This is another attempt, in a study, to discover the impact that the indoor/outdoor domestic cat has on wildlife because of the cat’s natural tendency to prey on mammals and other creatures e.g insects.
It is interesting and I believe cat lovers and cat advocates need to address all issues that relate to the domestic cat both good and bad as it is the only way we can make improvements.
I won’t go over all the mathematics on this because it’ll turn people off but towards the end of this page is a link to a spreadsheet which sets out the figures, which are summarised here.
Basically, this lady in Cape Town South Africa, UCT Masters student, Frances Morling, studied domestic cat predation in two ways. She sent out questionnaires and asked people how many times their cat brought prey back to the home and secondly she fitted video cameras to a small number of cats (10). There were two groups of five cats. One group lived in a classic suburban environment and the other lives on the edge of the suburban environment and countryside.
Based on questionnaires and on the evidence provided by the videos, Frances concluded that, on average, each cat killed about 1 prey item (meaning prey of any type) every 5 days. The exact representation is 0.182 prey items per day per cat (on my calculation from figures on this news report.
I did some spreadsheet work on this and if you take that figure as accurate anywhere in the world, which is a dangerous thing to do because it probably is going to produce an incorrect figure, then in the USA, the indoor outdoor cat kills 3,152,272,727 prey items per year (over 3 bn).
An interesting facet of this study is that 41% of the prey items were small mammals such as mice, 30% of the prey items were invertebrates (e.g. insects), about 11% were reptiles, a little over 9% were amphibians (e.g. frogs etc) and a little less than 7% were birds.
This is where it is tricky making a comparison between a South African study and what happens in America because the sort of prey that a cat will attack and kill in S.Africa will be different to prey in America.
However, it is interesting to note that almost one third of the prey items were insects and by far the lowest percentage of prey items were birds. On my calculations based on the study about 214m birds are killed in the USA every year by indoor outdoor domestic cats.
Obviously this is a very generalised assessment but often you see figures such as 1 billion to 2 billion birds killed by domestic cats in the USA annually which appear to be very high compared to the figure I have calculated. An estimated up to 1 billion birds are killed annually through flying into buildings.
Anyway, I’ll leave it there. The truth of the matter is that thus far no study has conclusively worked out the impact of the domestic cat on wildlife in the USA or any other country for that matter. This is because it is almost impossible to base nationwide figures on a study concerning 10, yes 10, domestic cats (in this case) living in the suburbs of one town in one country.