Just a quick note on mink as pets.  They can be quite friendly, even
affectionate if hand-raised; that is taken from the mother and bottle-fed.
They will bond to you as a child bonds to a parent.  But there are four
major problems.  First, NEVER expect them to respnd to others as they do to
you.  They will be "unreliable" in behavior towards others; even aggressive
at times.  Second, NEVER expect them to forget they are a mink.  They will
always rather live in an unconfined state.  (I heard a rumor mink were
moving from California for that very reason...) If you think ferrets dig and
scratch.... Third, they will likely be destroyed if they should harm anyone
at anytime, including the infliction of minor scratches.  Just look at the
problems we have with ferrets in such situations, and only the
scientifically stupid argues that they are not domesticated.  Fourth, they
are a wild animal in a tamed condition, which means they have the same
behaviors as wild mink, only modified by conditioning.  Ferrets have been
bred for behavior for centuries, and have domesticated behavior.  The two
are quite different.  Yes, wild fitch do act like wild animals, BUT when
compared to polecats, they have distinct behavioral differences directly
related to domestication.  I've had a pet mink, and have several friends who
have them.  They are a special challenge that you will have to live with for
a decade or so; one that gets worse over time as they get older and start
acting more mink-like.  They are beautiful, but I can't recommend them to
most people.
 
I was recently asked why male ferrets are so much larger than female
ferrets.  I have several males that are twice as large and three times
heavier than females.  This phenomenon is called "Sexual Dimorphism," and
occurs in most species to one degree or another.  Sometimes, the females are
larger--some birds, spiders, etc., but in most sexually dimorphic mammals,
the males are larger than the females.  The reasons for this are varied, but
three of them are the most likely to mammals in general, and one in the case
of the polecat and ferret.
 
One reason is sex.  The biggest guy gets the girl, so big guys produce more
offspring compared to little guys.  This works to a degree--until the limits
of the niche are met--otherwise animals would only get bigger and bigger.
And it doesn't explain why females remain small.  That reason is the second
reason; that is, the bigger guys have to eat more to remain healthy.  You
have to eat alot when you are big to maintain the body; its worse when you
are a predator and have to raise babies.  So smaller females have an
advantage, and can successfully raise more offspring than the larger
females.  These two reasons alone helps explain why so many mammalian
carnivores are sexually dimorphic.  But they are not the only, nor the most
important reasons.
 
In some solitary hunting animals such as the polecat, sexual dimorphism
seems to be more related to niche specialization than to the other two
reasons.  When you read what a predator eats, it is rarely divided into
male-preferred and female-preferred foods.  Male polecats exclude other
males from their territory, and females ferrets exclude females.  But they
will overlap and share territories with each other.  How can they and still
get enough to eat, much less raise offspring?  One of the few hard and fast
rules of biology is that you can only have one species/type/whatever per
niche.  If you have more than one, only one will remain over time.  The rest
will move, change niches, or go extinct.  This is significantly true with
predators-each one has a specific location, hunting style or time, prey.
etc., when compared to others.
 
Polecats can do it because the females tend to go after smaller prey than
males.  For example, both males and females can go down rabbit burrows, but
females can also go down the burrows of smaller animals, such as rats and
voles.  So the males tend to hunt more rabbits and the females tend to hunt
smaller rodents (although I'm sure neither would turn their noses up at
either, we are speaking of overall trends, not occasional specifics).  While
polecats as a whole fill a specific niche, the niche is subdivided between
males and females.  Males fill the same part, so they are exculded from
territories, but females are in a slightly different niche, so they are
allowed.
 
All three reasons are important, but the last one is thought to be the most
important to polecats in general, and mustelids as a whole.  (BTW, mustelids
tend to be one of the most sexually dimorphic group of mammals, and are only
surpassed by sealions and other penipeds in the degree of dimorphism
exhibited.) Supporting evidence is seen in territorial animals in which ALL
other members, regardless of sex, are excluded.  In these animals, body size
is about the same, or if sexual dimorphism exists, it is relatively minor in
nature.  The same is true of cooperative hunters, such as some mongoose and
fox species.  Yes, the males are slightly larger, but not markedly so.
 
No one knows exactly why polecats are so sexually dimorphic, but the three
reasons given are certainly at the top of the list.  Ferrets are sexually
dimorphic because they are essentially domesticated polecats, and still
exhibit this powerful genetic trait.  Oh yeah, it is true that SOME males
are smaller than SOME females.  This is because the body size of both males
and females form a continuum that overlaps the other.  There will always be
individuals what are smaller or larger than normal.
 
Bob and the 13 Dimorphin' Rangers
[Posted in FML issue 1489]