Shirley:

The technical definition is that the times of greatest activity are low
light times.

Bob's additional points were these:

1. Although crepuscular is clumped in with "nocturnal" it does refer to
"between" times which are not night or day so could as easily have been
otherwise clumped (but most crepuscular animals go for activity in
darkness when they can't complete their activities in low light period,
rather than activity in light which, if memory serves, is why that
clumping was original used).

2. Being crepuscular means being FLEXIBLE. It's not part of the
"definition" but it is part of the behavior -- more of a generalizing
behavior in terms of times of activity. A crepuscular animal can (and
often does) utilize the night time hours, too, vastly more than a
diurnal (most activity in daylight) animal typically does (with the
exception of Bill Gruber but he uses lights so he cheats ;-) ). ALSO,
a crepuscular animal utilizes the daytime hours if it couldn't get
things done otherwise more than a strictly nocturnal (most activity
in daylight) animal will.

So, it does NOT mean that the animals are active all the time. It means
that the wild species PREFER LOW LIGHT TIMES FOR ACTIVITY ***BUT*** IF
THEY NEED TO DO SO THEY ARE FLEXIBLE ENOUGH TO EXPLOIT OTHER TIMES.

I don't know what an Australian example is, but here in the U.S. the
raccoon is a great example. Given its druthers the raccoon will forage
most in low light hours. If it can't manage to do enough then, well,
it will continue into the night. If even that doesn't work well enough
(for example, if the weather prevented activity) then the raccoon will
also be active in the daylight hours. All to often I have heard people
say, "I saw a really sick raccoon." and when I asked what the symptoms
were the person would reply, "It was out in the daylight." Huh? By
itself that just means that the weather was too bad, the food too
scarce, or something else prevented foraging at preferred times. Yes, I
know I have given this example before, but it is one people around here
can relate to. On reading it I suspect that many people elsewhere will
say, "Oh! That is like such-and-such animal." while naming something
local.

Now, try imagining a totally diural animal exploiting a dark night, or
a totally noctural animal exploiting bright daylight. It can happen but
is much less likely to happen and far less likely to happen safely or
effectively, because rather than being generalists in terms of the
light conditions they can use they are adapted in a way that can be
exclusionary.

So, being able to do something doesn't mean that it is preferentially
done, but that it is an option when needed for the wild species.

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 5551]