Every six months or so we see a group of articles on the internet from different news sites that are based on the same, new scientific study about the predation of the domestic cat on birds and other animals. Birds are often highlighted. We expect scientists to be unbiased and objective but often they aren’t. I remember one who was caught being biased in favor of the bird.
Some people believe that people who let their cats outside are placing a higher value on the life of a cat than a bird as they let their cat kill birds. Others prefer the lives of birds over cats and present biased statistics to support their arguments that cats need to be dealt with inhumanely. Neither is correct. It is just nature taking its course. We are responsible. We kill far more birds than cats do. We do it through the destruction of their habitat. Of course we are often blind to that. And humans quite clearly believe that their lives are more valuable than another other. I don’t think we have a right to make judgments about the value of other animals.
Note: Comments from the violent “Woodsman” will not be published so please don’t bother.
A recent study by the University of Georgia and National Geographic allows me to revisit this debate and see if I can come up with the percentage of birds in the USA that are killed by cats annually. A simple target figure. Important: the study comes from the American Bird Conservancy. Surprised? Not me. They have an axe to grind. Bird conservationists are always attacking the cat through statistics that are often biased.
Before I go on, I will say that my target figure is impossible to calculate accurately. This is because we do not have a sufficient grasp of the basic information. As is frequently the case, in the current study, the scientists have taken a small sample of cats (60) who wore video cameras around their necks from a specific area of the United States (Athens-Clarke County) and extrapolated the information gathered to make conclusions about the entire country. That is dangerous. It is easy to extrapolate data inappropriately resulting in false conclusions.
Note: “Extrapolation” means taking a sample and expanding the data from it. It is not necessarily accurate for obvious reasons
I present a spreadsheet below showing my calculations based on the information from the study referred to.
Let me say that they concluded that all cats (feral and domestic) kill “at least 500 million birds”. My calculations using their figures conclude the figure is higher at 1,123,516,800. But as I said, it is conjecture. The references to B10 and B11 etc. is reference to the spreadsheet cell. You can’t see the cell references in this published version (that is just the way Google does it). You can see this spreadsheet in larger format on this page: Birds killed by all cats.
As you can see my calculations result in the figure of 7.49% of all birds in the USA killed by all cats in the USA. A relatively low percentage and one that does not incline one to believe that the cat is wiping out native bird species.
There is plenty of argument too about the non-native cat killing the native bird. I don’t think that this a good argument. It is a false argument that places more value on one animal than another. Seems crazy to me. Animals don’t observe national boundaries. And we import them anyway. So how can we blame the non-native species?
The most important conclusion to draw from the the University of Georgia and National Geographic study is: Don’t believe the extrapolated conclusions as they are not reliable enough.
This is the page where you can see the original news item.
Associated page: Cats don’t decimate bird populations.