Where cats belong–and where they don’t
From ANIMAL PEOPLE, June 2003:
KISSEEMEE, Florida–Depending on who you listen to, the
Florida Fish & Wildlife Conservation Commission either declared war
on feral cats at a May 30 meeting in Kisseemee, or clarified their
position that they have no intention of so doing.
Claiming the support of the American Bird Conservancy,
National Audubon Society, and National Wildlife Federation, Florida
Wildlife Division director Frank Montalbano talked like a man going
to war in a March interview with Orlando Sentinel outdoors writer Don
“We estimate there are 5.3 million feral and free-ranging
domestic cats in the state,” Montalbano said. “We’re going to take
an aggressive policy toward eliminating the feral cat impact on lands
this agency manages. Cats roaming free in wildlife management areas
will be taken into captive management or euthanized. We may have to
get involved in euthanasia,” Montalbano reiterated, “in situations
where [nonprofit] corporations are maintaining colonies of feral cats
near populations of native endangered species.”
Montalbano, said Wilson, “was referring to a group of cats kept by
condominium owners on Key Largo, home of the Key Largo wood rat.”
Montalbano’s remarks touched off a furor, especially in
south Florida, where trap/neuter/return of feral cats, called TNR
for short, has taken hold in a big way.
Data developed separately by the FFWCC and by University of
Florida at Gainesville researcher Julie Levy agrees that Florida now
has 2.7 million to 2.8 million feral cats, amounting to 44% of the
total cat population–about twice as many cats per 1,000 human
residents and twice as high a percentage of ferals as the current
U.S. norms. The Florida climate enables cats to go through two and
even three successful breeding cycles per year, against the norm of
one in the snowbelt states.
Yet Florida used to have even more feral cats.
Since local TNR programs began in south Florida during the early
1990s, animal control killing per 1,000 human residents has dropped
by half, and reductions in the numbers of cats killed are believed
to account for most of the improvement.
In 2001, for instance, all shelters combined in the Fort
Lauderdale/Miami corridor killed 14.1 cats and dogs per 1,000
humans, less than the national average of 15.7, and down from 33.0
per 1,000 as recently as 1997.
In Tampa, where TNR has not taken hold, shelters
collectively killed 32.4 cats and dogs per 1,000 humans in 2001. St.
Petersburg, right across Tampa Bay, with several active TNR groups,
Florida Fish and Wildlife Conserv-ation Commission field
biologist Dwayne Carbonneau and northeast regional director Dennis
David followed Montalbano in spooking cat people when in mid-May they
accidentally left a conversation between them on the answering
machine of Alley Cat Allies in Washington D.C.
Neither realized that David’s telephone was still connected
to the answering machine, after David left a brief message about the
May 30 FFWCC meeting.
“Should I wear my uniform when I’m shooting these
neighborhood cats?” asked Carbonneau.
“Only after we adopt this policy,” David said.
Softening their initial tone as cat defenders bared their
claws, but perhaps using doublespeak, the FFWCC unanimously voted
“To pursue staff recommendations and all of the strategies outlined
and to oppose TNR only when it is a threat to native wildlife and
then in the most socially acceptable way we can.”
The approved strategies include:
* “A comprehensive education program to increase public
awareness of the impacts that feral and free-ranging cats present to
wildlife,” which feral cat advocates read as mounting an anti-cat
* Identifying “ways for cat owners to minimize impacts,”
meaning keeping cats indoors.
* Informing “cat owners of laws prohibiting the release or
abandonment of cats to the wild,” read by many TNR practitioners as
an attempt to legally define them as owners and arrest them. This
tactic has failed when attempted in other states.
* Eliminating “the threat cats pose to the viability of
local populations of wildlife, particularly species listed as
endangered, threatened or of special concern,” perhaps hinting at
an escalation of catch-and-kill.
* Prohibiting “the release, feeding or protection of cats
on lands managed by the Florida Wildlife Commission and strongly
opposing programs and policies that allow the release, feeding or
protection of cats on public lands that support wildlife habitat.”
This much was already public policy and is also the policy of the
National Park Service, U.S. Fish & Wildlife Service, U.S. Navy,
U.S. Postal Service, and other federal agencies.
* Providing “technical advice, policy support and
partnerships to land management agencies in order to prevent the
release, feeding or protection of cats on public lands that support
wildlife habitat,” read by TNR practitioners as a mandate for
creating an interagency cat extermination force.
* Opposing creation and supporting “elimination of TNR
colonies and similar managed cat colonies wherever they potentially
and significantly impact local wildlife populations,” which some TNR
practitioners read as meaning anywhere, although the phrase
“potentially and significantly” leaves room for tolerating low-level
predation on rodents and common bird species in developed areas,
where other predators such as coyotes and gulls are either few or
* Evaluating “the need for new rules to minimize the impacts
of cats on native wildlife.”
The FFWCC tried to mollify cat defenders by stating that it
“is not making drastic plans to kill cats; rather it is looking to
employ the least-restrictive methods possible to accomplish the
agency’s mission to protect wildlife.
The FFWCC also indicated that it would not take the active
role that some cat advocates fear in conducting feral cat roundups:
“Commissioners agreed that local governments have the primary
responsibility for managing domestic animals, including cats, and
the FFWCC will concentrate its efforts on coordinating with them and
other affected parties.”
In other words, catch-and-kill on land not under direct FWC
management is still delegated to local animal control agencies,
whose policies and activities are still under the direction of local
Elaborated FFWCC spokesperson Joy Hill to Associated Press
writer Mike Schneider, “We’re not forming a cat Nazi-patrol. That’s
not what this is about. It’s about protecting wildlife.”
Skeptical, Alley Cat Allies challenged the new FFWCC policy with a
June 10 lawsuit.
How great a difference the new FFWCC policy will actually
make remains to be seen. Although it lends itself to extremes of
interpretation, it really does little more than restate the
longstanding perspectives and policies of wildlife agencies all over
It also marks the first major state level escalation of a
policy debate already underway in communities with both active TNR
programs and active birders who blame cats for declines of
ground-nesting birds and songbirds. Friction over the alleged impact
of feral cats on a small reintroduced population of California golden
quail in Golden Gate Park has raged for more than a decade.
A similar confrontation in Akron, Ohio, brought the
extermination of 969 cats trapped by cat-unfriendly residents during
the latter half of 2002.
While the Florida debate was underway, comparable
resolutions were under discussion in Oakland, Michigan, and
Few cities and counties and even fewer states have existing
written feral cat policies because historically feral cats were not
recognized as a presence, much less a problem. Feral cats were not
covered in the model animal control ordinances circulated by national
animal advocacy groups as recently as the early 1990s; there is no
corpus of common law pertaining to them; and felis catus, their
species, is not even mentioned in the Bible, even though cats were
and are native to the Middle East.
Recognition of the existence of feral cats in great numbers
may be traced to the 1982 first publication of Maverick Cats, by
Ellen Perry Berkeley.
Feral cats at the time were still generally seen–if seen at
all–as a rural phenomena, haunting dairy barns where they hunted
mice in haylofts and begged for milk.
Urban feral cats were presumed to be strays, and urban cats
dumped in rural habitat were believed to have a very low survival
rate. At Tilden Park in the hills above Berkeley, California, for
example, the ranger lecture given to visiting schoolchildren during
the 1960s and early 1970s included inspecting cat bones and hearing
about how cruel it was to dump unwanted cats to “give them a chance”
because a typical urban cat could not catch enough mice and birds to
Discussion of the possible impact of feral cats on rare
resident birds and reptiles was added after the passage of the
federal Endangered Species Act in 1973.
The Walt Disney film Lady & The Tramp (1955) marked the
apparent turning point in a battle begun with the passage of the
first U.S. animal control ordinances to persuade Americans to confine
dogs at home and have them wear identity collars. The popularity of
the film apparently accomplished what more than 200 years of
municipal dog-catching and 100 years of humane society lecturing had
not. Within the next 25 years allowing dogs to run at large passed
from being the American norm to being a socially unacceptable act in
most parts of the country, but not even Ellen Perry Berkeley seems
to have given thought to what the disappearance of free-roaming dogs
might mean to feral cats.
What happened was that confining dogs opened habitat and
diurnal hunting and travel opportunities to a self-sustaining cat
population who until then had been confined to places where dogs
could not go, hunting and traveling mostly by night.
Coyotes, foxes, raccoons, deer, and opossums also took
advantage of the absence of dogs to claim urban territory, but cats
had the dual advantages of already being there, albeit mostly
unseen, and of having by far the greatest fecundity, enabling them
to rapidly breed up to approximately the same biomass as the dogs
whose jobs as refuse raiders and rodent-catchers they took over.
Between 1960 and 1985, available records indicate, the
numbers of “stray” cats killed by U.S. animal control agencies
approximately tripled, even as dog intake leveled off and began to
In gist, each free-roaming dog weighing 30 pounds on average
was replaced by three 10-pound cats.
Feral cats became the most abundant and reproductively
prolific mammalian predator/scavenger in the urban environment.
That in turn brought feral cats to the attention of animal
advocates and wildlife researchers.
“Fewer than a dozen research papers [about feral cats] had
been published by the mid-1970s,” recalls Ellen Perry Berkeley in a
the new final chapter of a 2001 reissue of Maverick Cats. “We now
have more than 20 times that number.”
Most of the new studies focus on the relatively obvious
predatory role of outdoor cats, but a few researchers have also
recognized the importance of cats as prey.
Coyotes and foxes often take urban habitat niches from feral
cats by force. A 1998 study by the late Martha Grinder (killed in a
1999 car accident) and Paul Krausman, of the University of Arizona
in Tucson, found that feral cats were among the main prey of urban
coyotes. A1999 study by Kevin Crooks and Lee McClenaghan, of San
Diego State University, affirmed the Grinder/Krausman work by
discovering cat remains in 21% of the coyote scats they found in
canyons near San Diego.
As hawks, owls, and eagles recovered from the reproductive
depression of the 1950s through the 1970s caused by exposure to the
pesticide DDT, many species–including bald eagles–surprised
ornithologists by thriving as readily in some cities as out in the
wild. Cats, it seems, have also become a big part of urban
raptors’ prey base.
The common view of cats as a top predator in the wildlife
food pyramid because they are wholly carnivorous is true of most wild
species, but not of felis catus, who shares with coyotes the
distinction of being among the few predators with the fecundity of a
During the peak years of the U.S. government Animal Damage
Control coyote-killing campaigns of the 1950s through the 1970s,
biologists found that the average coyote litter size in Texas grew
from four pups to seven. This occurred because the intense ADC
hunting pressure on coyotes shifted the odds of pup survival from
favoring the pups who got the most maternal care to favoring the
offspring of the coyote mothers who could produce the greatest
abundance of pups, among whom some might elude the killers.
In addition, with food competition artificially reduced,
the coyotes wiley enough to survive were able to feed more pups.
The ancestors of felis catus were chiefly the African desert cat,
with some apparent genetic input from the Pallas cat of Asia Minor
and the closely related Scots wildcat and Norwegian skaucat. All are
still capable of hybridizing with felis catus, but all normally bear
just two kittens. That was also true of the felis catus specimens
who were mummified by the ancient Egyptians circa 4,000 years ago,
and was probably still true of felis catus as recently as the 14th
Between 1334 and 1354, however, bubonic plague killed up to
75% of the human population of Europe and Asia. Brought to Europe by
flea-infested black rats who stowed away aboard the vessels of
Crusaders returning from the Middle East, the so-called Black Death
attacked most virulently after terrified cities blamed it on
“witchcraft” and purged from their midst both the majority of people
who had medicinal skill (mostly older women) and their “familiars,”
mostly the cats who pro vided rat control.
Cat-eating was first reported in Guangzhau, China, in 1346,
putting the Asian population of felis catus under similar pressure,
continuing in much of China, Korea, and some other Asian nations to
Human predation on cats waned in Europe for several centuries
after the Black Death, but resurged during a British purge of
“witches” in 1665, just before The Great Plague of London.
Intensive human predation on felis catus in the Americas
peaked with the height of catch-and-kill animal control in the U.S.
during the 1970s–much of it done, then and now, by humane workers
who believe they are “euthanizing” helpless abandoned cats to save
them from suffering.
Regardless of motive, the effect on the feral cat population
replicates natural predation: the most frequent victims are the very
young, the old, the disabled, and the ill. The healthiest animals
usually escape to breed up to the carrying capacity of the habitat,
if they can.
Responding to the intensified mortality, felis catus now
bears an average litter of four. Nearly seven centuries of killing
cats doubled the fecundity of the species.
Why TNR works
TNR is biologically effective in reducing cat numbers while
predation is not because it inhibits the reproductive potential of
the survivors. When at least 70% of the potential breeders in any
species from viruses to advanced mammals are vaccinated, or
sterilized, which amounts to vaccination against pregnancy, the
remainder have difficulty reproducing at more than the replacement
level. This is because the potentially reproductive population is
not only diminished, but also isolated from each other, among
specimens of the same species who hold habitat and whose sterility is
Each vaccination or sterilization above 70% further reduces
the reproductive potential of the target species. The species can
even be eradicated, as smallpox was during the 1970s (at least
outside of laboratories), if there is not a favorable vacant habitat
into which the fecund few can expand and resume high-volume
If feral cats were to be eliminated from the U.S., hawks,
owls, eagles, foxes, and coyotes would eventually capture their
prey base–but feral cats reproduce at from two to six times the rate
of any of these rival predators. Until the rival predators are
numerous enough to eat any feral cats who try to reclaim a vacant
habitat niche, the animals most likely to fill open niches are more
Critical to understand is that this is not a matter of cats
exercising territoriality. Few predators are more gregarious with
each other than felis catus. Even dominant toms who drive away rival
toms during mating season may befriend them outside of mating season.
Feral cats hold habitat niches by consuming the available food supply
and occupying the safe cover. They surrender habitat niches to other
predators through attrition, as the other predators become able to
take the niches away from them.
How many cats?
“Of the 73 million pet cats in the United States,” Heidi
Ridgley declared in the April 2003 edition of the National Wildlife
Federation membership magazine National Wildlife, “an estimated 40
million roam outside unsupervised. Throw in feral cats-the
unsocialized offspring of discarded or lost pets-and as many as 100
million cats are on the loose. ‘These cats could easily be killing
100 million songbirds a year,’ says Al Manville, wildlife biologist
at the U.S. Fish and Wildlife Service Migratory Bird Management
Ridgely succinctly presented the worst fears of birders and
conservationists about feral cats, but much of her information was
either outdated or contextually misplaced.
ANIMAL PEOPLE estimated in 1992 that there were about 26
million feral cats in the U.S. at the low end of the annual
population cycle in the depth of winter, and about 40 million at the
summer peak of kitten season.
These estimates were projected from information about the
typical numbers of cats found in common habitat types, gleaned from
a national survey of cat rescuers sponsored by Carter Luke of the
Massachusetts SPCA, and were cross-compared with animal shelter
TNR was then just beginning to be practiced in the U.S., and
was not even called TNR yet.
After a decade of intensive TNR in much of the country, 40 million
is now very close to being the upper-end plausible estimate of all
free-roaming cats in the U.S., including both pets and ferals, and
then only at the height of “kitten season,” when about half of the
total feral cat population are still too young to hunt, with
approximately a 50% chance of living long enough to ever hunt
In 1996, based on a follow-up survey of the same cat
rescuers who were polled in 1992, ANIMAL PEOPLE estimated that the
feral cat population had probably peaked in 1993 or 1994 before
beginning a downward trend.
ANIMAL PEOPLE projected the annual rate of decrease in the
feral cat population since peak at a maximum of 11% per year, if TNR
was performed with uniform vigor throughout the U.S.
ANIMAL PEOPLE also projected the maximum rate of assimilation
of feral cats into homes, over and above the historical rate of
about 25% found by many other researchers, as also being 11%.
Since 1994 the actual rates of decrease in the feral cat
population and of assimilation of feral cats as pets appear to have
been about half the maximum, because the maximum potential for using
TNR effectively has only been half realized. Thus the winter feral
cat population may now be as low as 13 million and the summer peak is
probably no more than 24 million.
There is indirect confirmation of these numbers from other sources.
The American Animal Hospital Association estimated in 1997, based on
veterinary client surveys, that there were about 59 million pet cats
in the U.S. One year later the American Pet Product Manufacturers
Association estimated that there were 63 million pet cats.
The parallel surveys have shown similar increases in the pet
cat population ever since. Currently the AAHA projects that there
are 78 million pet cats in the U.S., for a 32% rise in six years.
Yet even a decade ago separate studies by the Tufts
University Center for Animals & Public Policy, the Massachusetts
SPCA, and Karen Johnson of the National Pet Alliance found that the
owned cat population, including cats deliberately bred by the pet
industry, appeared to be reproducing at only 70% of their own
Even then, up to 85% of all pet cats had already been
sterilized, amounting to 60% of the estimated total U.S. cat
population of about 100 million.
The pet cat population was maintaining itself and growing
only through taming and adoption of ferals. Surveying 20,000
California households in the San Diego and San Jose areas during
1993-1994, Johnson learned that at least 28% of the cats kept as
pets were apparently born feral–a slight rise from the findings of
the Tufts and MSPCA studies, which were done in 1991, but
consistent with the trend reported by other researchers since 1981.
Johnson also learned that about 10% of all the surveyed
households fed feral cats, who also amounted to about 10% of the
total cat population, and that about 9% of the feral cats had been
Overall, 64% of the San Diego and San Jose cats could no
longer reproduce, bringing the total cat population close to the 70%
threshold for zero growth.
No comparable surveys have been done in the rest of the U.S.
yet, but as of 1996, according to American Veterinary Medical
Association data, the number of pet cats in the U.S. acquired from
all sources and the number of cat sterilization surgeries performed
balanced, at 8.4 million of each.
At that point the pet cat population could no longer
reproduce at even replacement level. Up to a third of all pet cats
now appear to be recruited from the feral population–and the volume
of sterilizations performed each year may exceed recruitment.
The bottom line is that while the pet cat population has
grown by 32%, the total cat population, ferals included, is still
no more than the 100 million who inhabited the U.S. in 1992, and is
very likely less.
How many birds?
The estimate of feline predation on birds at about 100
million per year that Al Manville gave to National Wildlife, at
approximately one per cat, is probably low. It is certainly a much
more conservative projection than most.
In early 2000, in perhaps the most thorough study of cat
predation on birds to date, albeit analytically flawed, Carol Fiore
of the Wichita State University Department of Biological Sciences put
the annual pet cat toll on birds in the U.S. at anywhere from 134
million, if half of all pet cats roam (about 34 million), to 269
million, if every pet cat roams.
Fiore did not try to estimate the numbers of birds killed by
feral cats, but even her lower estimate markedly overprojected the
number of owned cats who are allowed to roam. This happened because
Fiore decided, based on a survey of Wichita residents, that about
half of all cat-keepers allow their cats to roam, and presumed that
could be extrapolated to mean that half of all pet cats roam.
ANIMAL PEOPLE has much more extensive data about cat-keeping
norms on file, from various other studies, which indicates that
cat-keepers whose cats do not roam have, on average, from two to
three times more cats than those whose cats can roam.
In other words, more than two-thirds and perhaps 75% of all
pet cats do not roam. The roaming pet cat population would therefore
be no larger than 26 million.
There is a fairly obvious reason for the greater abundance of
non-roaming cats, in that cats kept from running at large tend to
live much longer, avoiding cars, wild predators, and capture by
animal control officers.
Ferals kill fewer
Accordingly, even Fiore’s lowest estimate of pet cat
predation on birds may be twice too high. If Fiore was correct that
free-roaming pet cats kill an average of 4.2 birds per year, the
toll by pet cats would be 109 mil ion.
The feral cat toll on birds is unlikely to be more than half
as high as the pet cat toll.
First, there may be twice as many free-roaming pet cats as
ferals old enough to hunt for a living.
Second, ferals who hunt for a living tend to hunt mice by
night, not birds, who are mostly not out at night.
Third, feral cats appear to hunt no more, and perhaps less,
than free-roaming pet cats. This is because, like other wild
predators, they hunt not for sport but for food, and hunting more
prey than they can eat is a pointless waste of energy. Conservation
of energy is a critical concern of predators, who typically sleep
about twice as much as primarily plant-eating prey species (except
when prey species hibernate).
Only the well-fed cat can afford the energy expenditure
involved in hunting just for fun– especially when the prey is not to
be eaten, like the lizards, shrews, and chipmunks commonly killed
and abandoned by pet cats.
Finally, relatively few cats are even capable of
successfully hunting birds.
Perhaps the best-known study of predation by individually
monitored cats was published by the British-based Mammal Society in
February 1998, based on their Mammal Action Cat Survey. Eight
hundred British cat-keepers recorded their cats’ kills for six
months: 144,000 cat-days of activity.
The most active feline killer was Missy, with 125 kills in 180 days,
including 28 birds. Almost all the rest were mice, voles, and
other small rodents.
The runner-up was Kipper, with 82 kills in 180 days,
including six birds. The two most predatory cats (by far) among the
entire sample base killed only 34 birds between them in 360 cat-days
of hunting. They managed to kill birds at a rate amounting to 16% of
their total prey, and succeeded in killing a bird on only 9.4% of
the days they hunted.
Only about one cat in 10 has the vertical visual acuity to
catch a bird who takes flight–a hypothesis easily tested with a wad
of paper on a string. Most cats will easily lcatch the paper when it
moves horizontally, like a mouse, but nine of 10 will lose track of
it if it is jerked up into the air like a startled bird.
Cats, in short, are rarely the primary cause of the death
of the birds they catch. Bird-hunting cats obey the same rules of
predation as all other animals who hunt for a living, dispatching
primarily the sick, the injured, the elderly, and the very young,
especially fledglings who try to fly too soon. Cats also finish
birds who become drunk from eating fermented berries, poisoned by
pesticide ingestion (typically with recently sprayed insects), or
who collide with human-created obstacles.
The ecological role of cats in preventing the spread of bird
disease by killing and eating those brought to the ground by
infection has barely been studied, but it may be that feline
predation is overall more beneficial to birds than harmful.
Examining the spleens of 500 birds who were either caught by
cats, flew into windows, or were hit by cars, researchers Anders
Moller and Johannes Erritzoe of the Universite Pierre et Marie Curie
in Paris reported in June 2000 that the spleens in the cat-killed
birds were a third smaller on average, in 16 of 18 species, than in
the birds killed in accidents. In part this was because 70% of the
cat-killed birds were juveniles; only half of the others were. But
a more important factor, Moller and Erritzoe suggested, was that
“Birds succumbing to lots of infections, or inundated with
energy-sapping parasites, have smaller spleens than healthy birds.”
Who killed Cock Robin?
All considered, the Fiore data suggests that contrary to her
own conclusions, pet and feral cats combined probably kill no more
than 163 million birds per year in the U.S.
By comparison, human hunters shoot at least 74.4 million
wild birds per year, including about 35 million mourning doves.
University of Pennsylvania researcher Daniel Klem estimates that
about 100 million birds per year die in collisions with window glass,
exclusive of birds who hit the glass first and then are caught by
cats. Another four million birds per year die in collisions with
cellular telephone transmission towers, also exclusive of birds
scavenged by cats.
The Dr. Splatt and Strah Poll roadkill counts indicate that
about 11 million to 18 million birds whose remains are big enough to
be seen from a car and/or cause a road hazard are roadkilled by cars
National Wildlife Federation vice chair and Virginia Wildlife
Center director Edward Clark recalls that, “A study done by the U.S.
Fish & wildlife Service of pesticide mortality shows that even with a
grid search of a field in which dead birds had been planted 24 hours
earlier, the discovery was only about 5%, which means that 95% were
either removed by scavengers or went unnoticed.”
If the same ratio applies to roadkilled birds, the vehicular
toll would be 220 million per year.
Clark, an outspoken critic of TNR, told Heidi Ridgley of
National Wildlife that the Virginia Wildlife Center treats about 600
cat-injured animals per year, of whom under 20% recover.
“We have no way of knowing if cats are to blame for the
orphaned animals we get,” Clark added.
Wrote Heidi Ridgley, citing Clark, “The ‘fortunate’ few
whom people pry out of their cat’s claws and turn loose fare no
better. With 60 different kinds of bacteria in a cat’s saliva, even
a tiny puncture packs a lethal punch.”
Claimed Clark, “People are woefully mistaken if they think
they can turn an injured creature loose and it will survive.”
Clark also stressed in discussion with ANIMAL PEOPLE the fate
of “those who die from the infections associated with the attack that
fails to produce a direct kill. I won’t toss around any assumptions
about the percentage of success cats have in making direct kills,”
Clark said, “but if we apply the generally accepted success rate of
wild predators of one kill in 4 tries, the number of actual cat
victims skyrockets. The true number is certainly much higher than is
currently counted. We receive plenty of birds with missing tail
feathers who have bite or claw marks consistent with a cat attack.”
But Clark missed the obvious: the 600 cat-wounded birds he
sees are among the few who are rescued by humans, typically because
the humans intervene to break off the cat attack. That changes the
predator/prey dynamic. The cat has no opportunity to finish the kill
because of the human intervention.
Otherwise, the injuries he described would impair flight,
and would lead to a cat meal. These are not failures of predation,
but successes, interrupted, comparable to what happens when a hyena
chases a cheetah off a half-dead gazelle and appropriates the meal
The true failures of predation rise into the air and get away
unscathed. The Clark hypothesis that large numbers of birds are
dying in the wild of cat-inflicted injuries and infections is simply
not supported by evidence–whereas, roadkilled birds and the remains
of birds who collide with windows, transmission towers, and power
lines, as well as those who succumb to pesticides, have all been
collected and studied by researchers in bucketloads.
The nonhuman mammal most responsible for declining birds in
the U.S. during the past 20 years is not any predator, but rather
the gentle-mannered Virginia whitetailed deer, whose main food is
“browse,” the brushy hardwood forest understory used as nesting
habitat by most neotropical migratory songbirds.
From the 1950s through the 1980s most states introduced “buck
laws” designed to boost the deer population for the pleasure of human
hunters by exempting does from being hunted. Thus the overwintering
herd came to have a gender ratio sometimes as high as 20 does to one
Because shooting up to 85% of the buck population each fall
made winter browse relatively abundant, more does were able to bear
and raise twin fawns.
By the early 1990s the Virginia whitetailed deer population
was believed to have exceeded pre-Columbian levels, and it has
continued to grow, despite the reintroduction of doe hunting,
increased bag limits, and experiments with contraception.
Comparing the range maps of declining neotropical migratory
songbird species with deer counts confirms the obvious: deer are
eating the birds out of house and home. The only role cats have in
the plight of the birds is that birds unable to find good nesting
habitat sometimes resort to nesting in more vulnerable
locations–where they are exposed to the full range of woodland
Temple & barns
Many of the other common claims about cat predation are
comparably weak. Summarized Ridgley of the findings most often cited
by foes of ferals, “A University of Wisconsin study in the early
1990s found that the estimated 1.4 million to 2 million cats that
range freely in rural areas of the state kill 31.4 million small
mammals and 7.8 million birds a year-at a minimum. ‘We knew the
study would be controversial so we went with the most conservative
estimates,’ says biologist Stanley Temple, coauthor of the study.”
Actually Temple used grossly inflated estimates of cat
numbers. The standard method of estimating the owned cat population,
based on AVMA U.S. Pet Ownership & Demographic Sourcebook data, is
human population divided by 2.65 (people/household), x .568 (ratio
of cats to people).
That would put the owned cat population of Wiscon-sin in the
early 1990s at just under 1.6 million. If feral cats were 40% of
the total cat population, the maximum plausible estimate of the
total number of cats in all of Wisconsin, not just the rural areas,
would have been 1.9 million.
Between ferals and free-roaming pet cats, there were
probably not more than 750,000 free-roaming cats in Wiscon-sin,
barely more than half of Temple’s low-end estimate.
“In parts of rural Wisconsin,” Temple told Ridgley,
“roaming cat densities can reach 114 cats per square mile.”
Yet if every barn in Wisconsin housed feral cats at the
average density of the barn colonies whose populations ANIMAL PEOPLE
surveyed in 1992, when barn colonies appeared to be at their peak
size, the 68,000 barns in Wisconsin would have housed 816,000 cats,
which would work out to 15 cats per square mile.
“The billboard effect”
There is support, however, for the view of San Francisco
quail advocate Alan Hopkins that TNR encourages cat abandonment–a
view shared by DELTA Rescue sanctuary founder Leo Grillo, who
believes that any visible presence of feral cats or feeding stations
creates a “billboard effect” which encourages people to drop cats
off to “give them a chance,” rather than take them to a shelter
where they may be killed.
Overall, pet abandonment was at an all-time high circa 1970,
when U.S. shelters were killing 115 dogs and cats per 1,000 human
residents, about half of them picked up at large. Cats were about
40% of the toll.
By 2002, shelter killing of dogs and cats was down to 15.7
per 1,000 human residents. Cats now account for about two-thirds of
the toll, but the total number of cats killed has fallen from circa
10 million per year to three million per year.
Clearly, the advent of TNR and no-kill sheltering have
reduced abandonment–but not at all sites. Complaints about TNR
programs typically begin when the numbers of cats fail to visibly
drop after several years, and perhaps even increase. Challenged,
the TNR program administrators usually blame abandonment, but resist
the suggestion that the site may be too conspicuous for TNR to
A second valid claim of TNR critics is that the practice of
feeding feral cats changes their hunting behavior from that of wild
predators to that of pets. Birders are often correct in asserting
that the cat toll on wildlife increases after a TNR program starts in
a park or conservation area, partly because feeding the cats means
they need no longer conserve energy, and partly because taking cats
out of the breeding cycle reduces wandering that puts them at risk
from other predators and vehicular traffic.
This means each cat can not only hunt more, but can also
hunts longer–and is among the biggest reasons why ANIMAL PEOPLE has
recommended since 1992 that TNR should not be practiced in sensitve
The Prime Directive
ANIMAL PEOPLE publisher Kim Bartlett was instrumental in
introducing TNR to the U.S.. beginning in 1991 with a seven-month
trial of the method in northern Fairfield County, Connecticut.
Several cats who were removed from inappropriate habitat are still
part of the ANIMAL PEOPLE household.
From the beginning, the goal was to reduce the feral cat population
at the target sites to zero as rapidly as possible.
There are two preconditions for zeroing out a feral cat
colony through TNR, and both were stringently observed:
1) At least 70% of the cats and preferably 100% must be
sterilized. Before the 70% figure is reached, there will be no net
reduction. ANIMAL PEOPLE made every effort to trap and sterilize
100% of the cats at each site as rapidly as they could be identified.
2) The colonies must be monitored to ensure that all
newcomers are identified, caught, and sterilized.
In addition, Bartlett stipulated as fundamental humane
considerations that “All cats and kittens who can be socialized for
adoption should be; no ill, elderly, or disabled cats should ever
be released; all cats should be properly vaccinated”; and, as the
Prime Directive for practicing TNR successfully without rousing
politically problematic opposition, “no cat should be released into
hostile habitat,” such as places of high vehicular traffic, places
where the cats will be obvious to the public and will therefore
attract abandonments, places where the TNR practitioner does not
have permission of the property owner to work, and places where the
neighbors may shoot, poison, or otherwise harm the cats.
“The impact of feral cats on wildlife cannot be ignored,”
Bartlett added in her post-project review, “and should be a major
concern. Feral cats may fit as predators, especial ly in the urban
environment, taking the place of those long gone, but the balance
is delicate. I’m not at all sure how to compare a cat to a fox, but
I suspect the cat will kill many more animals than the fox, mostly
for sport. I’m certain that the predator/prey ratio is askew in
virtually all feral cat colonies. A feral who lives alone would be a
more natural fit.”
Between the Connecticut experiment, which handled 338 cats
in all, and the findings from our 1992 survey of rescuers, ANIMAL
PEOPLE projected that TNR might be suitable in only 12% of the
locations where feral cats are found– but, largely because the 12%
were hospitable to feral cats, they included nearly half the feral
The Florida conflict, and many like it, seem to have
resulted from disregard of the Prime Directive. The outcome of
trying to “save” cats in unsuitable locations may be that not only
those cats but many more will be caught and killed.