One of the greatest problems in the California ferret debate is the circular
reasoning popular with the Fish and Game wardens.  In a circular argument,
"A" relates to "B" and "B" relates to "C" so "A" is assumed to relate to
"C." Superficially, this looks good, but think about it.  You would never
believe that because asses have ears, and ears are also on California Fish
and Game wardens, that California Fish and Game wardens are asses, would
you?  Well, at least not because of the ears.  Yet this is precisely the
type of reasoning used in the Constantine and Kiser report to prove ferrets
can become feral and cause environmental destruction.
 
For example, ferrets are feral in New Zealand, and some animal species have
gone extinct on New Zealand since the introduction of ferrets, so obviously,
feral ferrets cause extinctions.  This is just like saying, I have a
sandwich.  It is a ham sandwich.  Since you have a sandwich, it must also be
ham.  You simply cannot assume two seemingly interconnected phenomenon are
correlated until the relationship is proven.  In the case of ferrets in New
Zealand, the relationship in not proven.
 
What are some of the factors associated with sucessful ferality?  Quite
simply, they are the exact same requirements for any species to radiate into
a new area; the rules of nature apply to all equally, regardless of state of
domestication.  The first, and perhaps the most important, is the niche.
Unless the new animal can find a niche suited to its body and physiology, it
cannot survive.  It is simply inconceivable that a mountain beaver can
survive in the desert, or a kangaroo rat in the tundra.  In the case of the
domesticated ferret, there are some areas in California that could
theoretically be inhabited by feral populations.
 
A second factor is either an open niche, or a niche that can be taken over
from a competitor.  In New Zealand, the niche was almost completely open for
the ferret (and other predators).  In Britain and parts of Europe, the niche
is also at least partially open because of the local destruction of
polecats.  These conditions do not exist in California.  In areas that could
support ferrets, the niches are already filled with a locally evolved
mustelid, the mink, which has proven its competitive abilities to be
superior to both the polecat and the ferret.  In Britain and Europe,
polecats usually lose ground to the American mink, but in a few instances,
they have fought to a standstill with both modifying their niche to reduce
competition.  Both animals are far better predators than the ferret.  It
would be like expecting a poodle to outcompete a wolf, or a housecat to
steal territory from a lynx.
 
A third and very important factor is that to maintain a feral colony the
population levels of the animal must be large enough to overcome inbreeding,
predation, disease, and accident.  They also must be reproductively viable.
In the USA, ferrets are not released nor lost in sufficent quantities for
the former.  Escapes or releases are small compared to the population, and,
judging from published animal control figures, are too infrequent to become
a problem in any one area.  As for the later, the vast majority of ferrets
have been neutered, which makes sustaining populations impossible.  Think
about this.  Suppose in a breeding poulation of feral ferrets, the number of
breeding pairs is 100.  They live an average of 4 years.  To maintain
population levels, at least 200 ferrets must enter the population every four
years.  Cut their gonads out, and now 50 new ferrets have to be lost or
discarded each year in that specific area in order to maintain populations.
Now that is surviving animals.  In the wild, 90-95% of all newborns never
reproduce.  If the same numbers were true for lost pets, you would need to
lose 1000 animals to have 50 survivors.  In one specific area.  Not very
probable.
 
Fourth, the area a feral animal moves into must be large enough and well
populated with prey species enough to support the feral population.  Because
ferrets take after polecats in the respect that they are solitary
territorialists, the area required to support a self-sustaining population
is quite large.  The more marginal the environment, the larger the area.
Imported animals almost always take over areas that have been impacted or
disrupted by outside forces.  Since this type of disruption also impacts the
local prey species, the introduction of the domesticated ferret suffers from
bad timing.  It could happen, but not likely unless the disruption was like
in New Zealand, where the introduction of the rabbit, mouse and rat were the
disruptive agents.
 
A fifth requirement for feral animals to be sucessful is the continued
recruitment of additional animals, and the association of those feral
animals with humans.  Studies have shown feral dog and cat groups actually
would die out if left entirely on their own.  The feral ferret in Britain
also seen to follow this pattern.  Thier reproductive rate cannot keep up
with the deaths from malnutrition, disease, and accidents.  With feral
populations, the numbers are always increased by the sheer numbers of
additional animals brought in on a continuous basis.  For ferrets to become
feral, the same rule must apply, but since their numbers compared to the dog
and cat populations are small, and they are not lost or discarded in such a
frequency as to make colonization possible, the ability to maintain a
self-sufficent population is statistically improbable.
 
Sixth on the list is feral ferret must be able to recognize and capture
food.  Comparisons to feral cats and dogs is not only improper, but
misleading because the hunting techniques and learning methods are so
different.  Both dogs and cats are visual hunters.  Dogs can learn to kill
on their own, but cats seem to need to be taught the killing bite.  Ferrets
are olfactory hunters, and imprint on prey smells at a very young age.
Ferrets also need to learn hunting techniques, even more so than the cat.
In other words, cats and dogs look for prey and ferrets sniff for prey.
This in not to say the opposite is not true; just far less important.
Because of this, ferrets that have not imprinted on prey smells have almost
no chance of becomeing feral because they do not recognize living animals as
food.  In the USA, few ferrets are fed anything other than kibbled foods,
making introduction into the wild a virtual impossibility.
 
Next post: more on requirements of ferality.
 
Mo'Bob and the 18 Kibble Kritters (Missing Gus)
[Posted in FML issue 1760]