Feral cats, TNR, & what we could learn from the fall of Rome

Video “Covid-19 & TNR for cats”

https://www.youtube.com/watch?v=v_AWoreQQ_I&feature=youtu.be&fbclid=IwAR3wEMorrwskWhz6am72-SEkUQYzEeFXynGOO9kQyNZ0_HbSS1alKlTfAd0

Reviewed by Merritt & Beth Clifton

Edward Gibbon,  in authoring the 1776 six-volume tome The History of the Decline & Fall of the Roman Empire,  said nothing of feral cats,  but a parallel plot outline may be developing––just out of sight and out of mind––in and around the downtown alleys and low-income residential neighborhoods of the United States:  the areas most under-served by neuter/return programs and most likely to suffer from the shutdown of low-cost and free spay/neuter clinics occasioned by COVID-19.

To succinctly refresh memories,  the Roman Empire conquered,  absorbed,  and for about 500 years governed most of Europe,  the Middle East,  and parts of North Africa through a sustained strategy of in effect neutering the “barbarian” [meaning bearded] armies of neighboring territories,  sometimes literally trapping foes and cutting their balls off.

The Romans then brought the “barbarians” into the empire as rapidly as they could be tamed and introduced to Roman ways,  including frequent shaving.

Plagues & chaos interrupted Roman system

The Roman system worked much more effectively and enduringly than the capture-and-kill approach to conquest of most previous empire-builders,  even during the cultural transition from paganism to an evangelical brand of Catholicism,  which was not warmly welcomed by many Roman subjects.

(See Drove out the snakes? What did St. Patrick do with the Irish wolves?)

            But the Roman approach depended entirely upon sustained expansion,  so that the “barbarians” were always pushed back,  never allowed the opportunity to build military strength,  form alliances,  and overrun the outermost Roman enclaves.

Late in Roman history,  chaos––including plagues––within Rome itself diminished the ability of the Romans to push back the “barbarians.”

Encroachment from the Germanic tribes of the north and west,  and Mongol tribes in the east,  eventually led to the Visigoth sacking of the city of Rome itself on August 24,  410 CE.  The invasion of Rome was led by the renegade former Roman general Alaric,  ancestrally a Visigoth,  who was loyal to Rome until the Roman government was disloyal to him and his army.

No scholars of strategy behind Covid 19 & TNR for cats

ANIMALS 24-7 and everyone else favoring fewer feral cats at large hopes there will be no need to write The History of the Decline & Fall of Neuter/Return,  due to suspensions of spay/neuter services during the 2020 COVID-19 pandemic crisis.

Meanwhile,  though,  it is evident that no scholars of strategic history––military,  classical,  or otherwise––had substantive input into the newly released feel-good Alliance for Contraception in Cats & Dogs video Covid-19 & TNR for cats.

Successful neuter/return,  or TNR,  works essentially through application of the Roman strategy,  continually extending TNR projects into the neighborhoods and other feral cat colony areas that have not yet been reached.  This is essential to prevent fertile cats from those areas from meandering in to repopulate the areas in which 75%-plus of the resident cats have been sterilized,  re-occupying whatever carrying capacity is left vacant when the resident cats fail to reproduce and die out.

What Covid 19 & TNR for cats gets right––and wrong

            Covid-19 & TNR for cats starts with a reasonably accurate explanation of “carrying capacity.”

Covid-19 & TNR for cats acknowledges the importance of sterilizing 75% of a cat population to achieve a gradual population reduction.

Covid-19 & TNR for cats acknowledges also the importance of frequently revisiting areas served by neuter/return to ensure that abandoned cats and immigrant cats migrating into the habitat do not push the percentage of unsterilized females,  in particular,  below 70%,  the level at which the population will remain relatively stable.

What Covid-19 & TNR for cats does not acknowledge,  or even seem to realize,  is that many and perhaps most of the habitats where 75%-plus of the cats at large have already been sterilized are surrounded by habitats in which few if any cats have been sterilized yet.

How rapidly can the “barbarian” cats invade?

The habitats where 75%-plus of the cats at large are already fixed appear to include most of the places where upward of 70% of the total U.S. feral cat population lived circa 1990.

These are,  specifically, the places with the most people who are actively feeding cats,  and/or with the most accessible other food sources,  such as restaurant and supermarket dumpsters and fishing piers.

Thirty years of intensive neuter/return activity in high-density cat habitats has gradually produced a net decline of 70%-plus in the total U.S. feral cat population of today––but that happens to be beside the point.

Cat population vs. competitor species

The issue at present is not how many feral cats persist at large overall,  but rather how rapidly the unchecked reproductive capacity of the fertile cats remaining can refill vacant carrying capacity––and what happens next.

The trickle of unaltered cats coming into territory already covered by effective TNR programs can be effectively addressed,  just as Covid-19 & TNR for cats describes,  if and only if the cat population migrating in from surrounding areas is suppressed enough to enable rodent-eating wildlife such as hawks,  owls,  eagles,  foxes,  fishers,  and coyotes to find and occupy the carrying capacity that resident feral cats have lost.

Meanwhile,  critical to consider is not just the reproductive capacity of the fertile cat population in the many unserved and under-served habitats surrounding habitats where TNR has been effective.

Covid-19 & TNR for cats gets population structure backward

Also to be considered is the reproductive capacity of the fertile cats remaining in the habitats where TNR has long been practiced.  These cats may be compared to the huge population of “barbarians” who had been relatively peaceably absorbed by the Roman empire,  whose allegiance to Rome failed when Rome was no longer paying and protecting them.  At that point many of those “barbarians” joined Alaric’s army.

Here is where the Covid-19 & TNR for cats modeling goes farthest astray.

The Covid-19 & TNR for cats scenario postulates that only 50 cats are in the habitat already reached by TNR,  while 200 non-sterilized cats remain in the surrounding neighborhood.

Covid-19 & TNR for cats takes in to consideration immigration from that surrounding area,  plus some abandonment of household cats,  but gets the typical population structure upside down and backward.

How cats missed by TNR become a “fifth column”

A typical TNR treatment area is,  as explained above,  a place where cats were already congregating around an easily accessible and attractive food source,  for example a trailer park inhabited by several active feeders, with only 50 cats in the surrounding “food desert,”  where the cats have to hunt mice for a living among sprawling parking lots,  busy streets,  and relatively inaccessible workplaces whose occupants do not discard much edible refuse to attract mice.

If one assumes 75% sterilization within a TNR area including 200 total cats,  there will be 150 sterilized cats & 50 fertile cats already present,  along with the 50 fertile cats in surrounding areas.

Maintaining 75% sterilization

This means the reproductive capacity of both populations is approximately equal.  Assuming that 100 of the cats in the TNR area are female,  including 25 fertile females whom the TNR program has not reached,  they would produce about 100 kittens each spring,  about 50 of them female.

About 25 of those female kittens would survive to birth about 100 more kittens in the fall, with about 25 female survivors from those litters joining the population of fertile females in spring, including the survivors among the original 25 fertile females and the 25 first-time mothers.

Assuming 50% attrition among the older cats, you would again have 50 fertile female cats next spring.

According to the Covid-19 & TNR for cats model,  75% sterilization is maintained by annually sterilizing X-number of fertile females.  The algebra suggests that this number is equal to the number of fertile females immigrating in from the surrounding territory plus the number abandoned by humans.

That number would plausibly appear to be 35-40 cats.

Attrition

Also to be considered is attrition among the already sterilized cats,  which will be steadily opening up habitat.  Since sterilized cats live longer,  suppose the attrition rate is only 10%, instead of the 50% found among the unsterilized cats.  This means there are about 15 extra habitat niches per year within the TNR area, over and above those occupied by kitten births.

Normally those niches are filled by immigrant cats who are caught and sterilized,  with the balance of the caught-and-sterilized immigrant cats apparently being removed for socialization & adoption.

(The Covid-19 & TNR for cats model,  as explained in the video,  does not mention either the effects of attrition or removal for socialization and adoption,  also a form of attrition,  in that it also opens habitat to other cats.)

Now TNR is suspended for just one spring.  Instead of having 50 fertile fertile female cats at the outset, the habitat will have 85 to 90,  counting fertile immigrant cats and abandoned cats who are not sterilized.

The “barbarians” march

Instead of having 25 fertile female offspring to add their litters to the population born in the fall,  there will be around 45, for a fall birthing population of about 95,  nearly twice what it was,  even before taking additional immigrant cats and abandoned cats into account––and with spay/neuter services in general disrupted,  not just those serving TNR programs,  the number of abandoned cats will accelerate.

There are still only 15 extra habitat niches opening up through attrition among the previously sterilized cats,  though,  so now the survivors among the extra births will begin to move out into the surrounding territory.  Now the TNR area will actually become a source of additional cats in nearby neighborhoods. This added population pressure will motivate more of the cats in the unserved and underserved habitat to move outward.

In short,  the Visigoths are on the march,  and Rome is imperiled.

Restoring the previous order would require ramping up population maintenance sterilization capacity from 35-40 cats per spring/summer to double or triple that many before the next spring –– if the cats can be caught, and once they fan out from the initial TNR area,  that gets to be more and more difficult.

TNR programs do not control most feral cat habitat

When sterilization services are stopped,  even through one kitten season,  it is both the cat population within the habitat already well-served by neuter/return and the cat population outside that grows.

With the population reduction pressure on the “barbarian” feral cats beyond the imperial gates removed,  those cats can more rapidly expand into empty carrying capacity in any direction,  and––since cats breed much more prolifically than most rodent-eating wildlife––out-compete wildlife to fill it.

Simultaneously,  the unsterilized “barbarian” feral cats within the TNR territory are not only refilling any vacated carrying capacity where they are,  but also joining the “barbarian” cats outside the gates in their invasion of new habitat (or,  mostly,  habitat left accessible by the success of past TNR campaigns.)

The modeling done in Covid-19 & TNR for cats begins from the presumption that imperial Rome,  or neuter/return programs,  controls a much greater share of the available habitat than the feral “barbarian” hordes,  to a much greater extent than evidence really supports.

Therefore,  Covid-19 & TNR for cats asserts,  the imperial Roman legions,  or TNR practitioners,  can beat the bearded foes back,  even if they delay marching out to do it for an entire year due to the suspensions of spay/neuter services prescribed by the American SPCA,  National Animal Control Association,  et al due to the COVID-19 pandemic.

Follow the money

Incidentally,  the original modeling behind Covid-19 & TNR for cats was funded in 2015 by the ASPCA,  one of the organizations most culpable for failing to defend the operation of spay/neuter clinics as an essential service.

The Covid-19 & TNR for cats modeling starts from a variety of points which presume that from 50% to 75% of the female cats in a given habitat are sterilized,  which is reasonable enough in parts of the U.S.,  but wishful thinking at best in most of the rest.

If the female cat sterilization rate in an area already served by TNR is as low as 50%,  the disaster detailed above will be half again worse.

Don’t underestimate the foe

Modeling that underestimates the capacity of the “barbarian” hordes to regroup,  reoccupy neglected territory,   and invade vulnerable habitat ever more aggressively is exactly the sort of thinking that eventually enabled Alaric the Visigoth to overrun Rome on his third attempt,  around 550 years after Hannibal the Carthaginian failed,  even with the help of elephants.

Alliance for Contraception in Cats & Dogs president Joyce Briggs appropriately concludes her 13-minute narration with a warning that computer modeling does not always accurately predict what happens in real life.

Covid-19 & TNR for cats falls short,  however,  not from a defect in the modeling technique itself,  but rather from a defect in the input data,  recalling the computer programming adage “garbage in,  garbage out.”

Fiddling while Rome burns

Commented Alliance for Contraception in Cats & Dogs board member G. Robert Weedon, DVM,  on his personal Facebook page,  “The model results were both encouraging and thought-provoking —showing that in colonies where TNVR [trap-neuter-vaccinate-release] had been performed, there would not be an explosion of kittens (as was dreaded by some),  and the effort to make up lost ground after sterilizations resume will be achievable.”

Indeed,  what was left of Rome post-Alaric regrouped and,  as a much reduced empire,  survived for another thousand years,  until the fall of Constantinople in 1459.  But the “barbarians” prevailed everywhere else.

Neuter/return will survive as a feral cat population management technique.

This scarcely means that many years,  and in some locales,  several decades of diligent progress achieved through neuter/return will not be lost.

Fortunately some spay/neuter surgeons,  including Weedon, have ignored the ASPCA advice,  and found safe ways to keep operating.  If the feline Visigoths are stopped at the Rhine,  the Rhone,  the Rubicon or the Tiber,  it will be because of their efforts,  not because the potential cat-astrophe was not all that serious.

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