Pussy Cat, Pussy cat, what have you killed?

In the early eighties, our parents rescued two abandoned stray kittens from the road, which started a long line of cat dynasty in our house and the neighbourhood. Our house gained the reputation of being a sanctuary for abandoned cats, that we had people stealthily abandoning their cats outside our house gates. At one point, we had about 12 cats in the house. We loved these animals dearly; but despite being fed adequately, we were horrified to note that they killed squirrels, birds, bats, bandicoots, rats and mice. We lamented their notorious habit of murdering birds and squirrels, particularly as we fed them too, and could never comprehend how our adorable pets could turn into merciless masochistic killers, particularly as they never ate their kill. The carcass was presented for us to see almost very time.  I remember one time when my mother was inconsolable, when a cat killed one of ‘her’ doves that she had grown so attached to. Our repeated efforts to teach the cats 'good behaviour' was not fruitful.  

The  results presented in recent paper in Nature Communications by Loss and his colleagues on the 'The impact of free-ranging domestic cats on wildlife of the United States' was not a surprise in one respect ,as we all know that cats kill birds and smaller mammals. However, what was surprising was the magnitude of the effects. Domestic cats have been introduced globally by man and are linked to the extinction of several animals on islands, whilst their effect on other places had not been scientifically estimated. In their study, the authors estimate that in the US, domestic cats alone kill 1.4-3.7 billion birds and 6.9-20.7 billion mammals every year, and that cats that are not owned (feral cats) as opposed to owned pets, cause the majority of the killing. What is different about the study when compared to previous ones, is the actual quantification the authors conducted, which suggest that cats cause significant and substantial wildlife mortality than previously thought. Interestingly, these cute and cuddly creatures which are the most popular pets in the world are the primary and greatest source of anthropogenic (caused by humans- in this case indirectly) mortality for US birds and mammals. This makes me wonder, whether their new found notoriety would affect their popularity as pets. For some reason, I doubt it.

References:

1. http://www.tau.ac.il/lifesci/zoology/members/yom-tov/inbal/cats.pdf
2. Loss, S., Will, T., & Marra, P. (2013). The impact of free-ranging domestic cats on wildlife of the United States Nature Communications, 4 DOI: 10.1038/ncomms2380