The Domestic Cat: Felis catus

Invasive Species of Concern in MarylandInvader of the Month: Feral Cats

Brian Clark, University of Maryland Extension

ANNAPOLIS, MD (April 15, 2010)

Feral cats (Felis catus) are a perfect invasive species. They are non-native to North America, have a high reproductive rate, relatively low mortality, and high dispersion rates. They also have the ability to be cute and cuddly, a perfect shield from those that wish to do them harm.Cats are the purrfect hunter, a mix of power, stealth, and speed. Domesticated cats are simply scaled down versions of their larger cousins. As a domesticated species, they have put their hunting capabilities to good use, protecting our health and property from rodents that would destroy what we have. However, when these cats are released into the environment on a permanent basis, they can disrupt the balance of an already fragile ecosystem. When cats are first released into the environment, they are generally referred to as strays, and can be reincorporated into domestication with little difficulty. As the generational gap increases between domestic-ated and non-domesticated, adult feral cats are less likely to be re-domesticated.However, small cats are not part of the native food web in North America and can wreak havoc on an ecosystem. It is believed that between 50 and 100 million feral cats roam the United States, with 70 million being a conservative consensus among experts. Small mammals such as mice and moles make up a majority of their prey. Even with their ability to fly, birds, especially nestlings or fledglings, make up approximately 20% of a feral cat’s prey. During a study of feral cats in Wisconsin, a single cat averaged 3.1 animal kills each day. If each cat kills one animal, each day, up to 36.5 billion animals could be killed by feral cats each year. Feral cats can take a toll on native wildlife, decimating populations already under stress due to habitat shrinkage. Their hunting abilities are used on rodents, birds, insects, reptiles, amphibians, and even fish. The number and size of prey that a small cat can bring down will amaze you. Even full grown rabbits can be killed. Supplemental feeding of feral cats is not an answer. Even well-fed feral cats will capture and kill, but not always eat, their prey.Many of the feral cat’s other nuisance habits can be attributed to mating behaviors. These behaviors include noise from fighting and mating, and the smell from their pheromone-

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The Domestic Cat: Felis catus

laced urine. When they come into contact with roaming domesticated cats, there is also the chance for the spread of diseases like rabies and parasites, such as fleas.For those who love all animals, this presents a huge problem. Do you control the feral cat or not? Failure to control a highly predatory, non-native species that has proven to kill many of the small native species we enjoy is a necessity to preserve the overall balance of an ecosystem. But to kill a cat, an animal that so many people love, is a political nightmare for farmers and environmentalists.Control can be a tricky issue. The first step is to prevent the release of new cats into the environment. If you are unable to care for your cat, adoption is preferred. An animal shelter is the next best and often legally the only other option. The next step is dealing with existing populations of feral cats. Many people are protective of feral cat colonies. There are hundreds of organizations out there that offer education to the public and protection to the cats. The two most common control measures are trap-euthanize or trap-neuter-return (TNR). Euthanizing feral cats is a method used primarily by government institutions, as it provides control with the lowest cost. TNR is the procedure most recommended by feral cat advocates.Then there is the cycle of life. Feral cats themselves are hunted. Large hawks and owls will fly off with the smaller individuals. Coyotes will often kill cats which compete for their food resources. The reemergence of coyotes into Maryland should prove interesting to examine over time.Love your pet. Take care of the native environment. Spay or neuter. Keep your cats indoors.For more information about this and other Invasive Species of Concern, visit www.mdinvasivesp.orgSource: Clark, Brian. Invader of the Month: Feral Cats. (Maryland Invasive Species Council, USDA APHIS PPQ Cooperative

Agricultural Pest Survey, April 15, 2010). Online at http://mdinvasivesp.org/archived_invaders/archived_invaders_2010_04.html

Table 1 Source:Hildreth, A.M., et al. 2010. Feral Cats and Their Management. University of Nebraska, Lincoln Extension. Online at

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What are feral cats? And what do we call cats that are pets? What about pet cats that can go outdoors?Use the chart at right to see the differences between indoor cats, limited range cats, free-range cats, and feral

The Domestic Cat: Felis catus

http://www.ianrpubs.unl.edu/epublic/live/ec1781/build/ec1781.pdf

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The Domestic Cat: Felis catus

Geographic Range The domestic cat (Felis catus) evolved from the domestication of an ancestral wild species (the African wild cat, Felis silvestris lybica) about 3,000 years ago. In the 1700’s and 1800’s, ships carried cats to control rat infestations, and this was a major factor in early introduc-tion of an invasive species. Today, humans bring cats as pets, and may leave the cats behind, or kittens may disperse.

Cat BiologyDomestic and feral cats are distributed across the United States, and are well adapted to living in both urban and rural areas, in a wide variety of settings (for example, in houses, under bridges, within forests, along creeks, and in sewers. They may weigh from 3 to 8 pounds or more, and are from 22 to 36 inches long. (Male cats are usually larger and heavier than female cats). The average life of a feral cat is 2 to 5 years; cats that are owned by people have a life expectancy of 15 years. A female cat reaches reproductive maturity between 7 to 12 months of age. Feral cats can produce up to 3 litters each year, and litters generally include 2-10 kittens. Mating and reproduction season for cats is spring and summer; the gestational period is 65 days. Female cats care for their kittens in a den for about seven months, and then the family unit breaks up and the young cats are on their own. Ecological ImpactBiologists at the University of Georgia found that outdoor cats that killed did so once every 17 hours. The researchers attached small video cameras to 60 outdoor domestic cats in the city of Athens, Ga., and recorded their outdoor activities during all four seasons.

In the US, cats are one of the top ‘super-predators’ of wildlife, and their most significant impact is on bird populations. On a global scale, cats have caused the extinction of at least 33 bird species from around the world, and kill about 480 million birds per year. Approximately one-third of the birds killed each year are killed by domestic cats (pets),

not feral cats.

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Cats prey on wildlife.Photo by Stephen M. Vantassel

http://www.ianrpubs.unl.edu/epublic/live/ec1781/build/ec1781.pdf

The Humane Society of the US estimates that

one pair of breeding cats and their offspring can produce

400,000 cats in seven years! (Assuming ideal conditions and

none die).Source: Loss, S.R. et al. 2013. The impact of free

ranging cats on wildlife of the United States: Nature Communications.

The Domestic Cat: Felis catus

Scientists from the Smithsonian Conservation Biology Institute and the U.S. Fish and Wildlife Service estimate that domestic cats in the United States, including pets that spend part of the day outdoors and strays and feral cats, kill 1.4±3.7 billion wild birds and 6.9±20.7 billion mammals every year (most of the mammals are native wild mammals like shrews, chipmunks and voles, instead of introduced pests like the Norway rat), plus numerous reptiles. In California areas with feral cats, housemice (an invasive species) were more abundant (more

likely to survive) than native rodents. Feral cats also pose a threat to poultry producers (chicken farms),and even to other cats. Recent studies estimate that free-roaming pets account for only about 29% of the birds and 11% of the mammals killed by domestic cats each year, and the real problem arises over how to manage the 80 million or so stray or feral cats that commit the bulk of the wildlife slaughter. Economic and Other ImpactsEcologists estimate that predation of birds by cats has an economic impact of over $17 billion per year in the United States. Free-roaming cats account for the most cases of human rabies exposure among domestic animals, and are the source for at least one-third of rabies post-exposure treatments in the US: this is another significant economic impact.Humane societies estimate that the cost imposed on U.S. taxpayers each year to impound, shelter, euthanize, and dispose of homeless animals (including cats and other animals) is $2 billion.Looking at the issue from humane societies provides a more personal perspective. Each day, about 70,000 puppies and kittens are born in the United States.  (In contrast, 10,000 humans are born in the United States each day; there will never be enough homes for animals with animal birth rates so high). In 2012, six to eight million cats and dogs were taken to animal shelters in the US, and 2.8 million were euthanized.Sources: Fenwick, G. 2013. House cats: The destructive invasive species purring on your lap: Baltimore Sun, February 25, 2013.

Online at http://articles.baltimoresun.com/2013-02-25/news/bs-ed-cats-20130225_1_outdoor-cats-house-cats-rabies-exposure

Hildreth, A.M., et al. 2010. Feral Cats and Their Management. University of Nebraska, Lincoln Extension. Online at http://www.ianrpubs.unl.edu/epublic/live/ec1781/build/ec1781.pdf

Loss, S.R. et al. 2013. The impact of free ranging cats on wildlife of the United States: Nature Communications. Online at http://www.nature.com/ncomms/journal/v4/n1/full/ncomms2380.html

Felis catus, mammal, in Global Invasive Species Database. (Invasive Species Specialist Group of the IUCN Species Survival Commission). Online at (GISP)

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More birds and mammals die at the mouths of cats

than from automobile strikes, pesticides and poisons, collisions with

skyscrapers and windmills, and other

causes.Source: Loss, S.R. et al. 2013. The impact

of free ranging cats on wildlife of the United States: Nature Communications.

The Domestic Cat: Felis catus The Humane Society of the United States. 2012. Online at http://www.humanesociety.org/issues/pet_overpopulation/facts/pet_ownership_statistics.html

Sources of both graphs: Woods, M. et al. 2013. Domestic Cat Predation on Wildlife: The Mammal Society. Online at

http://www.mammal.org.uk/sites/default/files/Domestic%20Cat%20Predation%20on%20Wildlife.pdf

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Numbers of mammals, birds, and reptiles brought home by cats that did not wear bells (white columns) and that did wear bells (black columns).

Reptiles

Reptiles

Numbers of mammals, birds, and reptiles brought home by cats that were not allowed outdoors at nights (white columns) and that were allowed out at nights (black columns).

Numbers of mammals, birds, and reptiles brought home by cats that did not wear bells (white columns) and that did wear bells (black columns).

Reptiles

The Domestic Cat: Felis catus

What is the best control plan?Since cats are revered as pets in our society, this raises the moral dilemma of how to handle them when they have become a threat to native wildlife. Animal rights activists argue that many control methods, especially euthanization of feral or domesticated cats, are unethical. Some animal welfare groups feed feral cats, while PETA recommends trapping, neutering, and adopting feral cats. Wildlife organizations argue that cat predation of wildlife is serious, and that humans sheltering and feeding cats is directly responsible for the cat population reaching a density one hundred times greater than the populations of their native counterparts. Public health specialists argue that feral cats are responsible for the transmission of serious diseases. Humane societies work hard to educate the public about the impact of an exploding cat population, but

the problem remains.Obviously there are two quite different situations for management of the species, depending on the status of the cat: one is where a cat is a domesticated household pet, and the other is when a cat has gone wild or feral and has no owner to protect and feed it. Both situations involve different stakeholders, and different solutions. To further complicate the issue, in many states, since feral cats are not classified as wildlife, responsibility for management of the cat populations is unclear.

Different communities, states, and nations have approached the cat issue with a variety of species management tactics, from habitat modification, fencing, repellants, trapping, fertility control, and finding foster homes, to euthanization and hunting.

Sources: Ecological Impacts of Feral Cats. 2011. The Wildlife Society. Online at

http://joomla.wildlife.org/documents/cats_ecological_impacts.pdf Hildreth, A.M., et al. 2010. Feral Cats and Their Management. University of Nebraska, Lincoln Extension. Online at

http://www.ianrpubs.unl.edu/epublic/live/ec1781/build/ec1781.pdf

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The BP Deepwater Horizon oil spill, widely considered to be the worst

environmental disaster in the history of the United States,

resulted in the deaths of over 7,000 birds:

A 2009 study estimated the number of birds killed by cats

every year in the United States at one billion, conservatively.

The Domestic Cat: Felis catus

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The Domestic Cat: Felis catus

On the prowl: In suburban backyards and rural fields, free-roaming cats are pouncing on songbird populations.John S. Coleman and Stanley A. Temple Some days, you need a bit of imagination to view a house cat as a predator. Sitting in a sunny window, or curled up on a bed, most tabbies hardly seem to have the energy to attack their food dish. But cats are definitely hunters, and there are plenty of them in town, in barns and free-ranging in fields to put the bite on a variety of birds and other wildlife.Cat populations are tough to estimate accurately. U.S. Census data track cats that people claim to own as pets, and the numbers are impressive. From 1970 to 1990, the number of urban and rural cats counted in the census rose from 30 million to 60 million. Nationwide, approximately 30% of households ‘own’ cats. In rural areas, where free-roaming cats often are not regarded as pets, and not recorded by the census, as many as 60% of households keep cats on their property. Nationwide, there must be at least 100 million cats.Wild at heartAlthough cats make affectionate pets, their skills and behaviors as predators remain un-changed from those of their ancestors, and they hunt as effectively as their wild forebears.However, house cats differ from wild predators in several important ways: First, people protect cats from disease, predation and competition. Modern veterinary practices, from vaccination to bone setting, substantially extend a pet cat's lifespan. Second, domestic cats adapt well to human domiciles. Unlike native predators, cat densities are not limited by space or the availability of prey. Even barn cats have significantly better shelter, food and water supplies than bobcats, foxes and coyotes. The cat's range extends every time people build new homes and outside shelters. Third, although most people supply their cats with food, research shows feeding does not suppress the cat's instinct to hunt and kill.These factors combine to make free-ranging cats a potent predatory force, especially in rural areas. We've estimated that in some parts of rural Wisconsin, cat densities reach 114 animals per square mile – much higher than all mid-sized native predators. Given ample food supplies and high reproductive rates, cat densities can exceed nine animals per acre.Rural cats have access to many animals and have the greatest impact. Small mammals like mice and voles make up about 70 percent of their diets, birds constitute about 20, and a mix of other animals constitute the remaining 10%. Research in Wisconsin suggests that free-ranging rural cats may be killing 219 million birds in the state; many are native song-birds whose populations are

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The Domestic Cat: Felis catus

already stressed by factors including development, habitat destruction and pesticide pollution. Many of these birds are ground-nesting birds, like meadowlarks and sparrows, or birds that often feed on the ground, like robins.Cat predation affects wildlife dynamics in other ways. Domestic cats eat many of the same animals that native predators eat. Studies show that large numbers of cats reduce available prey for predators, such as hawks and weasels.Free-ranging cats may also transmit diseases to wild animals. Domestic cats have spread feline leukemia virus to mountain lions, and may recently have infected the endangered Florida Panther with feline distemper (feline panleucopenia). Unvaccinated cats can also transmit rabies and toxoplasmosis to people. Pregnant women are now routinely advised to avoid contact with cats and litter boxes to minimize the risk of infection.Suggestions for keeping cats in check1. If you are going to keep cats and you don't intend to breed them, get them

neutered at about six months of age. 2. Don't dispose of unwanted cats by releasing them in rural areas. 3. If possible and practical, keep your cat indoors. 4. Research shows bells on cat collars are mostly ineffective in preventing

predation. 5. Declawing may reduce hunting success, but declawed cats are still effective

predators.6. Locate bird feeders in sites that don't provide cover for cats. 7. Support community efforts to license and neuter domestic cats. Estimating how many birds are killed by cats We estimate 1.4-2 million free-ranging cats in rural Wisconsin, and 23% of their

diet consists of birds. Other studies indicate 20-30% of free-ranging cat kills are birds.

The number of animals killed by an individual cat varies greatly. One rural cat was recorded to have killed 1,690 animals in an 18-month period. On an annual basis, studies record low estimates of 14 animals per free-ranging urban cat to at least one animal per day for rural cats. Other studies reported 28 kills per year for urban cats, and 91 kills per year for rural cats.

Here are our best guesses at low, intermediate, and high estimates of the number of birds killed annually by rural cats in Wisconsin, based on the formula*:

(number of rural cats) x (number of kills/cat/year) x (% of kills that are birds).

Low value:(lowest population estimate) x (twice kill rate by urban cats) x (low percentage of kills that are birds) 1.4 million cats x 28 x 20% = 7.8 million birds killed by rural catsIntermediate value: 

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The Domestic Cat: Felis catus

(mean population estimate) x (intermediate kill rate) x (higher percentage of kills that are birds)1.7 million cats x 91 x 25% = 38.7 million birds killed by rural catsHigh value: (highest population estimate) x (highest kill rate) x (highest percentage of kills that are birds) 2 million cats x 365 x 30% = 219 million birds killed by rural cats

*Note: these estimates do not include predation by urban cats.

Adapted from: Coleman, J.S. and Temple, S.A. 1996. On the prowl: In suburban backyards and rural fields, free-roaming cats are

pouncing on songbird populations. Wisconsin Natural Resources. Online at http://dnr.wi.gov/wnrmag/html/stories/1996/dec96/cats.htm

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The Domestic Cat: Felis catus

Harmful Parasites In Cat Poop Are WidespreadANNA HAENSCHJuly 09, 2013 5:07 PM ET

Playgrounds and sandboxes are popular hangouts for free-roaming cats. What they leave behind may not be so popular with humans.

That cat poop can pose a health risk to humans no longer surprises us. Some cats carry a parasite called  Toxoplasma gondii.  Infected cats shed embryonic T. gondii, called oocysts, in their feces.These oocysts are easily transmitted to humans, and researchers have explored their possible link to various mental health

problems, including schizophrenia. More recently, studies of school-age children show a correlation between testing positive for T. gondii and having difficulty in school.The parasites can cause more acute health problems in newborns and people with weak immune systems, as the Centers for Disease Control and Prevention points out. A report published in Trends in Parasitology explores how substantial a public health threat the parasite poses in the United States. One thing's pretty clear: There are a lot of oocysts out there.Research psychiatrist Dr. E. Fuller Torrey and pediatric infectious disease specialist Dr. Robert Yolken, who have spent years investigating the role that animals play in the spread of infectious diseases, co-authored the roundup. Shots spoke with Torrey, who says there are four factors that he believes makes this a valid health concern: The cat population is growing. Every day about 1 million cats in the U.S. are actively pooping out as many as

50 millionoocysts apiece. The oocycts are hard to kill. There is a well-documented correlation between mental illness and testing

positive for T. gondii antibodies.

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Alan Turkus/Flickr

The Domestic Cat: Felis catus

"This is a public health problem that bears more scrutiny," Torrey says. "We're walking a tight line between alarming people and failing to point out obvious health problems that need to be paid attention to."Correlation isn't the same as causation, however, particularly when it comes to the area of mental health. "The association has been discussed, but it has not been completely accepted by everyone," Dr. William Schaffner, chairman of the department of preventive medicine at Vanderbilt University, told NBC News. "If people were convinced of that, we would have acted on it."Sneaky Parasite Attracts Rats to CatsKatie Lisnik, who is the director of Cat Protection and Policy at the Humane Society, says there are 86 million cats that are household pets in the United States, and another 20 million to 80 million free-roaming cats. The bulk of oocysts are getting dropped in the very places where humans are most active. "Feral cats tend to be where the people are, and it makes sense," Lisnik says. "They want to be around us, and we're their source of food." The presence of large numbers of oocysts on playgrounds and in sandboxes, where kids stick their hands in their mouths every couple of minutes, bears particular attention, Torrey says. "If you have a sandbox that isn't covered, get rid of the sand and cover it when kids aren't playing," he says.He also has advice for green thumbs. "Studies have shown that you can have almost 100 oocysts under your fingernails after gardening. So always wash your hands after gardening, and wash vegetables before eating them," he says.In case you're afraid of what this means for your own pet, Torrey says, "strictly indoor cats really shouldn't be a problem. The chance of them becoming infected is very low."Torrey also says that while there has been a drastic increase in the number of feral cats, there has been a decrease in the number of recorded cases of T. gondii infection. The public, he says, is more aware of the dangers of eating improperly stored meat, a source of infections.But Torrey also points out that T. gondii can sit dormant in the body for 20 years, so it may actually take a few decades to see the epidemiological effects on humans.

Source:Haensch, A. 2013. Harmful Parasites in Cat Poop are Widespread. National Public Radio. Online at http://www.npr.org/blogs/health/2013/07/05/199041322/harmful-parasites-in-cat-poop-are-widespread

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