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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 8 2013: While the chip suggestion for house cats seems like a good idea, the suggestion to eradiacte cats (stray or not) sounds like an unrealistic solution to me (maybe because Morgan's suggestion reminded me a bit of Mao's "Four Pests Campaign", because it badly effected animal relations and Agriculture. Even though the situations for the two are different, I couldn't help but remember that). Besides, there would probably be some sort of consequence from killing them, that we may find out the hard way if we even try. Maybe, to help balance out the negative effects, we could somehow come up with a way to monitor how far they can go? the only problem with this is that it may be pretty costly, and depending on the pet owner, they may not be completely up for that.
    • May 8 2013: Island ecosystems do not equate to continental ecosystems. The only change that happened on my own lands after destroying every last cat of hundreds, is that the native predators were more than happy to move back in and keep the balance of nature in balance -- as it was for thousands and thousands of years until demented cat-lickers dumped their cats on the lands. While the cats were here I actually had a rodent problem show-up, that thankfully disappeared after every last cat was shot dead and buried. (Google for: Parasite hijacks the mind of its host; and you'll get to learn how cats' Toxoplasma gondii parasite actually attracts any rodents they infect with it, right to the cats, and into your homes.)

      If you depend on cats as rodent control, all you end up with is a happy predator-prey balance of nothing but cats and rodents on your lands. The cats having effectively displaced or destroyed all the other native species of animals. And cats will NEVER get rid of rodents. I don't know of too many cats that were designed by selective-breeding to slither into rodent burrows and destroy them where they happily breed -- to keep the cats entertained into perpetuity -- after those rodent litters leave their burrows. But native snakes and other native predators of rodents can and do control rodents -- right at their source. Cats are the absolute worst option for rodent control. Only a total idiot would think cats had any long-term effect to keep rodents in check.
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      Jon Cox

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      May 8 2013: Hi Ana,

      Yeah there would almost certainly be some unforeseen consequences of eradicating cats from a place like New Zealand which suffers from compounded effects of many invasive species. Humans have altered the natural environment so much that at this point any plan to remove an established invasive species would require careful consideration and implementation to prevent potential disastrous results.

      A good example of invasive species removal backfiring horribly is what has happened on Macquarie Island off Australia in the last few decades. It is a ridiculous story. Basically, rabbits and cats were both introduced to the island a hundred or so years ago. Both threatened native sea bird species in their own way.The rabbit population was getting out of control, so in the 60's a deadly virus was released in order to cull the rabbit population. It worked great, but with less rabbits around the cats chose seabirds to be their new favorite food source. Cats were seen as a serious threat to these birds so in the 80's a plan was put into motion to totally wipe out the cats on the island. Well they succeeded in doing this in 2000, but guess what happened afterward? The rabbit population exploded again and vegetation loss is extreme and now exotic plants are moving in to fill in the gaps... The present situation is similar to what it was before any conservation efforts. Possibly worse.


      Scientific article on the situation: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2664.2008.01601.x/full

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