The seventh factor affecting the ability of an animal, such as the ferret,
to become feral it its ability to kill prey animals for food.  Most
predators have instinctual reactions to prey movement, indeed the ferret is
no exception.  Studies have shown ferrets will attempt to capture objects
that move in front of it (cross directions seem to be better than away), and
many react as if the object were prey.  Any cat or dog owner can testify
that this is common enough; it is a shared trait of all carnivores.  But to
be feral, you not only have to eat to survive, you must kill it.  To kill
it, you must capture it.  To capture it, you must be physically capable of
doing so.  To be physically able to capture something, you must recognize
it, know where to search, and how to flush it out.  All these are learned by
ferrets at a very young age, and taught be the mother.  Introductions of the
blackfooted ferret did not first succeed because it was found the released
blackfooted ferrets did not know how to hunt.  Ferrets might capture or kill
the odd animal that wanders in front of it, but that is not a normal state
of events.  Normally, voles and mice attempt to hide or remain motionless
when danger is about.  The hungry ferret, not recognizing the smell of an
animal, is more likely to pass it by than the rodent is to flee.  Even if
the mouse was captured and killed, the ferret still has to recognize it as
food.  Without prior olfactory imprinting, this is unlikely.
 
The eighth factor is the feral animal's ability to combat native diseases.
In the USA, ferrets face a wide range of diseases they did not evolve to
combat, such as local strains of rabies or distemper.  The question of which
specific wildlife diseases could infect and possibly kill ferrets has never
been addressed, but it is logical to assume they would be capable of
contracting most of the diseases that affect the native mustelid
populations.  In the USA and California in particular, this is quite a list.
In the case of canine distemper alone, and because of the length of time it
sheds before the animal dies, there is the potiential probability that a
feral ferret population would die out long before it becomes an
environmental problem.  Some might argue that the territorial nature of the
ferret might prevent such events, but we are speaking of ferrets that have
been pre-conditioned to accept other ferrets as friends.  Additionally,
ferrets would not have to meet each other to spread diseases; they routinely
sniff each latrine area and poop they encounter.  Since territorial
boundaries are marked with poop, and many diseases, such as canine
distempter, can take weeks to kill, shedding most of that time, it is quite
possible that a disease could be spread like a ripple through the entire
community.  Sound farfetched?  Not at all as the wildlife managers
discovered when canine distempter was spread into the last known blackfooted
ferret population, killing nearly 100 individuals and requiring the capture
and containment of the rest.  Interestingly enough, the canine distempter
was probably intorduced by the wildlife scientists in the first place.
Similar events are occuring throughout Africa with lions and wild dogs, to
name a few species negatively impacted by disease.  For further evidence,
ask any American Indian tribe; most current estimates place death by disease
after European contact in the millions.
 
A ninth factor is specific to the ferret, which is female ferrets remain in
heat until they are bred.  If they don't breed, elevated hormone levels
cause blood production to decrease, causing anemia and ultimately, death.
For a population to remain a feral colony, there has to be enough males to
bring the females out of heat, and neutered animals typically cannot perform
the job.  Arguments that state a few animals will breed and ultimately will
founder a large colony ignore this physiological fact.
 
Tenth in the requirements for ferality is the trophic level of the
introduced animal.  The larger the animal, the fewer the predators that will
attempt to consume it.  Feral dogs cannot compete against wolves, they exist
around people.  In that context, excluding humans, there are little if any
predators that can consume them.  Feral cats do better in the wild than
dogs, and are subjected to more predation.  Still, once they make to
adulthood, few other animals bother them, except for dog packs.  Ferrets are
squirrel-sized predators, and have many potiential predators.  They are low
on the trophic level, require lots of movement to establish territories, and
look like native species.  In all cases where ferrets are feral, there is a
singular lack of predation.  This goes without saying in New Zealand, but
even in Britain, feral ferrets are mostly around human habitation where
predators do not typically abound; besides, most larger predators in Britain
have reduced populations due to human control.
 
The eleventh reason is predation vulnerability.  Pet ferrets don't recognize
they are in danger, and may even approach a predator out of curiosity.  The
typical response of a pet ferret to something unknown and possibly dangerous
to to freeze, stare, and sniff.  Wild polecats flee.  The first time a lost
ferret meets a mink or fox, it will become dinner, and as such, has a hard
time contributing to the feral populations.
 
The last factor I will discuss in detail is the history of extinctions,
introductions, and radiations for the particular region.  Do animals often
succeed, or are most introductions temporary, with no more than a local
impact?  In the case of California, which animals live in a feral state
completely, which live in a feral state with additional introductions, and
which cannot or have not been able to make a feral transition?  Known to be
completely feral (with hunting regulated by the California Fish and Game)
are wild boar, several species of trout, and pheasant.  Known to be
completely feral and either not regulated or protected are horse, burros,
goats, sheep, cows, house mice, brown rats, black rats, nutria, rabbits,
fallow deer, sika deer, chickens, geese, the African clawed toad, many
species of fish, quail, finches, pigeons, and parakeets.  Known to be feral,
but probably depending on recruitment to maintain colonies are dogs and
cats.  Suspected to have small feral populations are cavies and hamsters.
(This list is not inclusive and only reflects the more common animals) In
the history of feral animals in California and the USA, ferrets are
mentioned but never proven, anywhere and at any time.  Populations of
ferrets living near or around ferret farms is unsubstantiated.  The Ohio
(Ferretown) feral population is nonexistent.  The populations living on the
San Juan Islands died out, as reported by the state of Washington.  Ferrets
came over with the first sailing ships, and have been in the country for
more than 200 years.  In the last century, they were quite commonly used to
rid barns and other places of rats, and were promoted by the US government
for such purposes.  In California, ferrets were raised and used to control
rats and other vermin.  In all that time, with decades of accidental and
intentional releases, there is not a single feral ferret colony that can be
scientifically proven and recorded.  Historically, the ferrets released or
lost were sexually viable and ate foods very similar to the native species,
and they couldn't form feral populations.  So if history has proven ferrets
capable of breeding and hunting could not create feral populations, how can
the California Fish and Game suggest neutered, kibble-fed, cage-raised
animals can?
 
Next Installment: Domestic Issues
 
Bob C and the 18 Dirty Ratters (Missing Gus)
[Posted in FML issue 1763]