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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: I also disagree with Morgan's idea about eliminating cats in general. Like other people, I'm also concerned about removing the predators (feral cats) that you never know if other predators will be replaced on their role and increase preys population. For example, the wolves removal in Yellowstone National park in the U.S. Removing the top predators in the ecosystem disturbed the whole balance of the ecosystem and animals behaviors. Looking past regulation and actions have been done, we can not decide a extreme action so soon before we know what would be the consequences.

    To adjust this problem I think it will work a lots better if the two extreme group: cats colony caretakers and bird conservationists should find a common ground to work together and decide a good and balance solutions to solve the real issues. I believe many cat owners are very willing to participate in studies or research about cats as threat to biodiversity. (http://www.sciencedaily.com/releases/2012/09/120906181643.html)
    A study to monitor own-cats and un-own cats actually already have been done by Jeff Horn in a neighborhood near center Illinois. (http://www.sciencedaily.com/releases/2011/05/110526114531.htm) A research to study and collect data from firsthand and ground data could be more relevant than reading how many birds and endangered species were killed by one of our family member---cats. The interesting found on this study was that house cats rarely go too far from the houses. Their territories were way smaller than un-own cats.

    The other issues I think it also depends various areas, such us, urban, rural, and endemic islands.To consider feral cats as invasive species in a small island is vital because they might really kill large amount of endemic birds and causing threat to endangered species. Solution can be regulating families with cats on the island and ship un-own cats to bigger urban area for adoption. (http://www.sciencedaily.com/releases/2013/02/130201090610.htm)
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      May 7 2013: To build on the idea of feral cats as invasive species on small islands, I found an article that covered a project to eradicate feral cats on the Ascension Island . This island was once home to the frigatebirds that have long been endangered and near to extinction since cats were introduced in the early 19th century. The Royal Society for the Preservation of Birds (RSPB) began a program to remove all feral cats from the island, resulting in the eventual return of nesting frigatebirds to the island. Although I understand the limitations of eradicating cats in larger geographical areas I think it is interesting and worthwhile to look at this case. Perhaps in areas under extreme threat and that are geographically small enough, drastic eradication may be necessary and possible. Additionally it will be helpful to follow if and how bird populations on this island repopulate to better understand the effect of removing feral cats.

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        May 7 2013: Wow Kacie! That article is a fantastic example of how after feral cats are eradicated, we see birds returning to the island. This supports a wonderful compromise where there are still household cats (regulated, but present) and the sharp decrease in feral cat populations. It was also cool to see that they were humane about the whole process and it only took 4 years to declare the island feral cat-free. Again, great find :D

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