.com/group/ferrethealth/
http://ferrethealth.org/archive/
http://www.afip.org/ferrets/index.html
http://www.miamiferret.org/fhc/
http://www.ferretcongress.org/
http://www.trifl.org/index.shtml
http://homepage.mac.com/sukie/sukiesferretlinks.html

[Posted in FML 5545]