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50 The Wildlife Professional, Spring 2011 © The Wildlife Society
On March 2, 2010, in Athens, Georgia, a long-
brewing ght reached City Hall. Legislators
had gathered to vote on an ordinance that
would legalize a trap-neuter-release (TNR) program
to manage the county’s overpopulation of feral cats.
After years of arguments—from scientists opposing
TNR and feral cat advocates endorsing it—the vote
was cast: 9-1 in favor of the ordinance, with an addi-
tional 7-3 vote establishing a $10,000 annual budget
to support the TNR program. It was a resounding
defeat for science—and for wildlife conservation.
How could this happen in a progressive community
like Athens, Georgia, home to one of the nation’s nest
university programs in wildlife science? The answer
is a complex mix of money, politics, intense emotions,
and deeply divergent perspectives on animal welfare.
This victory for TNR—and many others like it across
the nation—marks in part the failure of scientists to
effectively convey the threat that outdoor cats pose to
native wildlife and habitats. If we’re going to win the
battle to save wildlife from cats, then we’ll need to be
smarter about how we communicate the science.
When Pets Become Predators
Domestic cats (Felis catus) are the descendents of
wild cats (Felis sylvestris) native to the Middle East.
Now among the most common pets in the United
States, cats account for a multi-million-dollar outlay
for food and care. Clearly pet cats enrich millions of
human lives. The problem comes when those cats
leave the connes of home and range freely outdoors
or become stray or feral, with dire consequences for
wildlife, biodiversity, and human and animal health.
Now the most abundant carnivore in North America,
cats are recognized by the International Union for
the Conservation of Nature (IUCN) as one of the
“world’s worst” invasive species (IUCN 2008). The
number of outdoor pet cats, strays, and feral cats in
the U.S. alone now totals approximately 117 to 157
million (Dauphiné and Cooper 2009). Their densities
can be extremely high, reaching up to 1,580 cats per
square kilometer in urban areas (Sims et al. 2008).
Instinctive predators, those cats will kill—hungry or
not. A sampling of studies demonstrates the point:
Cats are the single-most signicant invasive spe-
cies affecting birds, with documented impacts on
254 threatened, near threatened, and extinct bird
species worldwide (Butchart 2008).
Cat predation is among the most signicant an-
thropogenic causes of bird mortality in the U.S.,
responsible for an estimated annual death toll of
at least one billion birds (Gill 1995, Dauphiné and
Cooper 2009).
Nearly one-third of the more than 800 species
of birds in the U.S. are en-
dangered, threatened, or in
signicant decline (NABCI
2009), while the number of pet
cats has tripled over the same
period (Lepczyk et al. 2010).
This means that increasing
numbers of cats are preying on
decreasing numbers of birds.
Cats may kill more than twice
as many mammals as birds.
A survey in Great Britain
found that mammals made
up about 69 percent of cats’
prey, birds about 24 percent,
and amphibians and reptiles 5
percent (Woods et al. 2003).
Pick One: Outdoor Cats or Conservation
By Nico Dauphiné, Ph.D., and Robert J. Cooper, Ph.D.
Nico Dauphiné, Ph.D.,
is a Postdoctoral Fellow
at the Smithsonian
Biology Institute,
Migratory Bird
Center, Smithsonian
Credit: Joel Holzman
Credit: Steve Holzman
Stocked with food,
water, and shelter, a
cat feeding station
in Athens, Georgia
provides the comforts
of home for homeless
felines. Though built by
well-meaning cat lovers,
such stations attract
feral and stray cats that
will prey upon native
wildlife and potentially
spread disease.
Robert J. Cooper,
Ph.D., is Professor of
Wildlife Ecology and
Management at the
University of Geor-
gia’s Warnell School
of Forestry and
Natural Resources.
Credit: Clark Jones
© The Wildlife Society
In combination with habitat loss, cat predation
has contributed to wildlife declines and extinctions
worldwide, including the global extinctions of doz-
ens of bird species (Dickman 1996, Brickner 2003,
Nogales et al. 2004). These include the Socorro dove
(Zenaida graysoni), now extinct in the wild, and the
Guadalupe storm-petrel (Oceanodroma macrodac-
tyla), a formerly abundant species that has not been
recorded since 1912 (BirdLife International 2011).
Island-dwelling species are particularly vulnerable.
A survey of 124 oceanic islands showed that cats had
negatively impacted at least 174 endangered verte-
brate species, 71 percent of which were bird species
(Ringler et al. 2010). Likewise, cat predation may
contribute to declines and extirpations of continental
bird populations conned to habitat “islands” such
as parks or open spaces in developed landscapes.
Cats are often the dominant predators in these highly
fragmented systems, where human food subsidies al-
low cats to reach densities that can be exponentially
higher than all native carnivores combined.
In the fragmented landscapes of coastal southern
California, for example, researchers studied how
cats and other predators affected breeding birds in
remnant patches of scrub habitat. They found that
approximately 35 cats patrolled a typical 20-hectare
habitat fragment, killing an estimated 525 birds per
year (Crooks and Soulé 1999). The authors conclud-
ed that this predation was possibly associated with
some of the 75 or more documented local extinc-
tions of birds. Interestingly, the researchers also
found that the presence of coyotes (Canis latrans)
correlated with fewer cats and greater bird diversity.
They believe this was due both to coyotes’ killing
cats and the tendency of cat owners to keep their
pets indoors in areas with coyotes.
Recent studies of urban areas also raise alarms.
Scientists studying gray catbird (Dumetella caroli-
nensis) populations in suburban Washington, D.C.,
found that in areas with high densities of outdoor
pet cats, cat predation caused 79 percent of catbird
nestling and juvenile post-edging mortality, and
that cats appeared to be the main edgling preda-
tors (Balogh et al. 2011). In Florida, researchers
studying the nest success of northern mockingbirds
(Mimus polyglottos ) found that cats accounted for
more than 70 percent of predation events on mock-
ingbird eggs and nestlings in urban areas (Stracey
and Robinson 2010). And scientists in Dunedin,
New Zealand, used models based on empirical data
to suggest that urban areas represent bird popula-
tion sinks due to unsustainable cat predation on
birds (Van Heezik et al. 2010).
As born hunters with
a taste for the great
outdoors, cats will
range widely to prey
on a variety of wildlife
species including
birds, rodents, lizards,
and rabbits (clockwise
from top left). By some
estimates, outdoor
cats in the U.S. on
average kill more than
a million birds a day
and about twice as
many small mammals
and other creatures, an
unsustainable toll.
Credit: Gaetan Priour Courtesy of David Blumig
Credit: Jake Berzon. Credit: Nico Dauphiné
52 The Wildlife Professional, Spring 2011 © The Wildlife Society
Where is the outrage over such slaughter? “There
was a massive public outcry when people witnessed
the effects of the recent Deepwater Horizon oil spill
on birds in the Gulf of Mexico,” says Steve Holzman,
a U.S. Fish and Wildlife Service (FWS) biologist
who helped with disaster response. “Yet cats across
the U.S. kill more than one million birds in a single
day, which is far more than all of the birds killed in
the worst oil spill in U.S. history.” Even so, much of
the public remains silent on cat predation, and most
people do not appear to be aware of the signicant
problems cats pose to wildlife.
The Fallacies of TNR
We believe that public complacency is rooted in the
close relationship between cats and humans, a sta-
tus that often gives cats priority consideration over
wildlife and makes control strategies highly contro-
versial. Recent victories for TNR suggest as much.
On the surface, TNR may sound reasonable, even
logical. Practitioners trap feral cats, neuter them,
re-release them, often into clusters called colo-
nies that receive food, water, and shelter from private
groups or municipalities. TNR cats often receive a
clipped ear as a sign that they’ve been neutered. In
theory, if sterilization rates are high the cat popula-
tion should eventually decline because the sterilized
animals cannot reproduce. Advocates claim that this
approach is a humane alternative to euthanizing
unadoptable feral cats, and, as we saw in the case of
Athens, these arguments can be effective at convinc-
ing local municipalities to adopt TNR.
Advocates of TNR have gained tremendous political
strength in the U.S. in recent years. With millions of
dollars in donor funding, they are inuencing leg-
islation and the policies of major animal-oriented
nonprot organizations (Longcore et al. 2009). The
TNR approach has been legally adopted in at least
10 large metropolitan areas in the U.S., from Miami
to Chicago to San Diego. In addition, unknown
numbers of unofcial or illegal TNR programs ap-
pear to be proliferating as well.
Though TNR may seem reasonable on the surface,
numerous studies have shown that it usually fails to
reduce cat populations due to ongoing cat immigra-
The Ocean Reef Club is a gated community on 2,000 acres at the
northern tip of Key Largo, Florida. It is also home to ORCAT, one of
the oldest and most well-funded trap-neuter-release (TNR) cat colo-
nies in the United States. Ocean Reef citizens founded the colony
in 1993 to curb a severe overpopulation of feral cats, then esti-
mated at about 2,000 animals (ORCAT). Today, the population is
down to about 350 cats. ORCAT supporters consider the program
a success, but conservationists see it quite differently.
Immediately adjacent to Ocean Reef is the last remaining habitat for
two endangered rodent species: the Key Largo wood rat (Neotoma
floridana smalli) and Key Largo cotton mouse (Peromyscus gos-
sypinus allapaticola). They live within the Dagny Johnson Key Largo
Hammocks Botanical State Park and Crocodile Lake National Wild-
life Refuge, together comprising more than 8,000 acres.
Populations of both rodent species have been in steep decline for
years. By 2003, the Key Largo wood rat population had plummeted
to fewer than 100 individuals in the wild (McCleery 2003). Numerous
factors have sped the decline, including development, disease, and
predation by raccoons, rats, and cats. Feral cats were responsible for
77 percent of mortality of wood rats in a recent re-introduction effort
(USFWS 2011).
Concerned about cat predation on endangered species, the Florida
Fish and Wildlife Conservation Commission (FWCC) in May 2003
adopted a “Policy on Feral and Free-Ranging Cats,” supporting “elim-
ination of TNR colonies and similar managed cat colonies wherever
they potentially and significantly impact local wildlife populations.
Likewise, in January 2011 the U.S. Fish and Wildlife Service issued a
draft predator-management plan for the Florida Keys National Wildlife
Refuges Complex, noting that “TNR practices are prohibited on
National Wildlife Refuges, and violate the Endangered Species Act
(ESA) and the Migratory Bird Treaty Act (MBTA) because they may
result in the direct harm of protected species” (USFWS 2011).
It is hard to imagine how anyone could argue that free-ranging
non-native predators should be kept in a colony right next to the last
remaining habitat of endangered rodents. Yet cat advocates have
argued just that. When the FWCC scheduled a hearing on its feral-
cat policy, cat advocates protested so adamantly that the FWCC
sponsored a series of meetings seeking collaboration and con-
sensus. The agency opened the meetings to the public and invited
certain stakeholders who represented cat advocacy organizations,
veterinary professionals, wildlife professionals, and conservationists.
I participated in several of those meetings because of my interest in
wildlife and property law. At a meeting hosted by the Ocean Reef
Resort in June 2004, I learned that the ORCAT colony then had
about 500 free-ranging cats, several paid employees, and an annual
Incompatible Neighbors in the Florida Keys
By Pamela Jo Hatley, J.D.
© The Wildlife Society
Pamela Jo Hatley, J.D., is an attorney in Tampa,
Florida, who focuses on land use and environmental
matters, and a Ph.D. student at the University of
South Florida in the Department of Geography,
Environmental Science, and Policy.
Credit: Clay Degayner
The highly endangered Key Largo wood
rat now lives only in Key Largo, where the
presence of a feral-cat colony threatens the
continued existence of this protected rodent.
operating budget of some $100,000. I then visited Key Largo wood
rat habitat in the nearby Dagny Johnson park, where I observed that
only a chain link fence separated wood rat habitat from the ORCAT
property. In some areas there was no fence at all, giving feral cats
direct access to hunt in that critical habitat.
ORCAT proponents insist that their cats are not contributing to a
decline in the wood rat population. However, I spoke with ORCAT
employees who acknowledged that they were unable to trap and
neuter all cats in the colony, and that unwanted cats were regularly
dumped at the site. Clearly, then, it is impossible to track the com-
ings and goings of all colony cats, let alone determine what they
might prey upon at night.
Park and FWCC employees believe that cats are a factor in the de-
cline of endangered wood rats, and according to the U.S. Geological
Survey, the Key Largo wood rat is so “threatened by development
and predation by feral cats and other predators” that captive-breed-
ing programs may be the only way to save the rodents (USGS). To
that end, federal agencies are engaged in captive breeding programs
for Key Largo wood rats, and private groups such as Disney’s Animal
Kingdom are also breeding and conducting genetic studies on the
species in an effort to save it from extinction (Alligood et al. 2010).
Costly efforts to save this endangered species seem unlikely to suc-
ceed, however, if cat colonies and resulting predation continue.
Allowing cats to roam in natural areas has been compared to “releas-
ing a serial murderer in a ma-
ternity ward” (Pittman 2003).
Equally strong rhetoric
flies from supporters of cat
colonies, no matter the cost
to native wildlife. I believe the
facts speak for themselves. It
is essential to acknowledge
that free-ranging cats are a
significant contributing factor
in pushing certain wildlife
populations toward extinc-
tion. To deny this is unrealis-
tic. To do nothing about it is
tion from surrounding areas. More important, TNR
encourages the notion that cats should be allowed
outdoors, where they prey on native wildlife at will.
All wildlife professionals who are concerned about
this issue can better make a case against TNR by
pointing to the facts:
Fact: TNR does not typically reduce feral cal popu-
lations. One colony in Florida, for example, grew
from 920 to 983 cats over a nine-month period—an
increase of nearly 7 percent (Centoze and Levy 2002,
Winter 2004). Many empirical studies of TNR dem-
onstrate that food provisions attract cat immigration,
often of cats deliberately abandoned by owners near
feeding areas (Hughes and Slater 2002, Castillo and
Clarke 2003, Levy et al. 2003). These factors, along
with births to unsterilized cats, tend to offset popula-
tion declines due to sterilization or deaths from
accidents or disease (Foley et al. 2005, Nutter 2006,
Schmidt et al. 2009).
Fact: Many cats in TNR colonies are not sterilized. A
12-year study of TNR efforts in California and six-year
study of TNR in Florida indicated ongoing cat popula-
tion growth. They estimated that 71 to 94 percent of
cats would need to be sterilized in order to reduce cat
population growth, and noted that actual sterilization
rates were much lower than that (Foley et al. 2005).
Fact: TNR does not reduce predation pressure on
native wildlife. One might assume that sterilized
cats would have small home ranges since they have
no biological need to search for mates. However, a
study of 14 sterilized and 13 intact radio-collared
cats on Catalina Island, California, found no sig-
nicant difference in the size of their home ranges
(Guttilla and Stapp 2010).
Fact: Many TNR programs exist to perpetuate, not
eliminate, feral cat colonies, and many provide feeding
and neutering services without charting popula-
tion changes over time. A description of a three-year
study of a TNR program in Louisiana stated that the
program was designed to stabilize a resident popula-
tion of stray and feral cats “for an indenite period”
(Zaunbrecher and Smith 1993). In a two-year study
of TNR in Texas, organizers stated that their primary
goal was simply to neuter as many cats as possible,
Courtesy of Pamela Jo Hatley
54 The Wildlife Professional, Spring 2011 © The Wildlife Society
The promotion of TNR is big business, with such large
amounts of money in play that conservation scientists oppos-
ing TNR can’t begin to compete. Best Friends Animal Society,
one of the largest organizations promoting TNR, took in over
$40 million in revenue in 2009 (B FAS). The group spent more
than $11 million on cat advocacy campaigns that year, includ-
ing their “Focus on Felines” program, which promoted TNR
and paid for 80,000 tons of dry cat food to feed feral cats. In
FY 2010, the pro-TNR group Alley Cat Allies reports taking in
more than $5 million and spending $3.3 million on public out-
reach, largely to promote TNR and its legalization nationwide
through its “Every Kitty, Every City” campaign (ACA).
Donations range from small contributions of individual cat lov-
ers to large donations and grants supporting TNR initiatives.
In some cases, conservation groups accept funding to join in
efforts promoting TNR. The New Jersey Audubon Society, for
example, had previously rejected TNR but began supporting
it in 2005, acknowledging funding from the Frankenberg and
Dodge Foundations for collaboration with TNR groups (NJAS).
Pet industry giants such as PetSmart and PetCo also fund ac-
tivities to promote TNR, and presumably profit from the huge
amounts of cat food purchased by TNR practitioners. The
global market for pet products—of which pet food represents
about 80 percent—is valued at over $50 billion and has been
growing at roughly 4 percent per year (Combelles 2004, De
Silva and Turchini 2008).
PetSmart recently funded a study that Best Friends commis-
sioned from a for-profit consultancy group to produce a “Feral
Fiscal Impact Calculator,” intended to help TNR advocates
convince municipalities that they will save money by adopt-
ing TNR in place of traditional animal control (AVMA 2010).
Cash-strapped legislators may buy that argument. However,
as veterinarian David Jessup notes, “If you attach even a few
dollars in value to the wildlife killed, and consider the costs of
trying to recover sensitive species, environmental cleanup, and
human health impacts associated with outdoor feral cats, any
hypothetical savings disappear” (Nolen 2010).
What of the value of lost wildlife? One group of researchers
from Cornell University has estimated the economic value of
birds killed by cats. At the time of their study a decade ago,
they estimated that 71 million outdoor cats killed approximately
568 million birds per year in the U.S. (Pimentel et al. 2000,
2005). Based on estimates that bird watchers spent 40 cents
per bird observed, hunters spent $216 per bird shot, and
biologists spent $800 per bird in captive breeding programs
(Tinney 1981, USFWS 1988), the researchers estimated the
economic value of a single bird as roughly $30. That would
equate to a loss of about $17 billion per year from cat preda-
tion of birds.
There are large as yet unquantified costs associated with
nuisance wildlife control of raccoons, skunks, opossums, and
other animals drawn to cat feeding stations. Costs involve the
rehabilitation of wildlife injured by cats, the primary cause of
injury to incoming wildlife reported by some wildlife hospitals
(Jessup 2004, Sallinger 2008). Cat-carried pathogens that af-
fect public health, including rabies, may also lead to potentially
enormous costs borne by private citizens and taxpayers.
Ultimately, the science suggests that cat removal is cheaper
and more effective than TNR for managing large numbers
of feral cats (Loyd and DeVore 2010). However, the cost of
removal is controversy—and that’s a price that many cities and
legislators appear unwilling to pay.
Follow the Money: The Economics of TNR Advocacy
By Nico Dauphiné, Ph.D.
rather than quantify how cat populations responded
to these efforts (Hughes and Slater 2002).
By perpetuating and concentrating feral cat
populations, TNR programs can seriously amplify
impacts on wildlife. Researchers in Hawaii stud-
ied wedge-tailed shearwater (Pufnus pacicus)
breeding colonies located at increasing distances
from a cat feeding area. The closer the birds were
to the cat feeding area, the more likely they were to
be killed, and birds closest to the cat feeding areas
were completely wiped out (Smith et al. 2002).
In a study of native birds and rodents in the
East Bay Regional Park District on California’s
central coast, researchers compared an area
where people were feeding outdoor cats with a
nearby no-cat area (Hawkins et al. 2004). They
found nearly double the number of birds in the
no-cat area compared with the cat-feeding area.
Two native bird species—the California quail
(Callipepla californica) and California thrasher
(Toxostoma redivivum)—were totally absent
from the cat feeding area. In addition, they found
that the number of exotic rodents was nine times
higher in the cat-feeding area, suggesting that cat
predation pressure may be greater on native than
exotic rodents and that provisioning food for cats
may facilitate the spread of exotic rodents into
new areas.
© The Wildlife Society
Problems Beyond Predation
Wildlife professionals who oppose TNR and hope
to convince pet owners to keep their cats indoors
would do well to focus not just on wildlife predation,
but also to call attention to the other problems asso-
ciated with outdoor cats. “I look at the problem as a
box with four sides: cat welfare, environment, public
health, and public nuisance,” says David Blumig, a
New Jersey animal control ofcer with 30 years of
experience dealing with outdoor cats. “You’ve got to
address as many sides as you can.”
Cat Welfare. Many feral cats live short, brutal lives,
with annual mortality rates as high as 80 percent.
The American Veterinary Medical Association has es-
timated the average lifespan of feral cats at two years
as compared with 10 for owned cats (Jessup 2004).
Feral cats suffer considerably higher rates of injury
and disease than their owned counterparts, and are
more likely to succumb to vehicle trauma, predation,
disease, and severe weather (Jessup 2004).
Environment. Owned and feral cats make signicant
contributions to fecal pollution of the environment
and to bacterial loading of streams and coastal waters
(Young and Thackston 1999, Mallin et al. 2000,
Dabritz et al. 2006). In a study of cats in three com-
munities on the central coast of California, researchers
found evidence of substantial fecal contamination,
with 44 percent of owned cats defecating outside more
than 75 percent of the time, and 36 percent of owned
cats defecating exclusively outside. Owned and feral
cats in these communities of about 12,000 households
contributed an estimated 106 tons of feces to the envi-
ronment each year—in an area of less than 30 square
kilometers (Dabritz et al. 2006).
Public and Wildlife Health. The substantial
amount of feline feces in human-dominated en-
vironments raises concerns about the disease
transmission (see articles on page 60 and 64). Fed-
erally endangered Florida panthers (Puma concolor
coryi) have been known to contract feline panleu-
kopenia, or feline parvovirus, an immune deciency
disease (Roelke et al. 1993, Brickner 2003). Passed
through cat feces, the protozoan parasite Toxoplas-
mosis gondii is known to have infected more than
50 bird species worldwide and at least a dozen in the
U.S., including the federally endangered Hawaiian
crow (Corvus hawaiiensis) (Dubey 2002, Work et
al. 2002, Gerhold and Yabsley 2007, Miller et al.
2007). Now the most common domestic animal car-
rier of rabies, cats also can spread pathogens such
as Campylobacter, Salmonella spp., roundworms
Credit: David Blumig
In this gruesome gallery of images (top to bottom), one cat lies dead with a broken
leg, one lies dying in a slimy coat of maggots, and another suffers as ticks and ear
mites plague its face. These are some of the 150 cats that New Jersey animal-control
officer David Blumig was called upon to retrieve last year. Blumig typically takes them
to a shelter for treatment. Those that can’t be cured and adopted are euthanized, a far
better fate than being left to suffer the hazards of life outdoors.
Credit: David Blumig
Credit: David Blumig
56 The Wildlife Professional, Spring 2011 © The Wildlife Society
(or ascarids such as Toxocara cati), hookworms
(Ancylostoma spp.), and protozoan parasites such
as Cryptosporidium spp. and Giardia spp. (Dabritz
et al. 2006). Many of these pathogens potentially
threaten humans as well as wildlife (Work et al.
2000, Danner et al. 2007, Miller et al. 2007).
Nuisance Factor. As feral cat populations
increase, some members of the public begin to
see the animals as an attractive nuisance that
encourages illegal dumping of unwanted animals
(Castillo and Clarke 2003). These cats and their
owned counterparts become vulnerable to abuse
by members of the public fed up with strays roam-
ing their property or stalking their backyard bird
feeders. Indeed, the animal rights group People
for the Ethical Treatment of Animals (PETA) op-
poses TNR on the grounds that it involves cruelty
to both cats and wildlife.
Contention Trumps Conservation
Given such evidence of the harm caused by and
done to feral cats, it’s discouraging that advocates
continue to present TNR to municipalities as a
viable management approach. Public meetings to
discuss TNR can become quite explosive, given
the passions and substantial funding of the pro-
TNR lobby. When the Florida Fish and Wildlife
Conservation Commission unanimously passed
a policy designed to discourage feral cat colonies
that threaten birds and small mammals, angry
protesters accused the commissioners of being
“murderers” and “cat killers” (Jacobson 2003).
On a national scale, pro-TNR groups are increas-
ingly inuencing policy and legislation. For example,
feral cat advocacy group Alley Cat Allies and other
organizations conducted national campaigns in
recent years to pressure FWS to accept cat colonies
in places such as Cape May, New Jersey, and San
Nicolas Island, California, even though such colo-
nies would pose a direct predation threat to federally
threatened and endangered species. The Humane
Society of the United States and other pro-TNR
groups successfully blocked a federal bill (HR 767)
that would have provided funding for the removal of
harmful invasive species from national wildlife ref-
uges on the grounds that feral cats could have been
targeted in these efforts to protect wildlife.
For conservationists concerned about birds and
other wildlife, such relentless devotion to protecting
outdoor cats can be disconcerting, even dangerous.
Feral cat advocates “make no compromises and take
no prisoners,” says New Jersey’s David Blumig, who
has received numerous death threats for his opposi-
tion to TNR. He’s not alone. At the annual meeting of
the American Ornithologists’ Union in 2008, several
scientists reported the same experience. Such intense
passions can force political leaders to bow to the pres-
sure of TNR advocacy groups. Yet in Blumig’s own
New Jersey township, TNR remains illegal—an indi-
cation, perhaps, of the power of one individual like
him, who effectively communicates the facts about
feral cats and says a loud “no” to TNR.
More of us in the wildlife profession need to stand
up and add our voices to the cause. We need strong
leadership coupled with proactive policies and
well-enforced laws that recognize cats as invasive
species, impose nes on owners who refuse to
control their pets, require mandatory sterilization of
pets, prohibit feral cat colonies and feeding stations
especially on public land, and acknowledge the
legitimate role of euthanasia when necessary. Such
measures will go a long way towards protecting the
native wildlife we cherish so much.
For a full bibliography and additional
information about feral cat management,
go to
This article has been reviewed by subject-matter experts.
Credit: Andrew Currie/Creative Commons
Fresh from the hunt, an outdoor cat grips an ovenbird, a neotropical migratory songbird species
that ranges from Canada to South America. Whether a resident species or a long-distance
migrant, any bird within reach of a free-ranging cat may be at risk of predation
a form of
mortality that humans could easily prevent.
58 The Wildlife Professional, Spring 2011 © The Wildlife Society
day at the beach was anything but soothing
for several Miami beachgoers last summer
and fall. Along Miami Beach, at least seven
people developed unsightly rashes caused by hook-
worms crawling under their skin. People affected in
the outbreak contracted the parasites from the feces
of feral cats that use beach pathways and dunes as
litter boxes (Smiley 2010). With seven conrmed
and eight suspected cases of hookworm dermatitis,
Miami-Dade public health ofcials responded to the
outbreak by combing the beach to remove cat feces
and educating beachgoers about how to avoid cat
feces and treat hookworm infections.
This recent case is just one illustration of the poten-
tial for outdoor cats to transmit disease to humans.
Through feces, eas, bites, or scratches, cats can
pass a variety of parasitic, bacterial, and viral ill-
nesses including rabies, toxoplasmosis, typhus,
and plague. With the number of feral cats at epic
proportions, the need for cat control programs is
increasingly a matter of public health.
Historically, animal control programs have been
paramount in minimizing zoonotic risk in the
United States. A rabies control program that began
in the 1950s required mandatory rabies vaccination
in dogs and launched programs aimed at removing
stray and feral dogs to minimize human contact
with potentially rabid animals. These efforts signi-
cantly reduced the incidence of human rabies in the
U.S. Today, however, reports of domestic cat-asso-
ciated rabies exposure and other zoonotic diseases
are warranting increased attention and concern.
Cat Rabies on the Rise
Since 1988, rabies has been detected more fre-
quently in cats than in dogs in the U.S. (Rupprecht
2002). By 2008, the number of rabies cases in cats
was approximately four times the number of cases
in dogs (Blanton et al. 2009). Although rabies
infection is detected most frequently in wildlife
such as raccoons, multiple recent studies show that
human exposure to rabies is increasingly associ-
ated with domestic cats, primarily because people
are more likely to come in contact with cats than
wildlife (Cole and Atkins 2007, Roseveare et al.
2009, Eidson and Bingman 2010). A few examples
illustrate the trend:
From 2002 to 2006 in Georgia, 70 cats tested
positive for rabies, and the virus was detected
more frequently in cats than any other domestic
animal (Cole and Atkins 2007). Moreover, from
2004 to 2006, 17 percent of all conrmed human
rabies exposures in Georgia were due to cat bites,
whereas domestic dogs comprised 5 percent of all
conrmed human rabies cases in Georgia during
the same time period.
An investigation of rabies exposure in domestic
animals in South Carolina showed that stray
cats were disproportionately associated with
potential human rabies exposure and were the
species most frequently reported rabid among
domestic animals exposed to rabies (Roseveare
et al. 2009).
Similarly, in New York from 1993 to 2010, cats
were most frequently associated with human
rabies exposure incidents (32.8 percent) and
post-exposure prophylaxis (PEP) treatments
(31.8 percent) (Eidson and Bingman 2010).
Cats as Carriers of Disease
By Rick Gerhold, DVM, Ph.D.
Rick Gerhold, DVM,
Ph.D., is a post-
doctoral associate
at the Center for
Wildlife Health at
the University of
Credit: Kevin Keel
Pellets of dry food scattered for cats attracts a raccoon to a feeding site in the Florida
Keys. The top vector for rabies in the wild, raccoons can pass the virus to outdoor cats,
which are increasingly the source of human exposure to this dangerous disease.
Courtesy of Timothy Roth
© The Wildlife Society
Rabies virus is transmitted via saliva from one host
to another primarily from bites. The virus replicates
in neurons and disseminates through the nervous
system. Later in the infection, the virus can be found
in highly innervated organs including the cornea,
skin, and salivary glands (Iwasaki 1991). If left
untreated, rabies leads to inammation and de-
struction of brain tissue and an almost certain and
difcult death. Fortunately, prophylactic treatment
is highly effective—but costly: A course of treatment
runs $5,000 to $8,000 per individual, with costs
often borne by public health agencies (Recuanco et
al. 2007). Today, cat exposures to rabies account for
approximately one-third of all PEP treatments in the
U.S. In addition to the cost of PEP, skin infections
due to numerous bacteria (including Pasteurella
multocida, Staphylococcus spp., and Streptococ-
cus spp.) are often associated with cat bite wounds
and often require antibiotic treatment and possible
hospitalization (Talan et al. 1999).
Cats maintained in trap-neuter-release (TNR)
colonies—supported in many places across the
nation—may receive vaccinations against rabies.
However, this does not decrease the need for PEP
treatments because it is impossible to know when
and how feral cats may have been exposed, and
difcult to determine their vaccination status or
to conne them for observation (Jessup and Stone
2010). Furthermore, one study found 22 reported
rabies cases in cats that had been vaccinated,
including in two cats classied as currently vac-
cinated, indicating that vaccine failures can occur
(Murray et al. 2009).
Wild mesocarnivores such as raccoons, skunks,
and foxes—the wildlife species most frequently
infected with rabies in the U.S. (Rupprecht et al.
2001)—are often attracted to the abundant food at
cat colony feeding stations. These outdoor feeding
stations may therefore increase the concentrations
of wildlife and the interface between humans, me-
socarnivores, and cats, leading to an even greater
public health threat due to rabies and other disease
agents associated with wild animals.
For example, some raccoons harbor raccoon
roundworm (Baylisascaris procyonis), an intesti-
nal nematode parasite that has caused morbidity
and death in humans, especially children (Kazacos
2001). Infections occur after exposure to con-
taminated raccoon feces followed by accidental
ingestion of the microscopic roundworm eggs
from the feces. The geographical distribution of
Courtesy of Scott C. Sherman
Credit: City of Miami Beach
A satellite map of part of Miami Beach shows GPS data points indicating cat fecal matter
(green dots) located near feral cat feeding stations (red dots). City leaders commissioned
the map to pinpoint cat-use areas after beachgoers began contracting hookworm
parasites from cat feces in the sand. Unsightly lesions typical of hookworm dermatitis
(below) covered the leg of a patient who developed symptoms after a Florida vacation.
60 The Wildlife Professional, Spring 2011 © The Wildlife Society
B. procyonis is expanding from its historical range
of the midwestern, western, and northeastern U.S.
(Kazacos 2001) to multiple states in the southeast-
ern U. S., Canada, Europe, and Japan (Kazacos
2001, Blizzard et al. 2010, Yabsley et al. 2010). The
discovery of B. procyonis in raccoons near urban
areas in Georgia (Blizzard et al. 2010) is of particu-
lar concern given that feral cat colonies are likely to
be found in urban settings.
Tainted by Toxoplasmosis
Domestic and wild felids are the denitive host for
several zoonotic parasites, including the protozoan
Toxoplasma gondii and the ascarid Toxocara cati.
One study found that the seroprevalence of T. gon-
dii is higher in feral cats than in pet cats, with the
lowest prevalence in cats kept indoors (Nutter et al.
2004). Because T. Gondii oocysts are extremely en-
vironmentally resistant (Long 1990, Kazacos 2001),
infections can occur months or even years after
excretion of the parasite. For this reason, cat feces-
contaminated playgrounds, garden soil, sandboxes,
and other outdoor recreational areas may serve as a
source of infection for humans (Lee et al. 2010).
Contact with infective T. gondii oocysts in cat feces
is found to be a primary risk factor for toxoplasmo-
sis in humans, who become infected primarily by
ingestion of sporulated oocysts from contaminated
soil or water or by ingesting tissue cysts in under-
cooked or raw meat (Elmore et al. 2010). Outbreaks
of toxoplasmosis in communities are often associ-
ated with contaminated water sources. Since tissue
cysts can’t survive outside their hosts, and cats are
the only denitive host that sheds oocysts, these
types of outbreaks have to be cat-feces associated.
Consider the following health implications:
Toxocara cati infections have been associated
with visceral and ocular larval migration and can
result in permanent ocular damage in humans
(Holland and Smith 2006, Lee et al. 2010).
Toxoplasma infections can cause neurological
impairment and can lead to abortions and birth
defects such as hydrocephalus in humans (Dubey
and Odening 2001).
Toxoplasmosis is a dangerous disease for individ-
uals receiving immunosuppressive therapy and is
a major cause of systemic infection and death for
immunosuppressed patients (Elmore et al. 2010).
An increased risk of schizophrenia, autism spec-
trum disorders, and other neuro-inammatory
diseases has been associated T. gondii infection
(Torrey and Yolken 2003, Prandota et al. 2010).
Toxoplasmosis is a major disease issue for wildlife
and has been documented in multiple wild avian
and mammalian species, especially marine mam-
mals Australian marsupials (Dubey and Odening
2001, Dubey 2002, De Thoisy et al. 2003).
Toxoplasmosis is a signicant cause of abortion in
domestic animals including sheep and goats.
Worms, Fleas, and Other Ills
Humans can become infected by several species of
cat-borne hookworms including Uncinaria steno-
cephala, Ancyclostoma tubaeforme, A. braziliense,
and A. ceylanicum (Bowman et al. 2010). Deposited
in feces, hookworm eggs hatch and their infectious
lariform larvae can then penetrate the skin of ani-
mals or human hosts. Infective larvae can cause skin
lesions known as cutaneous larva migrans (CLM) and
less frequently pneumonitis and muscle and ocular in-
fections. Occasionally, A. ceylanicum can develop into
an adult hookworm in humans and cause abdominal
discomfort (Prociv 1998).
The problem is widespread. Several human cases
of feline hookworm infections have been reported
from soil under houses or on beaches where cats
defecate. In Florida alone, one study found that
approximately 75 percent of feral cats were positive
for A. tubaeforme and 33 percent were positive for
A. braziliense (Anderson et al. 2003). In 2006, 22
people were diagnosed with CLM at a Miami-Dade
County children’s camp. Although feral cats were
found in the vicinity of the camp, the source of the
infection was not determined (CDC MMWR 2006).
Ectoparasites of domestic cats, especially the cat ea
(Ctenocephalides felis), are also efcient transmit-
Josh Cook, a veterinary
student at the
University of Georgia in
Athens, scoops beach
sand near a local lake
as part of a research
project to test for the
presence of parasites
passed through cat
feces. By sampling
public-use areas such
as playgrounds and
beaches, Cook and
co-researcher Jessica
Murdock will assess
implications for human
and wildlife health.
Credit: Jessica Murdock
© The Wildlife Society
ters of zoonotic diseases. Three major ea-associated
diseases of cats in the U.S. include cat-scratch dis-
ease (CSD), ea-borne typhus, and plague (McElroy
et al. 2010). CSD, or bartonellosis, is caused by
the gram-negative bacterium Bartonella henselae.
Though cats are the primary source of the bacteria,
they are silent carriers and thus appear healthy. Fleas
acquire B. henselae from the blood of an infected
cat. Infection then passes to an animal or human
when B. henselae-contaminated ea feces comes into
contact with an open wound from a cat scratch or
bite. Prevalence of B. henselae in cats ranges from 15
to 93 percent (Nutter et al. 2004, Case et al. 2006,
Lappin et al. 2006) and feral cats have a signicantly
higher seroprevalence than pet cats (Nutter et al.
2004). Symptoms in humans with CSD include fever,
headaches, weakness, joint pain, and lymph node
enlargement. Chronic CSD cases have manifestations
similar to Lyme disease and can be very debilitating
for infected people. In addition, the disease is one
of the most frequent diagnoses of benign lymphade-
nopathy in children and young adults (McElroy et al.
2010). Atypical complications including encephalitis,
retinitis, and endocarditis occur in 5 to 15 percent of
CSD-infected humans (Chomel et al. 2004).
In addition to CSD, cat eas vector rickettsial diseases
including murine typhus (Rickettsia typhi) and the
closely related zoonotic disease agent Rickettsia felis,
both of which are potential human health threats
wherever cat, rat, or ea populations are dense (Case
et al. 2006). As is the case with CSD, cats are inap-
parent carriers of R. typhi. Outbreaks and potential
outbreaks have been associated with feral cat colonies
(Kliks 2003). Other reported cases of murine typhus
in the U.S. have occurred in central and south-central
Texas and the Los Angeles area (Adams et al. 1970,
Sorvillo et al. 1993). In Los Angeles, 90 percent of
collected cats were seropositive for R. typhi antibod-
ies, whereas no seropositive cats were found in control
areas where no human infections were reported (Sor-
villo et al. 1993). Flea suppression may help protect
public health, but failure to control feral cat popula-
tions could lead to future outbreaks.
Joining the list of cat-related ills, human bacterial
diseases including tularemia, caused by Francisella
tularensis, and plague, caused by Yersinia pestis,
are associated with direct contact with cats or cat
eas (Liles and Burger 1993, Gage et al. 2000,
McElory et al. 2010). Approximately 8 percent of
plague cases in the U.S. are associated with trans-
mission by cats; cases of plague associated with
cat exposure are reported year-round, while ea-
associated cases are generally restricted to warmer
months (Gage et al. 2000). Both tularemia and
plague can cause various disease symptoms such as
painful lymph node enlargement, fever, and chills,
and can potentially lead to fatal respiratory disease.
It is suggested that in addition to harboring infected
eas, cats preying on infected rodents can contain
the bacterial agents of tularemia and plague in their
mouths and potentially transmit the bacteria to
humans via bites or scratches (Elliot et al. 1985).
The Case for Control
Cats may be implicated in other diseases not histori-
cally associated with felines, including H5N1 avian
inuenza, as evidenced by natural and experimen-
tal infection of domestic cats (Kuiken et al. 2004,
Songserm et al. 2006). The experimentally infected
cats excreted virus and transmitted it to H5N1-free
cats, demonstrating horizontal transmission and
suggesting that cats can be involved in epidemiology
and transmission of the virus (Kuiken et al. 2004).
Native predators such as cougars (Felis concolor)
and other wild felids can contract disease by eating
infected domestic cats. Cases of feline leukemia
virus (FeLV) transmitted from domestic cats to wild
felids have been reported in California and Florida
(Jessup et al. 1993, Cunningham 2008). Because
FeLV is a retrovirus that causes immunosuppres-
sion of hosts, infected wild felids have a greater
susceptibility to opportunistic disease agents. In one
case, genetic analysis of the FeLV virus associated
with the deaths of ve Florida panthers showed that
the virus envelope sequence was nearly identical,
indicating that the source of the infection was likely
a single domestic cat (Brown et al. 2008).
Clearly the existence of millions of feral, stray, and
outdoor domestic cats poses a signicant health
risk for humans, pets, livestock, and wildlife.
Wildlife professionals who have difculty convinc-
ing the cat-loving public to control populations of
feral cats might have better luck by emphasizing
the health consequences of cat-borne diseases. One
look at a leg infected with hookworms might be
enough to do the trick.
For a full bibliography and additional
information about cats and disease,
go to
This article has been reviewed by subject-matter experts.
62 The Wildlife Professional, Spring 2011 © The Wildlife Society
California passed a state law in 2005 that
advised pet owners on the proper disposal
of used cat litter. Though the law drew
a few laughs, its intent was dead serious: The
state recognizes that threatened southern sea
otters (Enhydra lutris nereis) are dying from the
Toxoplasma gondii parasite, which originates
in cat feces, washes into the ocean, and con-
taminates the otters’ prey. To help protect water
quality and the threatened sea otter population,
California’s Assembly Bill 2485 asks cat owners
not to “flush cat litter in toilets or dispose of it
outdoors in gutters or storm drains.” Though
responsible pet owners may comply, the law
alone can’t stop the most significant source of
the problem: thousands of pet, stray, and feral
cats defecating outdoors.
By some estimates, up to 70 percent of adult south-
ern sea otters may be infected with T. gondii (Miller
et al. 2002a), a protozoan parasite that can lead
to systemic disease, neurologic impairment, and
death. In some years, T. gondii and related para-
sites kill or contribute to the death of sea otters, and
the parasites have been linked to signicant otter
mortality events. The southern sea otter popula-
tion can ill-afford such an assault. Found only along
the California coast, this federally listed threatened
species now numbers fewer than 3,000 individuals.
Despite more than 70 years of state and federal legal
protection, the population has failed to signicantly
increase its numbers or reclaim large expanses of its
historical range.
Although fecundity appears to be normal, mortality
is extremely high, with approximately 10 percent
of the population found dead each year. A high
proportion—40 to 64 percent—of necropsied south-
ern sea otters have died as a result of exposure
to pathogens and toxins (Thomas and Cole 1996,
Kreuder et al. 2003). Though there are no simple
explanations, evidence suggests that high mortality
and failure of population recovery are associated
with various forms of environmental degradation
and exposure to chemical and biological pollutants
owing from land to sea.
A Parasite’s Deadly Path
Sea otters are near-shore feeders, often foraging
within sight of land and near river mouths and
bays that efciently concentrate and retain plumes
of surface-water runoff (Estes 1997, Jessup et al.
2004 and 2007, Miller et al. 2010a). The otters
often selectively feed on marine and estuarine
invertebrates such as clams and mussels (Tinker et
al. 2008), which are highly efcient bioaccumula-
tors of toxins and organisms ushed into the ocean.
One of the more signicant biological pollutants
that accumulates in bivalves are protozoan para-
sites like T. gondii.
First reported in 1996, T. gondii infections rapidly
became a major focus of sea otter disease research
(Thomas et al. 1996, Fayer et al. 2004, Miller et
al. 2002a, 2002b, 2004, and 2008, Johnson et al.
2009, Massie et al. 2010). This was due in part to a
high level of public interest and to potential human
health implications. While its importance to otter
population recovery may be debated, there is little
doubt that the sea otter-T. gondii connection is one
of the clearest examples ever documented of ocean
pollution by terrestrial-origin pathogens.
The unique life cycle of Toxoplasma gondii is
highly complex (see diagram). Only domestic and
wild felids—including domestic cats, bobcats (Lynx
rufus), and mountain lions (Felis concolor)—are
known to serve as denitive hosts that support
the sexual phase of the parasite’s life cycle. T.
gondii initially reproduces in the lining of cats’
intestines; cats then shed the parasite’s highly
infective oocysts in their feces. The feline host is
able to pass 100 million oocysts in its feces over
10 to 14 days (Conrad et al. 2005), and these
oocysts may remain viable for months or even
years under optimal conditions. By ingesting food
or water contaminated with oocysts, essentially
any warm blooded mammal can become infected.
Invertebrates, like clams and mussels, may act as
paratenic hosts (which simply store the oocysts)
for weeks or months. However, a more common
and efcient means of transmission occurs when
cats or other carnivores ingest an infected inter-
The Trickle-Down Effect
By David A. Jessup, DVM, MPVM , and Melissa A. Miller, DVM, Ph.D.
David A. Jessup,
Dipl. ACZM, CWB,
recently retired
as Senior Wildlife
Veterinarian of the
Marine Wildlife
Veterinary Care and
Research Center
in California and
is now Executive
Manager of the
Wildlife Disease
Courtesy of David A. Jessup
Courtesy of Francesca Batac
Melissa A. Miller,
DVM, Ph.D. , is
a Senior Wildlife
Veterinarian at the
Marine Wildlife
Veterinary Care and
Research Center in
© The Wildlife Society
mediate host (such as a rodent or bird), and its
tissue-cyst stage parasites (Conrad et al. 2005).
The majority of marine mammal infections by T.
gondii are thought to result from oocyst ingestion,
primarily because sea otters and most other marine
mammals rarely, if ever, consume recognized in-
termediate hosts for T. gondii such as rodents and
birds (Thomas et al. 1996, Conrad et al. 2005). The
high level of otter infection suggests that envi-
ronmental contamination by oocysts is extensive
where denitive hosts (cats) are present. Additional
factors such as enhanced parasite infectivity or
pathogenicity, novel host-parasite interactions, and
multiple-species protozoan parasite infections could
also inuence susceptibility in marine mammals
to disease caused by T. gondii (Jessup et al. 2007,
Miller et al. 2010b).
Ingestion of even a single sporulated oocyst can
cause infection in sea otters or other animals
(Conrad et al. 2005). Once ingested, the parasites
leave the intestinal tract and spread systemically.
This may cause serious disease immediately,
but more commonly the effects are delayed. As
host immunity is generated, a “resting stage” is
produced that resides within tissue cysts in the
cytoplasm of host cells. Tissue cysts persist for
months to years, leading to chronic, perhaps life-
long infection. When host immunity wanes later
in life due to other infections, intoxications, or
pregnancy, the parasite can reactivate, leading to
severe clinical disease that destroys portions of
the brain, heart, and other vital organs. This para-
site recrudescence may be an important reason
for the development of clinical toxoplasmosis in
T. gondii-infected marine animals, including sea
otters (Miller et al. 2008, 2010b).
The Science Points to Cats
Based on proximity and sheer numbers, outdoor pet
and feral domestic cats may be the most important
source of T. gondii oocysts in near-shore marine
waters. Mountain lions and bobcats rarely dwell
near the ocean or in areas of high human popula-
tion density, where sea otter infections are more
common. One study of an area around three small
towns near the California coast found that domestic
cats could deposit up to 106.4 tons of feces per year,
or approximately 97 oocysts per square meter of soil
(Dabritz et al. 2007). Area rainfall can wash some of
that contaminated soil into the ocean. In addition,
cat feces from private yards or city gutters can wash
into storm drains that ush into the sea. The use of
The protozoan parasite
Toxoplasma gondii
reproduces in the
intestines of cats
and other felids, the
definitive hosts for the
parasite. Cat feces
carry the parasite’s
infective oocysts into
the environment, where
they can be ingested
by intermediate hosts
(such as birds or
rodents), that may
then infect predators.
When washed into
marine environments,
the oocysts can be
absorbed into filter-
feeding clams and
mussels, which, if
ingested, can infect
sea otters and other
marine mammals.
Credit: Sara B. Miller
Definitive Hosts
Wild or domestic felids
(cats, lions, etc.)
Tissue cysts
from prey muscle, brain,
or other organs
Intermediate Hosts
birds, rodents, humans
Contamination of prey:
filter feeding
or fish?
Fecal contamination
of soil, water, food
Direct ingestion
of oocysts?
Oocysts in feces
Ingestion of
hosts? Otters, manatees,
pinnipeds, cetaceans
64 The Wildlife Professional, Spring 2011 © The Wildlife Society
ushable cat litter may in-
crease the loading of sewage
efuent with T. gondii oo-
cysts. These oocysts are not
killed by traditional sewage
treatment—one impetus for
California’s law discourag-
ing pet owners from ushing
litter and requiring warning
labels on litter sold in stores.
Researchers increasingly
recognize the importance
of terrestrial runoff in the
dissemination of T. gondii
oocysts to humans and marine
mammals (Bowie et al. 1997,
Aramini et al. 1999, Miller
et al. 2002b, 2008). Among
recent studies that highlight
the problem:
Oocysts can contaminate
water or be taken up by
sh (Massie et al. 2010)
and invertebrates
et al. 2001, Arkush et al.
2003, Miller et
al. 2008).
T. gondii oocyst uptake by marine bivalves has
been demonstrated both experimentally (Lindsay
et al. 2001, Arkush et al. 2003) and under natural
conditions (Miller et al. 2008).
Once ingested by invertebrates, T. gondii oocysts
may remain infectious for at least 14 days (Arkush
et al. 2003).
Marine snails, clams, and fat innkeeper worms
also appear to be prey items with a high risk of
infecting otters with protozoan parasites like T.
gondii (Johnson et al. 2009).
Oocysts can sporulate in seawater and remain infec-
tious for at least six months (Lindsay et al. 2003).
Additional studies in central California have iden-
tied high-risk areas for T. gondii exposure and
disease in sea otters, including the Monterey and
Morro Bay areas (Miller et al. 2002b, Kreuder et al.
2003 and 2005, Johnson et al. 2009). Characteris-
tics shared by these high-risk areas include proximity
to more dense human (and cat) populations and to
high-outow creeks, streams, and rivers or to large
enclosed bays with limited tidal exchange (Miller
et al. 2002a and 2002b, Johnson et al. 2009). It is
worth noting that populations of northern sea otters
(Enhydra lutris kenyoni) in Alaska, which have
considerably higher rates of population growth, have
far lower evidence of exposure to T. gondii, presum-
ably because of minimal human population centers,
sparse distribution of feline denitive hosts of T.
gondii, and harsh winter weather, which limits the
overwinter survival of feral domestic felids and leads
to hard freezes that may kill oocysts.
Ecological Dominoes
The health and stability of near-shore marine
ecosystems are dependent on the health and
stability of populations of keystone species that
help structure their habitat. For the kelp forest
communities off California’s coast, the primary
keystone species is the sea otter. Diseases and
other causes of mortality that inhibit normal
population recovery may therefore threaten the
health of the entire ecosystem.
If the cat-related threat to California’s sea otters
and coastal ecosystem isn’t enough to cause public
concern about T. gondii infection, then perhaps
the associated human health implications will raise
the alarm. The evidence is mounting that T. gondii
can cause a variety of human health problems,
notably fetal brain developmental abnormalities
and fulminante systemic and neurologic disease in
immune-compromised people (see article on page
60). Its presence in marine invertebrates consti-
tutes a risk for human communities that harvest
or eat uncooked shellsh. In addition, research-
ers have recently linked T. gondii exposure to a
number of neuro-inammatory diseases, includ-
ing but not limited to autism spectrum disorders,
Alzheimer’s, and Parkinson’s disease (Miman et al.
2010, Pandota 2010, Gulinello et al. 2010).
The scope of this ecological and public health threat
clearly extends far beyond a simple headline that “a
parasite in cat feces kills endangered sea otters.” It’s
fair to say, however, that sea otters, other marine
mammals, near-shore marine ecosystems, and the
health of humans enjoying California’s ocean would
be better served if cat fecal contamination could be
signicantly reduced in the outdoor environment.
Credit: Liz VanWormer
A sea otter swims near a pile of animal feces (likely
a dog’s) on the shore of Monterey Bay in California.
The shot symbolizes a serious threat: When cats
defecate near water, feces-borne parasites that cause
toxoplasmosis can wash into the Bay and and infect
endangered sea otters, a risk to the species’ survival.
To see a full bibliography and additional
resources about toxoplasmosis in marine
environments, go to
This article has been reviewed by subject-matter experts.
66 The Wildlife Professional, Spring 2011 © The Wildlife Society
High on the slopes of Hawaii’s Mauna Loa vol-
cano, National Park Service biologists recently
discovered the mangled remains of three
band-rumped storm-petrels (Oceanodroma castro),
Hawaii’s rarest seabird. Discovered at the end of the
nesting season in the fall of 2010, the birds had been
depredated by feral cats. Band-rumped storm-petrels
are a candidate endangered species, but because of
their extreme rarity, little is known about them (Slotter-
back 2002). Often, the only time these small nocturnal
birds are seen ashore is after they have been killed by
feral cats, the predominant predator in the harsh alpine
environment of the storm petrel’s nesting grounds.
This recent case is just one of many that point to
the severe impact that non-native domestic cats are
having on Hawaiian wildlife. Although there are
no hard numbers on cat populations, clearly many
thousands of cats dwell on each of the Hawaiian
Islands, ranging across all habitat types—from the
ocean to alpine zones, from rainforests to deserts.
The rst domestic cats (Felis catus) did not arrive
in the Hawaiian Islands until Europeans “found”
the remote archipelago in 1778. Never having seen
domestic cats, native Hawaiian people must have
been fascinated by the tame predatory mammals
that served as mousers on ocean-voyaging ships
(Tomich 1986). Cats were taken from the ships and
quickly escaped into the wild, where there was no
other similarly sized competitor. Feral cats ulti-
mately became the most widespread de facto apex
predator throughout Hawai‘i.
The rst known written record of “wild cats” came
from the remote wilderness of Kilauea on the
Island of Hawai‘i (Brackenridge 1841). They soon
became famously abundant in Honolulu, where
Mark Twain described seeing “companies of cats,
regiments of cats, armies of cats…” (Twain 1872).
The effects of these armies on native wildlife soon
became apparent. In 1903, English naturalist
R.C.L. Perkins wrote: “On Lanai, in walking up
a single ravine, I counted the remains of no less
than twenty-two native birds killed by cats.” Many
of the bird species Perkins observed on Lana‘i are
now extinct, as is more than half of Hawaii’s native
avifauna. Although cats are not solely responsible
for these extinctions, they nonetheless have played
a signicant role and continue to decimate Hawaii’s
remaining endemic wildlife, not only by direct pre-
dation, but also by carrying lethal pathogens.
A Mounting Toll on Rare Species
In the dry subalpine woodlands of Mauna Kea, 11
percent of the nests of endangered palila (Loxioi-
des bailleui) are now depredated each year by feral
cats (Hess et al. 2004). That percentage may not
seem extreme, but the toll extends. Adult females
are also killed on their nests, likely explaining
the skewed sex ratio in this forest bird, which is
not adapted to mammalian predation. Moreover,
the nestling development period for the typical
two-chick brood is 25 days, nearly twice the length
of continental species (Banko et al. 2002). This
leaves nestlings vulnerable to predation for nearly
a month. The
compounded effects of cat predation
may be one of
the most easily managed threats
to the continued existence of palila, which are
currently in a precipitous eight-year population
By Land and by Sea
By Steven C. Hess, Ph.D.
Steven C. Hess,
Ph.D., is a Research
Wildlife Biologist
with the U.S.
Geological Survey
Pacic Island
Ecosystems Research
Center in Hawai‘i.
Courtesy of Steven C. Hess
The mangled remains of endangered palila chicks mark the visit of a feral cat. Palila are
endemic passerines that live in dry subalpine woodlands of Mauna Kea, where feral cats
depredate about 11percent of palila nests each year.
Credit: USGS
© The Wildlife Society
decline largely related to habitat loss and drought
(Leonard et al. 2008, USGS unpublished data).
The endangered Hawaiian petrel (Pterodroma
sandwichensis) faces similar threats. Extirpated
from remote alpine nesting grounds on Mauna Kea,
Hawaiian petrels now exist only in small colonies on
Mauna Loa and other islands where these seabirds
are vulnerable to depredation by cats (Simons and
Hodges 1998). The loss of an adult petrel can be
particularly devastating to local populations because
of the species’ delayed maturity. Individuals must
attain ve to six years of age before breeding. They
hatch out single squabs, which must be fed for as
long as 90 days. Petrels locate their nests in burrows
below barren lava, unprotected and exposed to the
vagaries of cats while adult petrels forage far off the
coasts of Alaska and Canada (Adams 2007).
Predation by cats on these two endangered bird spe-
cies has been well documented with remote camera
images and videography. Researchers have also used
telemetry to study the home ranges and activity pat-
terns of cats—and the results are ominous. A study of
radio-collared cats on Mauna Kea shows that males
can range up to eight square miles, rivaling the larg-
est home range of cats anywhere in the world (Hess
and Banko 2006). Most of these long-range wander-
ings oc
cur at night, when birds are settled on their
nests and
therefore more vulnerable to predation.
The Unseen Threat of Disease
Less conspicuous but potentially as harmful
as direct predation are the effects of cat-borne
toxoplasmosis on a host of native wildlife. Fatal
toxoplasmosis has occurred in the endangered
nene or Hawaiian goose (Branta sandvicensis),
the critically endangered Hawaiian crow (Corvus
hawaiiensis), and the red-footed booby (Sula sula)
(Work et al. 2000, 2002). Cat feces that wash
into the ocean may also cause fatal toxoplasmo-
sis in marine mammals (see article on page 64).
Toxoplasmosis has caused the death of at least
one endangered Hawaiian monk seal (Monachus
schauinslandi) on the coast of Kaua‘i (Honnold et
al. 2005), and research shows that T. gondii oocysts
can sporulate in seawater and infect seal and dol-
phin species (Lindsay et al. 2003).
It is impossible to know the extent of infection
and mortality in marine mammals around the vast
waters of the Hawaiian Islands, or even in the ter-
restrial wildlife on Hawaii’s relatively small land
area. Yet the National Park Service, U.S. Geological
Survey, and other federal and state agencies work-
ing in Hawai‘i are so concerned about the potential
disease and predation impacts of feral cats that
they are beginning to install predator-proof fences
and considering the removal of cats from smaller
islands. Such steps may be the last, best hope for
the rare native birds of Hawai‘i.
A researcher attaches
a transmitter to an
anesthetized feral cat
(top) that will later be
tracked (above) as part
of a movement and
home range study on
Mauna Kea. The study
found that the mean
home range for feral
cats at the site was the
second largest reported
in the literature. The
home range for one
male cat was 2,050
hectares, and 610
hectares for a female.
Courtesy of Dan Goltz
Credit: Dan Goltz
To see a full bibliography and ad-
ditional resources about feral cats
in Hawai‘i, go to
This article has been reviewed by subject-matter experts.
68 The Wildlife Professional, Spring 2011 © The Wildlife Society
Microbial oceanography and feral cats seem
about as far removed from one another
as one can fathom. Yet a member of the
U.S. National Academy of Sciences has a passion
for both. Every night this world-renowned scien-
tist drives around the campus of the University of
Hawai‘i at Manoa to feed hundreds of feral cats
out of the back of his car. He spends thousands of
dollars every year on cat food and support for local
feral cat organizations. When asked why, he says,
“Because I care about the cats” (Davis and Lepczyk
2010). Clearly this person cares deeply, but, like
many others, he does so in a manner that is detri-
mental to the environment.
The debate over outdoor cats is often over-sim-
plied as one between people who love cats and
those who don’t, the latter typically assumed to
include wildlife biologists, conservationists, and
ornithologists. In reality, most scientists and
wildlife managers do not hate cats—many fondly
care for pet cats themselves. Rather, they hate what
free-ranging cats do to other species and the envi-
ronment. Thus the debate is predominately about
whether cats should be allowed to run wild across
the landscape, and, if not, how to effectively and hu-
manely manage them. It’s much more about human
views and perceptions than science—a classic case
where understanding the human dimensions of an
issue is the key to mitigating the problem.
A Complicated Bond
Our attitudes towards cats are complex and
diverse, the product of a relationship that is
thousands of years old. Cats are heroes (killers
of vermin, companions) and villains (carriers of
disease, predators of wildlife). They’re enigmatic,
attractive, and amusing. Addressing the problem
of cats therefore requires an understanding of the
cultural, psychological, and socio-economic drivers
that shape peoples’ attitudes and motivations. Un-
fortunately, little research to date addresses these
issues (Van Heezik 2010).
The complexities of the cat problem also serve to fo-
cus our attention on wider issues relevant to urban
conservation management. We need to understand
whether people are even aware of the cumula-
tive impact that their actions—choosing to let cats
outdoors—can have on wildlife populations. Do they
understand the struggles of urban species to survive
where the odds are stacked against them? How
much value do people place on natural diversity in
their environment, and are they conscious of their
own views on what is natural and what is not? Have
they thought about how what they see as their right
to let cats roam freely stacks up against the rights
of other animals to survive? These are difcult
questions that give rise to difcult decisions, but all
people should be exposed to these issues as part of
their formal education.
The cat problem exemplies the disconnect between
humans and nature. Addressing the problem there-
fore requires that wildlife biologists collaborate with
An Issue with All-Too-Human Dimensions
By Christopher A. Lepczyk, Ph.D., Yolanda van Heezik, Ph.D., and Robert J. Cooper, Ph.D.
Christopher A.
Lepczyk, Ph.D., is an
Assistant Professor
of Ecosystem
Management in
the Department of
Natural Resources
and Environmental
Management at
the University of
Hawai‘i at Manoa.
Courtesy of Christopher Lepczyk
Harsh language on a hand-written sign reflects the extreme frustration of a New Jersey
resident angered at finding an unattended litter of kittens at the back of an office complex.
When outdoor cats become over-abundant they can be perceived as a public nuisance,
generating concern about disease, predation, and property damage.
Credit: David Blumig
© The Wildlife Society
social scientists and psychologists, and exert their
inuence politically. Some jurisdictions in Austra-
lia have had success with this approach, where a
combination of legislation and public education has
led to acceptance of strict control measures, such as
indoor connement of pet cats. In many countries,
however, the right to allow cats to roam outdoors
is largely unquestioned and unchallenged. Fur-
thermore, when it comes to exerting inuence, cat
advocates clearly have the edge.
In Athens, Georgia, for example, county commis-
sioners were bombarded with information for
months before voting last year to legalize TNR
(trap-neuter-release) for cat management. Wildlife
professionals who opposed TNR used scientic
literature to make their points, but so did TNR
advocates. In some cases, both sides even cited the
same articles as supporting their positions! The
commissioners were understandably confused and
frustrated (Meyers 2010). It was also obvious that
TNR advocates had been lobbying the commission-
ers (some of whom fed feral cats themselves) long
before anti-TNR conservation scientists entered
the debate. In the end, the professional opinion of
wildlife biologists counted no more than that of any
other citizen, a major reason for the defeat. The
lesson is this: Scientists and others who hope to
convince leaders to favor wildlife conservation over
free-ranging cats should be prepared for a long and
intense confrontation with zealous, committed, and
well-funded cat advocates.
Combating Polarization
Because both sides of the cat debate are fairly
entrenched, it is unrealistic to think that all
stakeholders are going to settle on a single unied
approach to address the cat problem. However,
there are ways to move forward (Lepczyk et al.
2010). One approach is exemplied in Hawaii,
where we’ve become part of a large coalition of
stakeholders working together with the shared
goal of reducing and eventually removing feral
cats from the landscape.
Our diverse group includes individuals from the
Humane Society of the United States, the Hawaiian
Humane Society, the U.S. Fish and Wildlife Service,
the National Park Service, Hawaii’s Department of
Land and Natural Resources, and the University
of Hawaii. Our team also regularly interacts with
other groups around the nation such as regional
Audubon Societies and the American Bird Con-
servancy. Several stakeholders in the group have
differing views, such as on whether or not eutha-
nasia or culling is appropriate, or whether people
should feed feral cats. However, the coalition
has agreed to certain broad actions, such as rst
addressing feral cat colony issues in locations
with critical habitat for endangered species, and
acknowledging the need to address the social and
legal aspects of responsible pet ownership. Overall,
the notably positive aspect of this group is that a
shared goal exists of ultimately removing cats from
landscape. This common purpose enables us to
collaborate on solutions and keep moving forward.
Working groups such as this are essential given
that the issues related to outdoor cats are so diverse
and emotional. Activists on both sides of the issue
too often present polarized viewpoints that only
obscure the truth and exaggerate the divide. In
Wisconsin in 2005, for example, cat advocates
protested angrily when free-ranging cats were
legally reclassied as a non-native species (Lepczyk
2005). Likewise, the views published on many pro-
feral cat websites are often vitriolic and demonize
opponents, which can simply iname scientists
and wildlife managers. And though TNR advocates
often claim that public opinion favors TNR over the
lethal control of feral cats, there is little evidence
to support this claim; in fact, the vast majority of
the public is generally apathetic or ignorant of the
Yolanda Van Heezik,
Ph.D., is a Senior
Lecturer of Zoology at
the University of Otago
in Dunedin, New
Robert J. Cooper,
Ph.D., is Professor of
Wildlife Ecology and
Management at the
Warnell School of
Forestry and Natural
Resources, University
of Georgia
Fit for pampered felines,
outdoor enclosures
such as this in New
with fans, lighting,
climbing structures, litter
boxes, and snug ‘cat
houses’—allow doting
pet owners to give
cats fresh air without
allowing them to roam
freely. Such containment
could help solve the split
between cat lovers and
Credit: Pawtrait Persians
70 The Wildlife Professional, Spring 2011 © The Wildlife Society
issues regarding free-ranging cats (Ash and Adams
2003). Without concerted effort to work on the
problem in a professional, collaborative manner
that acknowledges all the differing viewpoints, the
debate is likely to become more divided and nega-
tive, resulting in lawsuits rather than solutions.
Because the debate over free-ranging cats is much
more about conicts in human values and emo-
tions than science, we must use a multi-pronged
approach to making progress. This requires focus-
ing on three main means to move forward: legal or
policy changes, incentives, and increased educa-
tion (including extension). For these approaches
to be most effective, they will require collaborative
partnerships such as the one in Hawaii. Considering
the rapid rise in the numbers of pet cats (Lepczyk
et al. 2010), which is likely mirrored by increases in
feral cats, it is critical to increase all of these efforts.
According to McGill University wildlife biology
professor and avian expert David Bird, changing
attitudes towards feral cats is likely to take 50 years,
so it’s high time we got started.
In New Zealand, there are no regulations to limit the free-
ranging behavior of cats or the number of cats that people
can own. I find this extraordinary in a nation that directs
enormous conservation efforts towards control of other
introduced predators. New Zealanders are generally very
pragmatic, even enthusiastic, about controlling mustelids,
rats, or brushtail possums to protect native biodiversity. Yet
domestic cats have remained under the radar, despite nation-
wide media coverage of cats preying on native wildlife.
Part of the problem is that the “cat issue” is seen more as
a question of public nuisance or cat welfare than of wildlife
conservation. That was clear when I approached my own city
council to outline the impacts of cat predation and discuss
mitigation measures such as 24-hour cat confinement and
designated no-cat zones. The response was incredulity.
finement of cats is considered unnatural and cruel.
Most publically acceptable mitigation measures to reduce
cat predation serve only as sops for our conscience and
prove ineffective or baseless. For example, some guidelines
suggest keeping a cat well-fed, yet there is no evidence
that this curtails predation. Some suggest keeping cats
indoors at night, though that doesn’t protect diurnal spe-
cies such as birds and reptiles. Registering and micro-
chipping cats can distinguish between pets and strays, yet
that’s irrelevant in terms of predation. Collar-mounted bells,
bibs, and sonic devices can reduce catch rates but don’t
eliminate the problem.
Cat-free zones around areas of conservation concern are
equally well-meaning but probably ineffective. When we
investigated how large such zones would need to be to ef-
fectively exclude cats, we found that cats expand their home
ranges to fill available space, covering tens of hectares in ru-
ral areas (Metsers et al. 2010). Clearly 24-hour confinement
of cats inside homes or backyard enclosures is the only truly
effective measure to stop cats from catching wildlife.
A fundamental problem behind calls for such cat regulation
is the lack of studies conclusively showing that urban pet
cats are responsible for wildlife declines. Many studies show
that cats collectively kill large numbers of prey, and that cats
exist in high densities of between 200 to 1,580 per square
kilometre in urban areas. However, it’s unclear to what extent
declines in wildlife can be attributed to cats versus other
human-related modifications to urban landscapes. Such data
are difficult to obtain because it is not feasible to manipulate
cat ownership for study purposes, and research around new
sub-divisions with cat regulations are likely to be hampered
by difficulties of replication and habitat matching.
If a precautionary approach is adopted in the absence of sol-
id evidence, some understanding of public attitudes towards
cats and control measures is necessary. My impression is
that cat owners in New Zealand are unaware of the cumula-
tive impacts of cat predation, so owners will be reluctant to
accept that their pets should be regulated. In addition, many
people don’t perceive urban areas as a home for wildlife. Un-
less we can foster a greater awareness and appreciation of
urban wildlife, the bottom line for most people will be prefer-
ence for their feline friends over native species.
By Yolanda Van Heezik, a Senior Lecturer of Zoology at the
University of Otago in Dunedin, New Zealand.
A New Zealand Perspective
For a complete bibliography,
go to
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72 The Wildlife Professional, Spring 2011 © The Wildlife Society
Seeing the Light in Green Fire
By Michael Hutchins
Green Fire, a new documentary about the life
and legacy of Aldo Leopold, should be man-
datory viewing for any student in a natural
resource eld, indeed for anyone who values nature,
wilderness, and wildlife. Directed by Steve and Ann
Dunsky and Dave Steinke of the U.S. Forest Service,
the lm aspires to “change hearts and reshape hu-
man behavior” by bringing Leopold’s conservation
message to the world. That’s an ambitious goal, but
Green Fire goes a long way toward achieving it.
Released in February 2011, the 70-minute docu-
mentary recounts the key experiences that shaped
Leopold’s world view and led him to develop the
“Land Ethic,” a cornerstone of the modern conser-
vation movement. Structured in the manner of all
compelling documentaries, the lm integrates his-
torical and modern photographs, lm clips, music,
narrated quotes from Leopold, and interviews with
Leopold family members and respected conserva-
tionists and others who have been inuenced by
Leopold’s writings. Curt Meine—Leopold’s primary
biographer and one of the world’s foremost experts
on the man and his legacy—serves as the lm’s main
on-screen source, a credible guide to the evolution
of Leopold’s thinking.
Even those who have read a great deal by and
about Leopold over the years will gain new in-
sights about his life through this lm. We learn
that Leopold’s rst binoculars were opera glasses
borrowed from his mother, Clara, who taught
him observational skills and a sense of aesthetics.
We see Leopold as a young hunter on horseback
proudly displaying his quarry. We hear excerpts
of his courtship letters to Estella, his future wife,
a woman with Spanish roots and whose family of
prominent sheep herders contributed to the over-
grazing of western landscapes. We watch Leopold’s
career evolve from forester to conservationist to
esteemed professor, and we witness the simple
pleasures he shares with Estella and their ve chil-
dren as they transform a windowless chicken coop
into a treasured retreat in the pines of Wisconsin—
the revered Leopold Shack.
I especially liked the lm’s depiction of how
Leopold’s philosophy changed over time. This is
poignantly shown when the lm explores what Meine
calls “a fateful turning point” in Leopold’s life—the
now-famous moment when Leopold shot a wolf in
the Apache National Forest of the U.S. southwest.
Decades later, in his essay “Thinking Like a Moun-
tain,” Leopold described watching “the erce green
re dying in her eyes,” a moment that began to trans-
form his thinking. After having practiced predator
control across the West, Leopold began to observe
the ecological devastation that followed when over-
hunting depleted predators to the point that their
prey became overabundant. He subsequently saw the
need to balance all elements of nature—soil, water,
plants, animals, and the human community—for the
good of the whole and for future generations. Thus
the “Land Ethic” was born in a wolf’s dying eyes.
Credit: TK
Michael Hutchins,
Ph.D., (at the
Leopold Shack
in Wisconsin) is
Executive Director/
CEO of The Wildlife
Courtesy of Michael Hutchins
© The Wildlife Society
A Relevance that Endures
One of Leopold’s rst experiments with a holistic ap-
proach to land occurred in the 1930s in Coon Valley,
Wisconsin, at that time an over-farmed region devas-
tated by massive soil erosion and ooding. Leopold
worked with local landowners to regenerate the soils,
plant trees, and manage crops and wildlife in ways that
would restore health to the land—an effort that became
the nation’s rst watershed-scale restoration effort,
or what Meine calls “a revolution in conservation.”
Likewise, as head of the University of Wisconsin Arbo-
retum, Leopold led the effort to collect sod and seeds
to restore a prairie ecosystem using techniques that
conservationists still use today. Through such efforts
Leopold became the father of ecological restoration.
Green Fire shows how that legacy continues to inu-
ence conservationists in ways both large and small.
We see, for example, a restoration project in inner-
city Chicago, where conservation educator Michael
Howard teaches children to plant seeds and grow
vegetables on a restored patch of ground that was
once an illegal dump site. “It’s amazing what you
can do on a little bitty space trying to reconnect the
community back to the land,” says Howard. Leopold
couldn’t have said it better himself.
For all its strengths, the lm does have some signicant
aws of omission. It makes no reference to contem-
porary challenges that threaten the Land Ethic and
everything it stands for. One of the main challenges
comes from radical animal-rights philosophy, which,
with its narrow focus on the “rights” of individual
sentient animals, is in fundamental opposition to the
more holistic Land Ethic, which recognizes the inter-
dependencies among land, wildlife, and plants—and
the human responsibility to manage these for over-
all ecological health. Another challenge comes from
the introduction, both purposeful and accidental, of
non-native species, which are transforming natural
landscapes and threatening the existence of many
native plants and animals. Animal-rights proponents
frequently oppose the control of destructive non-native
animals, but Leopold was quite clear on this matter,
calling it a “self-evident principle” that “native species
should be given preference in management.”
My nal concern with the lm is that although it
devotes attention to Leopold’s role in founding the
Wilderness Society, it barely touches on his funda-
mental role in establishing the wildlife profession,
and makes no mention of his founding role in The
Wildlife Society. Since many of us are students of
Leopold’s work—particularly his seminal text Game
Management—this omission is discouraging.
That said, Green Fire remains a moving portrait of a
visionary man. Though Leopold died in 1948, many
of his writings are just as relevant today—if not more
so—than they were in his own time. Coming full circle,
the documentary ends with scenes of wildlife restora-
tion almost undreamed of in Leopold’s day but made
possible by his pioneering work. We see ocks of
sandhill cranes—nearly extinct in the 1940s—soaring
again over a Wisconsin marsh. We see a Mexican wolf
being reintroduced into the southwestern wilderness,
a symbol of the remarkable comeback of “green re”
across the nation. And we see how a genuine connec-
tion to nature enriches human lives.
Nowhere was Leopold’s personal connection to the
land more evident than on the property he bought and
restored in Wisconsin and immortalized in his book A
Sand County Almanac. Leopold lived what he be-
lieved: that private landowners have a responsibility for
stewardship and an obligation to live in harmony with
nature. Watching how Leopold’s entire family derives
joy from their modest shack and the surrounding
landscape, and having visited the shack myself, I can
understand why it has become an important symbol for
conservation today. Its core message: The key to human
happiness is not material wealth, but rather a close and
intimate connection to the land, wildlife, nature, and
each other. As Leopold’s daughter Nina says in the lm,
the shack serves as “a metaphor of how one can nd
absolute happiness with the least amount of stuff.”
One of the lm’s most powerful images comes toward
the end when we see the singed contents of the wallet
that Leopold was carrying on the day he died of a heart
attack while helping a neighbor ght a re. As tragic
as his death was, it seems almost tting that Leopold
died helping another care for land they both loved.
With such poignant details, this lm is a ne tribute to
Leopold’s legacy. While his writings will continue to be
the most important source of information on Leop-
old’s Land Ethic, Green Fire will contribute to people’s
appreciation of this amazing man and his role in the
history of the conservation movement.
To see a clip from the film Green Fire
and a schedule of film viewings,
go to
... The capturing of feral animals to neuter them and subsequently release them back into the feral state, typically referred to as Trap-Neuter-Return (TNR), is increasingly being advocated as a humane and effective option for cat control (Kreisler et al., 2019;Spehar & Wolf, 2018;. However, there are many problems with the TNR-approach to cat management (see Dauphiné & Cooper, 2011;Hostetler et al., 2020 for comprehensive reviews). For instance, unmanaged feral cat populations can be subject to a wide variety of conditions deleterious to their health caused by the lack of preventative or emergency care and the consumption of garbage (Crawford et al., 2019;Hostetler et al., 2020). ...
... It has now been more than 10 years since Longcore et al. (2009), Lepczyk et al. (2010, and Dauphiné & Cooper (2011) commented on the lack of leadership within the conservation and research community regarding the practice of cat TNR and the need for a more effective response to its promotion as effective and humane. The calls for conservation leadership were, in and of themselves, not really surprising since scientists (including conservation scientists) have long experienced barriers that not only tend to disengage them from ethical and societal implications of their work (McCormick et al., 2012) but also from the need to effectively communicate their results to society (Van Vliet et al., 2014). ...
... Lepczyk et al. (2010) even foresaw that "it may well be a generation or more before we can expect broad-scale changes in human behaviour regarding outdoor cats." While TNR is (fortunately) most-often proposed for cats in urban and metropolitan areas, it is or has also variously been promoted or implemented in environmentally sensitive areas such as Cape May, New Jersey, San Nicholas Island, California, and Key Largo (Dauphiné & Cooper, 2011), or, for example, on the Caribbean island of Saba, adjacent to critical Red-billed tropicbird (Phaethon aethereus) breeding colonies (Debrot et al., 2014;Terpstra et al., 2015;Boeken, 2016). ...
Full-text available
It has been 10 years since a seminal paper in the journal Conservation Biology called for stronger leadership from the conservation community in countering the growing inappropriate use of Trap‐Neuter‐Return (TNR) as a method to control feral cat, Felis catus, populations. The practice is rapidly spreading to areas of wildlife and conservation significance, and the need to counter this development is extremely urgent. So far, the promulgation of TNR has been based on a narrow, single‐species approach to animal welfare. However, a new, yet little‐noticed, species‐inclusive perspective on animal welfare includes the consideration of collateral animal suffering for a more equitable assessment of TNR. Each setting, depending on the level of conservation required, may call for different methods for the management of free‐roaming cats. TNR is just one such method and its appropriateness depends on the specific wildlife conservation needs for each area specified.
... This is the largest human-influenced source of mortality in wild birds and mammals (Loss et al 2012). In the United States, there are also 117-157 million pet, stray, and feral cats (Felis catus) (Dauphine and Cooper 2011). The United States has approximately 70 million pet dogs (Canis familiaris) (AVMA 2012). ...
... Domestic cats (hereafter referred to as cats) have been directly linked to the extinctions of 40 bird, 21 mammal, and two reptile species (Doherty et al 2016). Cats are now the most abundant carnivore in all of North America, outcompeting native mesopredators such as striped skunks (Mephitis mephitis) and northern raccoons (Procyon lotor) (Dauphine and Cooper 2009;Dauphine and Cooper 2011). Abstract: Invasive species pose a threat to native wildlife species worldwide. ...
... Breeding season for the majority of native wildlife is between March and August (Gode and Ruth 2010). 4. With reports of up to 1580 cats/km 2 in urban areas in the US, greater intakes of cat-and dog-attacked patients will be from urban areas (Dauphine and Cooper 2011). Greater cat density in urban areas will offset the fact that rural cats are often allowed outdoors for longer periods of time (Ancillotto et al 2013). ...
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Invasive species pose a threat to native wildlife species worldwide. Through predation, competition, disturbance, hybridization, and disease transmission, invasive mammals interrupt natural ecosystem functions. Domestic dogs and cats affect wild populations of mammal, avian, and reptile species. Wildlife rehabilitation centers accept wild animals as patients for treatment after they have had contact with a domestic animal with the goal of releasing them back into the environment. The authors’ objective was to evaluate the impacts of domestic cats and dogs on small mammals and birds located in south central Pennsylvania. Wildlife rehabilitators rely on the public to bring them injured animals. Species bias exists among rescuers, as such, this study was not a comprehensive assessment of the problem in Pennsylvania. Survival of patients admitted to Raven Ridge Wildlife Center in Lancaster County, PA between July 2015 and June 2016 was analyzed based on species, reason for admission, location, and season. Survival of patients who had been attacked by cats was significantly lower than those admitted for any other reason. Cats and dogs impacted 23 species, including three rabies vector species. Eastern cottontails accounted for a majority of cat and dog attacks. Moreover, no admitted avian species survived a dog or cat attack on any occasion. Attacks by both dogs and cats increased during breeding season (March–August) for many species, with most attacks occurring in urban areas. Care for wildlife injured by dogs and cats cost Raven Ridge Wildlife Center an estimated $7,557.00 in one year. Wildlife rehabilitators should focus on reducing the likelihood of these attacks through public outreach. Both cat and dog attacks occurred near locations identified as important breeding habitat for threatened or endangered birds, making prevention of these events a priority.
... In the years since Foley et al. [22] was first published, some critics of TNR have cited the analysis to support the claim that TNR is ineffective at reducing the population of freeroaming cats [18,[25][26][27][28]. Others go further, arguing that the study is evidence of population increases despite long-term TNR efforts [17,[29][30][31]. ...
... Foley et al. [22] reported critical neutering rates (71-94%) "far greater than what was actually achieved", a point subsequently used by some critics of TNR to argue that the management scheme is infeasible [17,29]. It is important to note, however, that this is a cumulative sterilization rate-typically the result of TNR efforts spanning several years. ...
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In a frequently cited 2005 paper, a Ricker model was used to assess the effectiveness of trap–neuter–return (TNR) programs for managing free-roaming domestic cat populations. The model (which was originally developed for application in the management of fisheries) used data obtained from two countywide programs, and the results indicated that any population reductions, if they existed, were at best modest. In the present study, we applied the same analysis methods to data from two long-term (i.e., >20 years) TNR programs for which significant population reductions have been documented. Our results revealed that the model cannot account for some key aspects of typical TNR programs, and the wild population swings it predicts do not correspond to the relative stability of free-roaming cat populations. A Ricker model is therefore inappropriate for use in assessing the effectiveness of TNR programs. A more recently developed, stochastic model, which accounts for the movement of cats in and out of a given area, is better suited for predicting the sterilization effort necessary to reduce free-roaming cat numbers through TNR programs.
... Critics of TNVR often use the "elimination" of colonies as a kind of litmus test for measuring its success or failure (Dauphiné & Cooper, 2011;Jessup, 2004;Lepczyk et al., 2015;Longcore et al., 2009). However, as the eradication programs described above illustrate, the complete elimination of cats even from small, isolated islands is a considerable challenge. ...
Citizens expect local elected and appointed officials to make, implement, and evaluate public policy. In recent years, citizen efforts to increase the number of companion animals leaving U.S. animal shelters alive have received considerable attention from animal welfare advocates, the mainstream media, and policy makers. Among the greatest challenges for urban shelters, where the most unowned, free-roaming cats are found, is how best to manage “community” cats. Three policy options have been identified: eradication; impoundment followed by lethal injection of cats not adopted (sometimes referred to as “trap-and-kill”); and trap-neuter-vaccinate-return (TNVR). Since governments at the state and local level are directly involved in any policy or decision-making strategy to manage community cats, public opinion and taxpayer-funded initiatives are important factors in policy making, especially in light of the recent push for “no-kill” animal shelters (i.e., where live outcomes are provided for 90% or more of the animals entering a facility). With eradication infeasible and no evidence that “trap-and-kill” is an effective means for reducing the populations of these cats, policy makers are increasingly turning to TNVR programs.
... The most striking example of this cognitive dissonance is the attitude of cat owners towards the impact of their pet on biodiversity [136][137][138][139]. Whilst they care about the welfare of their cat and of cats in general, they show less concern for the animals that are injured or killed by their cat [140] and by the consequent loss of biodiversity [141,142]. In this moral schizophrenia [143,144], concern for biodiversity and other animals can never exceed the pet owners' compassion for cats [145]. The relationships owners develop with their pets increase levels of oxytocin, which in turn directly influences on empathy and anthropomorphism. ...
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Anthropomorphism is a natural tendency in humans, but it is also influenced by many characteristics of the observer (the human) and the observed entity (here, the animal species). This study asked participants to complete an online questionnaire about three videos showing epimeletic behaviours in three animal species. In the videos, an individual (a sparrow, an elephant and a macaque, respectively) displayed behaviours towards an inanimate conspecific that suddenly regained consciousness at the end of the footage. A fourth video showed a robot dog being kicked by an engineer to demonstrate its stability. Each video was followed by a series of questions designed to evaluate the degree of anthropomorphism of participants, from mentaphobia (no attribution of intentions and beliefs, whatever the animal species) to full anthropomorphism (full attribution of intentions and beliefs by animals, to the same extent as in humans) and to measure how far the participants had correctly assessed each situation in terms of biological reality (current scientific knowledge of each species). There is a negative correlation (about 61%) between the mental states attributed to animals by humans to animals and the real capability of animals. The heterogeneity of responses proved that humans display different forms of anthropomorphism, from rejecting all emotional or intentional states in animals to considering animals to show the same intentions as humans. However, the scores participants attributed to animals differed according to the species shown in the video and to human sociodemographic characteristics. Understanding the potential usefulness of these factors can lead to better relationships with animals and encourage a positive view of human-robot interactions. Indeed, reflective or critical anthropomorphism can increase our humanity.
... The most striking example of this cognitive dissonance is the attitude of cat owners towards the impact of their pet on biodiversity [136][137][138][139][140]. Whilst they care about the welfare of their cat and of cats in general, they show less concern for the animals that are injured or killed by their cat [141] and by the consequent loss of biodiversity [142,143]. In this moral schizophrenia [144,145], concern for biodiversity and other animals can never exceed the pet owners' compassion for cats [146]. The relationship owners develop with their pets increases levels of oxytocin, which in turn directly influences on empathy and anthropomorphism. ...
Full-text available
Anthropomorphism is a natural tendency in humans, but it is also influenced by many characteristics of the observer (the human) and the observed entity (here, the animal species). This study asked participants to complete an online questionnaire about three videos showing epimeletic behaviours in three animal species. In the videos, an individual (a sparrow, an elephant and a macaque, respectively) displayed behaviours towards an inanimate conspecific that suddenly regained consciousness at the end of the footage. A fourth video showed a robot dog being kicked by an engineer to demonstrate its stability. Each video was followed by a series of questions designed to evaluate the degree of anthropomorphism of participants, from mentaphobia (no attribution of intentions and beliefs, whatever the animal species) to full anthropomorphism (full attribution of intentions and beliefs by animals, to the same extent as in humans) and to measure how far the participants had correctly assessed each situation in terms of biological reality (current scientific knowledge of each species). There is a negative correlation (about 61%) between the mental states attributed to animals by humans and the real capability of animals. The heterogeneity of responses proved that humans display different forms of anthropomorphism, from rejecting all emotional or intentional states in animals to considering animals to show the same intentions as humans. However, the scores participants attributed to animals differed according to the species shown in the video and to human socio-demographic characteristics. Understanding the potential usefulness of these factors can lead to better relationships with animals and encourage a positive view of human-robot interactions. Indeed, reflective or critical anthropomorphism can increase our humanity.
... Critics of TNVR often use the "elimination" of colonies as a kind of litmus test for measuring its success or failure (Dauphiné & Cooper, 2011;Jessup, 2004;Lepczyk et al., 2015;Longcore et al., 2009). However, as the eradication programs described above illustrate, the complete elimination of cats even from small, isolated islands is a considerable challenge. ...
Citizens expect local elected and appointed officials to make, implement, and evaluate public policy. In recent years, citizen efforts to increase the number of companion animals leaving U.S. animal shelters alive have received considerable attention from animal welfare advocates, the mainstream media, and policymakers. Among the greatest challenges for urban shelters, where the most unowned, free-roaming cats are found, is how best to manage “community” cats. Three policy options have been identified: eradication, impoundment followed by lethal injection of cats not adopted (sometimes referred to as “trap-and-kill”), and trap-neuter-vaccinate-return (TNVR). Since governments at the state and local level are directly involved in any policy or decision-making strategy to manage community cats, public opinion and taxpayer-funded initiatives are important factors in policy making, especially in light of the recent push for “no-kill” animal shelters (i.e., where live outcomes are provided for 90% or more of the animals entering a facility).
... In the present study, concerns about pest animal welfare and management methods were not perceived as a difficulty by officers, although they have become an increasing issue globally (Bertolino and Genovesi 2003;Dauphiné and Cooper 2011;Nagamine 2011;Oi et al. 2014;Estévez et al. 2015). ...
Context In Japan, the raccoon is an invasive, non-native mammal that causes significant agricultural damage and impacts on native biodiversity throughout the country. Local governments are mainly responsible for raccoon management. Intensive control campaigns focused on the early invasion stage have controlled raccoons in some regions but, generally, there are very few regions where raccoon numbers have been reduced sustainably, and no raccoon populations have been eradicated. Aims To improve national management of raccoons and canvass the opinions and perceptions of local government officers involved in raccoon control, and to review the efficiency and effectiveness of raccoon management strategies. Methods A questionnaire survey of 47 prefectural and 366 municipal governments was conducted, regarding raccoon management measures, during 2012 and 2013. The survey covered two topics: (1) management difficulties experienced by officers; and (2) details of the current raccoon management regime. Key results Efforts to manage raccoon populations have encountered some difficulties, including shortages of raccoon control officers, funding, expertise in raccoon biology and management, and lack of information about the invasion status of local raccoon populations and ecological traits of raccoons. Prefectures not currently managing raccoons indicated that they suffered from a lack of appropriate management procedures. However, current management programs were not generally functioning efficiently or effectively because many local governments did not implement appropriate monitoring. About 70% of local governments did not set control target indices, and there were very few quantitative datasets that could be used to measure the effectiveness of control in reducing raccoon impacts. Conclusions Best practice management programs have been being implemented in very few government areas, with institutional characteristics and difficulties in obtaining relevant information causing major problems. Implications Collecting and sharing information about effective raccoon management methods and case study examples from successful regions would enable other local administrations to select and implement the most effective and efficient control strategy, methods and monitoring program for their region.
In this study, we asked participants to answer an online questionnaire about videos showing animal epimeletic behaviours: an individual (a sparrow, an elephant and a macaque) displayed behaviours towards an inanimate conspecific who suddenly got back to conscious at the end of the footage. A fourth video showed a dog-robot kicked by an engineer to demonstrate its stability. After each video, questions were asked to score the degree of anthropomorphism of participants, from mentophobia (no attribution whatever the species) to full anthropomorphism and to measure how close participants are to biological reality (actual scientific knowledge). A first important result is that there is a negative correlation (about 61%) between the anthropomorphism score (AS) and the biological reality one (BRS) showing a wrong statement. The heterogeneity of responses proved that all levels of anthropomorphism are covered from mentaphobia to full anthropomorphism. However, the scores participants attributed to animals differ according to the species shown in the video and to human characteristics. Understanding how one can play with these factors can conduct to better relationships with animals as encourage human-robot interactions. Finally, such reflective anthropomorphism can lead to an increase of human empathy and sociality, finally increasing our humanity.
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