The Plight of Birds - Part Two - Cats
    THE EFFECT OF CATS ON WILDLIFE

    Many rehabilitators are frequently approached by people who tell them, somewhat abashedly, that their cats are
    constantly bringing in birds. When it is suggested that here is something that a single individual can do to
    positively mitigate human impact on wildlife, their eyes glaze over. While many cat owners may believe their pet
    cannot possibly have a significant impact just because it hunts, the cumulative devastation of cat attacks on
    wildlife is substantial.

    With many species in danger due to habitat loss, predation by house cats is yet one more hardship we humans
    impose on wild animals already struggling to survive in our human-dominated world.

    Yes, tropical forests are being cleared, wetlands are being destroyed, migratory birds are losing habitat along
    their entire migration route, they are losing insect prey and even their own lives to pesticides... but much of that
    feels beyond our individual, immediate ability to effect significantly. Limiting the toll that cats take on wildlife,
    however, is an action that is immediate and effective on an individual basis.

    The Migratory Bird Treaty Act protects native birds from being killed or kept by people. Any person who willfully
    allows his or her cat to injure or kill migratory birds is, in effect, in violation of this federal law. While this may
    seem like an extreme interpretation, the "sport" hunting of wild animals by our well-fed pet cats is a waste of life
    and a crime against our wildlife, at least ethically, because it is preventable.

         
    Consider the following:

         
          1. In 1987, Peter Churcher and John Lawton asked the owners of cats in a Bedfordshire, England, village to
    keep any 'gifts' brought to them by their cats; owners of 78 house cats participated (all but 1 cat owner in the
    village), with the researchers extrapolating from these findings to estimate that the 5 million house cats in
    England were responsible for killing approximately 70 million animals each year, 20 million of which are birds.
    [PB Churcher and JH Lawton, 1987, "Predation by domestic cats in an English (UK) village. Journal of Zoology.
    (London.) 212:439-455.]

         
          2. A four-year study in rural Wisconsin by Coleman and Temple confirmed the UK findings; 30 cats, radio-
    collared for various periods of time, led researchers to conclude that, in Wisconsin alone, cats may kill 19 million
    songbirds and some 140,000 game birds in a single year. The researchers focused on rural areas, where
    residents averaged more than 4 cats apiece, working out to a density of 57 cats/sq mile. [JS Coleman and SA
    Temple, 1993. "Rural residents' free-ranging domestic cats: a survey. Wildlife Society Bulletin 21: 381-390] In
    urban areas, however, cat populations can be more than 2,000 cats/sq mile. [Marin Conservation League, Sept
    1995 issue of the MCL News, "Is There a Fluffy Killer in Your Home?"] Temple, a professor of wildlife ecology at
    the University of Wisconsin, also stated that house cats are probably the principal predator of birds and small
    mammals in many areas of rural America. Using figures from Wisconsin and Illinois, he found that outdoor cats
    kill 47 million rabbits a year - more than human hunters kill with guns. Temple points out that cats may also be
    the chief threat to some bird populations, especially grassland birds (many of which are in decline already due
    to habitat loss.)

         
          3. In Virginia, Dr. Joseph Mitchell, an ecologist at the University of Richmond, and his colleague, Dr. Ruth
    Beck, conducted a study using their own cats. During the 11 months of their test, their 5 cats killed at least 187
    animals, mostly small mammals. Of special interest to the researchers was the impact on songbirds, which are in
    decline in the state - they conservatively estimate that domestic cats each kill at least 26 birds each year in
    urban areas or 83 in rural areas, representing over 26 million birds in Virginia alone. Mitchell says "The figures
    may be conservative, because the study only counted confirmed kills - not cases in which cats ate their victims
    or left the bodies hidden." [JC Mitchell, 1992. "Free-ranging domestic cat predation on native vertebrates in
    rural and urban Virginia." Virginia Journal of Science, Vol 43 (1B):107-207.]

         
          4. Worldwide, cats may have been involved in the extinction of more bird species than any other cause,
    except habitat destruction. Cats are contributing to the endangerment of populations of birds such as Burrowing
    Owls, Least Terns, Piping Plovers and Loggerhead Shrikes. In Florida, marsh rabbits in Key West have been
    threatened by predation from domestic cats. Cats introduced by people living on the barrier islands of Florida's
    coast have depleted several unique species of mice and woodrats to near extinction. [Humphrey, S.R. and D.B.
    Barbour. 1981. "Status and habitat of three subspecies of Peromyscus polionotus in Florida." Journal of
    Mammalogy 62:840-844. Gore, J.A. and T.L. Schaefer. 1993. "Cats, condominiums and conservation of the
    Santa Rosa beach mouse." Abstracts of Papers Presented, Annual Meeting of the Society for Conservation,
    Tucson, Arizona, June, 1993.]

         
          5. Many humane societies and rehabilitation centers doing education, quote the following for a country-wide
    estimate of the impact of owned cats on birds. Richard Stallcup of the Point Reyes Bird Observatory estimated
    that of the 55 million domestic cats in the US, excluding Hawaii and Alaska, some 10% never go outside, and
    another 10% are too old or slow to catch anything. Of the remaining 44 million, a conservative estimate is that 1
    in 10 cats kills a bird a day - this would yield a daily toll of 4.4 million birds - or 1.6 billion cat-killed birds in the
    US each year. ["Cats take a heavy toll on songbirds / A reversible catastrophe," Observer, Spring/Summer
    1991, 18-29, Point Reyes Bird Observatory; Native Species Network, Vol 1 Issue 1, Fall 1995.] Research has
    shown that rural cats, with more wildlife contact, kill many more, with the result that the feral cat population, most
    of which is rural, has an even more significant impact on the bird population. Alley Cat Allies estimates that there
    are 60 million feral cats in the United States. Combining feral and domestic cat predation, it is estimated that
    more than 3 billion birds are killed annually.

         
          6. Cat predation can also negatively impact our native predators, including raptors (hawks, falcons, and
    owls). A study in Illinois concluded that cats were taking 5.5 million rodents and other vertebrates from a 26,000
    square mile area, effectively depleting the prey base necessary to sustain wintering raptors and other native
    predators. [WG George, 1974. "Domestic cats as predators and factors in winter shortages of raptor prey." The
    Wilson Bulletin 86(4):384-396. O Liberg, 1984. 'Food habits and prey impact by feral and house-based
    domestic cats in a rural area in southern Sweden." Journal of Mammalogy, 65(3): 424-432.]

         
          7. Domestic cats have passed diseases (feline leukemia, distemper, and an immune deficiency disease) to
    wild populations of felines, including the endangered Florida Panther. [Jessup, D.A., K.C. Pettan, L.J.
    Lowenstine and N.C. Pedersen. 1993. "Feline leukemia virus infection and renal spirochetosis in free-ranging
    cougar (Felis concolor)." Journal of Zoo and Wildlife Medicine 24:73-79. Roelke, M.E., D.J. Forester, E.R.
    Jacobson, G.V. Kollias, F.W. Scott, M.C. Barr, J.F. Evermann and E.C. Pirtel. 1993. "Seroprevalence of
    infectious disease agents in free-ranging Florida panthers (Felis concolor coryi)." Journal of Wildlife Diseases
    29:36-49.]

         
    The impact of cats on native wildlife has been the topic of worldwide attention. A 1992 National Wildlife article by
    George Harrison, "Is there a killer in your house?" (National Wildlife 30(6): 10-13), shows that even well-fed cats
    will hunt and discusses the problems of people who want songbirds on their property but who refuse to
    acknowledge the impact of their free-ranging cats. (And add into the equation of the dangers facing an outside
    cat the problem of them being injured or captured by a bird-loving neighbor tired of them hunting the wildlife on
    HIS property.) Sherbrook Shire, near Melbourne, Australia, has imposed a curfew on cats (Australia has
    suffered a severe decline in native mammals and some birds, in large part because of domestic cats) - owners
    whose cats are out at night face a $100 fine. The University of Wisconsin Cooperative Extension office has
    issued a bulletin authored by three biology, conservation, and extension professors, expressing concern over
    the impact of cats on wildlife, making available (free of copyright) in print and over the Internet [John Coleman,
    Stanley Temple, Scott Craven, 1997, "Cats and Wildlife - A Conservation Dilemma,' published by the University
    of Wisconsin Cooperative Extension Service, at http://www.wisc.edu/wildlife/e-pubs.html

    Animal intake data from many wildlife rehabilitation centers across the U.S. corroborate the toll of cat predation
    that the above findings document. Overwhelmingly, cat predation (including cat attack cases and animals
    orphaned by cats) is the single largest reason for admission to many wildlife centers, over car and window
    collisions, oil spills, pesticides, tree felling, and all else. Unfortunately, the prognosis for recovery of cat attack
    victims is poor. Typically less than 10-20% survive. Necropsies of cat attack victims admitted to wildlife
    rehabilitation centers reveal massive internal hemorrhaging and soft tissue damage from crushing even when
    external damage appears minor. Also, even small puncture wounds expose the victim to over 60 types of
    bacteria in cat saliva.

         
    Perhaps the answers to some commonly asked questions about cats and wildlife will provide some ideas and
    solutions.

         
    Q. Isn't hunting by cats natural?
    A. While it may be "instinctive" for them to hunt, house cats are not native to North America and they cause
    imbalances in the ecology of an area by killing so many native wild animals. By being at large at any time, day or
    night, they have an advantage over native wild predators that tend to be either nocturnal or diurnal. Because
    their population numbers are artificially large due to being kept as pets, cats are also far more common than the
    balance of nature would allow for native predator species, such as fox or bobcat. Predators are supposed to be
    rare, not abundant, in nature. Normally, the population of prey species (i.e., the amount of available food)
    determines the population of predators. With pets, who are not dependent on the animals they catch for food,
    their numbers are dependent only on the area's human population.

         
    Q. Will putting a bell on my cat's collar help?
    A. A bell is not normally a sound birds would associate with danger. Although neighborhood adult birds may
    learn that the bell sound of the local cat represents danger (assuming they escape initially), young birds and
    less common birds that are migrating through your yard will still be at risk. Also, many cats are bright enough to
    figure out how to stalk silently even with a bell. Some people have found that a 'rhinestone' collar that reflects
    light, as well as two bells or more, may help some - but there is no solution better than keeping the cat under
    your control at all times.

         
    Q. Aren't well-fed cats less of a threat to wildlife?
    A. Because hunting is instinctive for cats, even well-fed cats still hunt. "Studies of housecats suggest that
    hunger and hunting are controlled by different parts of a cat's brain. Hunting is a form of amusement for the cat,
    much as a dog enjoys chasing a stick." (Guy Hodge, Humane Society of the United States, "Mitigating the Impact
    of Free-Ranging Cats on Wildlife," Proceedings of the 1995 International Wildlife Rehabilitation Council
    Conference, 1996.) A well-fed pet cat is apt to be more fit, and thus a more successful hunter, than a feral cat
    that hunts to survive. By the same token, feral cat 'colonies' that are fed only amplifies the devastation of having
    such a concentration of small predators.

         
    Q. My cat just helps keep my yard free of mice or other small rodents. How can this be harmful?
    A. Particularly in suburban/rural situations, the prey base for hawks and owls may be depleted, and this may
    have far-reaching consequences. A study in Maryland found that Cooper's Hawks, which depend heavily on
    chipmunks to feed their young during the nesting season, were forced to prey more on songbirds if chipmunks
    were eradicated. (Mosher, J. 1989. Status reports: accipiters. In Proceedings of Northeast Raptor Mgmt.
    Symposium. Washington D.C.: National Wildlife Federation.) Not only did this put additional pressure on the
    songbird population, but the increased hunting time and difficulty caused the hawks' nestling survival rates to
    suffer. Similar population effects would arise from limiting the mouse population for the local screech owl or
    kestrel pair.

         
    Q. When are birds more at risk?
    A. At any time during the nesting season (March through October), both adults, which are harried with nesting
    duties, try to defend their young and are at risk. Often the female bird is taken while brooding her young on the
    nest, in which case the nestlings will die of cold or starve to death, if they are not killed as well. Young birds still
    unable to fly well are at great risk. All birds are also at risk at night, at any time of the year. Diurnal birds are
    night blind and if surprised while asleep are virtually helpless to escape a cat attack. In addition, birds may be
    vulnerable at birdbaths and/or feeders, if there is low vegetation close by in which cats can hide. Birds are most
    active in the early morning and at the very least, cats should thus be confined for the first few hours after dawn
    and at night.

         
    Q. Is there any way to protect birds from neighborhood cats at my feeder or birdbath?
    A. Provide escape cover with brush piles and thorny shrubbery for the birds to fly into, but keep the ground
    clear under the feeder or near the bath so that cats cannot hide within pouncing distance. In extreme situations,
    erecting a circle of 2' tall chicken wire around a feeding station may be effective.

         
    Q. I feel terrible that my cat hunts, but he is used to roaming outdoors and drives me crazy to go out. Can I train
    him to stay indoors?
    A. It may be hard to break an adult cat of the urge to roam outdoors, but let your cat out as infrequently as
    possible, keep him confined to your yard under your observation, and gradually increase his stays indoors.
    Having your cat spayed or neutered will help as well. It's best not to let a cat roam outdoors to start with. A kitten
    which is not allowed to roam will not expect to do so as an adult, and you will gain a loving pet for many more
    years. A cat that lives indoors has a long life expectancy. Cats that roam do not. The outdoors is dangerous for
    cats, too! And your vet bills will be much lower without the risks of exposing your cat to cars, cat fights and
    diseases, dogs, or larger predators.

         
    Q. How else can I help?
    A. Defend your backyard sanctuary against marauding cats. Fencing a yard helps. Repel intruding cats with
    spray from a garden hose. Speak up in support of laws that prohibit cats from running at large on others'
    property.

         
    All native birds (no matter how common!) are protected by state and/or federal law, as are many mammals.
    Certainly they deserve the additional, so easily ensured protection from domestic cats. In Oregon, a dog
    chasing livestock can be put to death; this is not so much out of consideration for the livestock as it is the fact
    that such animals are is deemed 'personal property' and the owner's rights are thus imperiled by harm to them.
    Surely our wildlife merits at least an equivalent protection - not as personal property but as a shared resource
    that both provides benefits for all of us.

         
    For further references, see A bibliography of feral, stray, and free-roaming domestic cats in relation to wildlife
    conservation, compiled by Ronald Jurek, April 1994, California Dept of Fish & Game, Nongame Bird and
    Mammal Program Report No. 94-5.

         
    Thanks to Louise Shimmel of Cascades Raptor Center in Oregon for use of this article. Some portions of this
    article adapted from "Cat Facts," a bulletin of the Ohio Wildlife Rehabilitators Association and "Cats and Wildlife
    - A Conservation Dilemma,' published by the University of Wisconsin Cooperative Extension Service, at
    http://www.wisc.edu/wildlife/e-pubs.html

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