Domestic cat preying unlikely to effect population size of prey species

This is quite a difficult subject; how domestic cats affect the population sizes of wildlife. We know that domestic cats that are allowed outside can and sometimes do attack and catch small animals. These are  mammals and birds usually. A lot of people who don’t like cats tend to produce data that more or less says cat preying seriously affects the population sizes of native wildlife and for that reason there should be a serious and concerted attempt to reduce cat populations. In plain language lets kill cats because they kill wildlife. See for example: Shooting feral cats (USA) and Ground shooting of feral cats (Australia). See also the LA Supreme Court case: Feral cats of Los Angeles. I realise that the linked articles are about feral cats but the general principles are the same.

F1 Savannah kitten FOCUS

The truth is that it is extremely difficult to find accurate and truthful data on this subject. And we know the old adage, “Lies, damned lies, and statistics”. Statistics can be used to serve an objective.

I have always felt that the domestic cat does not have an negative impact on wildlife to the point where it should be a concern. For this post I have bought (at the princely sum of $47 – not cheap) access to a research study entitled: Impact of predation by domestic cats Felis catus in an urban area by Philip J Baker et al from the School of Biological Sciences, University of Bristol in the UK. The paper was bought from the Wiley Online Library. The idea is to find a definitive answer to the question: “do domestic cats kill sufficient wildlife such that it should be a concern to us?”

This is a scientific study and hard to read so I will simply attempt to provide a reasonable résumé of the document remaining as objective and unbiased as I can in the process.

The study was carried out by asking people in an area of Bristol (UK) to complete a questionnaire about the number of animals, dead of alive, brought back to the house by their cat if they had a cat. 3,494 questionnaires were handed out and 1243 were completed amounting to a 36% response rate.

The survey produced the following data (this is a summary):

  • Cat density: 229/square kilometre
  • Number of cats: 962 or 28 cats per 100 households
  • 271 dead animals were recorded
  • 87 living animals were recorded
  • The wood mouse was the most common prey species accounting for 62% of dead animals recorded and 82% of the live animals recorded. The actual figures being:
  • 168 wood mice were caught and killed
  • 71 wood mice were caught and not killed
  • 13 house sparrows were killed. The house sparrow was by far the most common bird killed. The blue tit was the next most common.
  • 4 house sparrows were caught and not killed
  • In all 76 birds were caught and killed

The conclusion of the study was, “Collectively, despite occurring at very high densities, the summed effects on prey populations appeared unlikely to affect population size for the majority of prey species..”

In short, I read this as saying that domestic cat preying does not affect the population of the animals it preys upon.

It is also interesting to note that the “majority of cats (51% in spring and 74% in winter) failed to return any prey. In other words most domestic cats don’t catch wildlife. My lady cat who is 18 has caught one mouse her entire life and she didn’t eat it!

It is also interesting to note that of all the households that took part in the survey (89) 52 households containing 77 cats killed 212 animals. This represents 78% of all the killed animals. The total number of cats in the survey was 131. Accordingly 59% of the cats killed 78% of the prey. Clearly as mentioned some cats are hunters and some are not interested confirming once again that cats are individuals.

A previous post on this subject and which I would ask visitors to read in conjunction with this one, came to similar conclusions: Domestic cats do not deciminate bird populations. This earlier post recites an RSPB study that concludes that cats prey on dying and sick mammals and birds which would have died anyway. And as can be seen by the above data the domestic cat prefers to prey on ground dwelling animals as they easier to catch. That should silence the bird conservationists who tend to criticise the cat unjustifiably.

Michael Avatar

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Domestic cat preying unlikely to effect population size of prey species

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Jan 21, 2011 Thanks Finn
by: Michael

Yes, we humans are the real killers. We love to find fault with other animals and tend to ignore the havoc that we create, trampling over nature as if we owned it and wiping out species hither and thither.

Thanks for reminding me of the human condition.

Michael Avatar

Jan 19, 2011 Cats and birds – and humans!
by: Finn Frode, Denmark

Thanks a lot, Michael, for your summary of the Bristol reseach study. I think those facts are well worth $47. 😉

I’m a bird lover as well as a cat lover, and I can only repeat my comment from 2009 in another page:

“In Denmark the number of house sparrows have been declining for years, but it seems for a large part to have been caused by the way we build our houses. House sparrows prefer to nest under the roof and in similar places, but modern construction methods have closed all those little gaps and openings that there were plentiful in the old houses. The decline of the house sparrow has actually allowed it’s cousin the tree sparrow into our gardens, because the latter is used to nesting in the bushes and trees of the forest.

Also for many years the European magpie was blamed for the decline in small songbirds, because they raid the nests of other birds. Recent studies however, have shown that the number of songbirds is in no way smaller in gardens where magpies roam compared to the gardens without them. An explanation could be that they prey mainly on weak and sick birds – and raid the nests of those birds not smart enough to hide the nest in a safe place. It’s cruel, but that’s what nature is like.

There are cats and magpies in the gardens below our windows – and plenty of small songbirds nonetheless. Their numbers have actually increased over the last couple of years, but that is probably due to some extraordinary mild winters. So the cats are in no way guilty of decimating bird population around here.

I worry much more about the chemicals that go into the food chain. When the insects are poisoned, so will the birds be.”

Kathlin sums it alls up beautifully by saying:

“Domestic and feral cats are not capable of negatively impacting the populations of songbirds or any other wildlife anywhere near as much as HUMAN activity does.”

Finn Frode avatar

Jan 18, 2011 Thanks Kathleen
by: Michael

Thanks Kathleen for reminding me that the human race kills wildlife at an astonishing rate, far in excess of anything the domestic cat can ever achieve although in typical human manner we try to brush that under the carpet and put the blame elsewhere.

Kathleen, I need to contact you regarding the St. Louis anti-declaw demonstration.

Could you email me: mjbmeister [at] ?


Michael Avatar

Jan 18, 2011 great article
by: Kathleen

Thanks for writing this, Michael. I’ve been saying this every chance I can get. Domestic and feral cats are not capable of negatively impacting the populations of songbirds or any other wildlife anywhere near as much as HUMAN activity does.

Jan 18, 2011 Post Script
by: Michael

This is a related topic:

Cat preying a priority over eating

Michael Avatar

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