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Jon Cox

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Cats pose a serious threat to biodiversity: Why do we accept it? What should be done?

According to the ASPCA, there are around 90 million owned domestic cats (Felis catus) in the U.S., and taking into account strays and feral cats, the total number is estimated to be as high as 160 million (1). Loss et al. (2013) estimates that cats roaming outdoors kill 1.4-­3.7 BILLION birds and 6.9­-20.7 BILLION mammals in the U.S. annually (2). Reptiles and amphibians such as snakes, lizards, frogs, etc., are also frequently killed by cats.

Cats are even more popular New Zealand, where they are contributing to declines of endemic birds such as the critically endangered kakapo (3), which have evolved in the absence of predators. Businessman/philanthropist Gareth Morgan is trying to gather support for legislation that would aggressively deal with stray and feral cats and potentially eliminate cats from New Zealand to take pressure off of threatened species (4 & 5). With Morgan’s plan, in addition to regulation that would reduce cat populations and increase owner accountability, residents would be encouraged to not replace their cats. As of now the majority of New Zealanders surveyed are in opposition to Morgan’s initiative.

Would a proposition like Morgan’s meet similar resistance in the U.S.? Probably, but is he on the right track? Would you personally support something like it for your state or country? Why or why not is it a good idea? Is this type of legislation necessary to curb the problem and protect wildlife? If you disagree, what are some alternatives? Will the aesthetics and familiarity of cats keep them off limits to such ideas in the opinions of the general public?

1. http://www.aspca.org/about-us/faq/pet-statistics.aspx
2. http://www.abcbirds.org/abcprograms/policy/cats/pdf/Loss_et_al_2013.pdf
3. http://www.avianweb.com/kakapo.html
4. http://www.npr.org/blogs/thetwo-way/2013/01/24/170191917/new-zealand-environmentalist-wants-to-eliminate-cats-to-save-birds
5. http://www.livescience.com/26525-cat-eradication-new-zealand-save-birds.html


Closing Statement from Jon Cox

Thanks to everyone who contributed to a thought provoking discussion!

I think we can all agree that we need to be responsible with our pets! For the sake of ecological and human health. And pet owners must realize that their carelessness is costly. Plans to completely eliminate cats from areas where they are very popular are pretty far fetched, but stricter regulation is a must, and domestic cats do NOT belong in the wild, period. Feral cats need to be seen and dealt with just as any other invasive species. However, extreme caution is necessary in any attempt to remove them where they have become established as a keystone species.

Check out Australian cat laws for a look at the legislation adopted by a people who cherish their native wildlife and do not want to see it be destroyed by invasives.

And lastly, we must keep in mind that invasive species are just one way in which we threaten biodiversity. Overexploitation and especially habitat loss pose even greater threats to species survival.

Thanks again!


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    May 7 2013: In order to reduce the threats of biodiversity caused by cat, there are several ways could be done. It is people's right to keep cats as pets and asking people not to keep cats is not a good idea. But we can ask them to hold their cats and do not let them hang out anywhere. If under owner's supervision and they also eat full everyday, they won't attack birds or other animals.

    Furthermore, the feral and stray cats are the main cause of extinction of some birds or species. But cats is also a component of food web, which just as a predator of birds to prevent birds numbers too large to harm plants. But for the endangered species, they can easy to be extincted. So they need to be protected from cats. However, it is not necessary to eliminate cats. You can just prevent cats from that endangered species habitat by putting something that cats are afraid to. For instance, like I studied in conservation biology, to protect habitats from elephants, just introduce some bees because elephants do not like bees. So I think the alternative strategy is to make cats away from endangered species habitats.
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      May 7 2013: Good point about fear. The first thing that comes to mind is that cats are afraid of water... Maybe cat owners should be required to purchase a motion-censored squirt gun/sprinkler that they then place near bird feeders? Or owners could have the option of writing into, say, the Audubon Society, who sends them one free of charge?

      I have also heard the suggestion that owners can scatter citrus peels (oranges and lemons), or spray a mixture of citrus oil and water. Apparently, cats hate it.
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      Mario R

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      May 7 2013: What about leash laws? I think that leashing up those cats would do wonders to restrain them from attacking the local fauna. This would require owners to closely regulate their pets instead of simply letting them frolic about unattended.

      I also like the idea that a few people have discussed of obligatory micro chipping. This way cat owners can be aware of their animals' whereabouts and can closely monitor them.
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        May 7 2013: I agree! These cats need leashes! When I'm out there walking my boys on their leashes they always get really jealous when they see those cats strutting around free. And my dogs don't like it either! LOL!

        God Bless

        -Todd C.
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      May 7 2013: Yes, I agree with the idea of fear to drive cats away from endangered species habitat. House cats can be seen as invasive species to a wildlife-friendly yard. Even when cats are full, their instinct can drive them to hunt and kill available prey, such as birds, insects, insects and small amphibians. However, there is no reason we should eliminate them since we cannot protect other endangered species under the cost of threatening existing species. By using the fear of cat, people can use water to deter cat. Just as Becca pointed out, people can use a gentle spray of water from a water pistol. This is an inexpensive way to vacate from wildlife-friendly habitat. Other ways such as motion-activated sprinklers at entrance points, cat-proof fencing, and thorny brambles under feeders may also work to prevent house cats from other species’ habitat. Most importantly, I think people should keep their cats indoors most of the time and when they are out should be under surveillance. This method is mutually beneficial for cats and birds outside. One study also pointed out an alternative method by using ultrasound deterrents. This method can eliminate the use of physical barriers and the ultrasound should be specifically for cat. The device use motion/heat detectors for cat. However, this method is a little expensive but work out efficiently with time. Cats are learning to avoid gardens or habitat with these active devices.
      You can check out the ultrasound study here:
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        May 7 2013: I like your idea about deter cats by water and ultrasound. And considering the cost is necessary.

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