Estimating the Number of Birds Caught by Cats

October 14, 2019

In a recent blog post, we wrote about a new recent article in Science magazine, which focused on the decline of bird populations in North America. Here are some related thoughts.

1. Protecting Birds is What This Company Does

We work every day to help other cat owners protect birds from their cats. We are making a difference in the number of birds caught by pet cats, and we are establishing that our product is useful--not just in North America--but also in the U.K., Europe, Australia and New Zealand.

The long-term goal for Birdsbesafe company is to help greatly reduce the number of birds caught by pet cats. We are already protecting perhaps hundreds of thousands of birds. We would like to protect millions of birds, and to continue on our path of becoming a globally recognized tool for bird conservation.

2. Is the oft-quoted toll of domestic cat predation on birds accurate?

We respectfully disagree with the commonly quoted estimate that says cats in the U.S. kill 1.7 to 3.4 billion birds each year. This figure comes from a 2013 article by Scott Loss et al. It is so widely quoted that people assume it is a hard fact, when it was a modeled estimate, which is open to question. We disagree respectfully--and not for ideological reasons, but because of our experience of ten years time corresponding with a large number of cat owners who have pet cats that they let outdoors.

We know from pet ownership stats that there are about 100 million pet cats in the U.S. Half to two-thirds go outdoors daily. I do not think that the average number of birds caught by housecats is 36 birds. (2.4 billion birds/66 million cats). I think that number is much too high to be true.

Why? From a lot of reporting from cat owners. At Birdsbesafe LLC, we have heard from cat owners continuously for more than ten years. Based on what they say about the number of birds their most problematic cats are catching, it seems unlikely to me that there are 1.7 -3.4 billion birds caught by cats each year. We're not making a model or doing science, but we have the thought that cat predation on birds is more likely to be in the hundreds of millions per year--which of course is still a very high toll on birds and why we want to reduce it!

Our product works for outdoor cats, and so we promote it to help save as many birds as possible. If cat owners do not confine their cats, we think that we offer the next best solution on the market.

3. Does the new report on bird population decline match with the prior estimates of cat predation by birds?

There seems to be a discrepancy between the estimates of bird population decline in the recent article in Science, compared to the 2013 S. Loss estimate.

The newest numbers are showing that in a 50 year period, bird population size decreased by about 3 billion birds. So, how would that align with the earlier estimates of the toll the bird predation by cats being 1.7 - 3.4 billion birds each year? The don't seem to be compatible estimates, so it would appear that the cat predation numbers were much too high.

I hope to see the discrepancy discussed meaningfully by scientists and conservationists. Someone should be able to dive in to the modelling that guides both papers and get some detailed understanding of the discrepancy.

That's all for now. To be continued...

Thanks for caring about protecting cats from birds!

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