Eleventy bazillion bird killing cats

October 4, 2017

When the Australian Government's department responsible for marketing their new cat poison range, was presented with the embarrassing finding that their favourite "75 million native animals killed every day by feral cats" was wildly inaccurate, or as we like to say in Australia - total bullshit - they were left with a problem. How to continue to market their cat-slaughtering strategies, when there was probably ten times less unowned cats than previously thought.

So they fell back on the "feral cats caused the extinction of 22 Australian mammals" meme for a while, but not only was that also quickly discredited with most of these animals having died out rapidly after human settlement 200ish years ago, but that it didn't have the same bang with the media. They needed a BIG number that rolled off the tongue. Something with a wow factor.


Lovely. I mean just LOOK at it. A million birds every day. They must have literally stood back, admired their handiwork and high-fived each other when they came up with this one.

So let's look at the claims and the research paper, which can be found here;

  • These are some of the findings of recently published research by a group of Australian environmental scientists. 
  • Feral cats kill 377 million birds and pet cats kill 61 million birds in Australia every year. 
  • This equates to cats killing more than 1 million Australian birds every day. 
  • More than 99% of these casualties are native birds. 

Let's look at these claims individually, shall we?

"These are some of the findings of recently published research by a group of Australian environmental scientists"

Firstly, it is worth noting that this is a reconciliation of existing studies, rather than a new study. The estimates are based on results from studies on cat density, and another set of nearly 100 studies that assessed cat diet. 

The lead researcher Professor John Woinarski was also responsible for the previous "22 Australian mammals" paper, and is employed by the government's Threatened Species Hub as headed by the Threatened Species Commissioner who issues big-money grants to organisations working in conservation. He is also on the board of the Australian Wildlife Conservancy a major recipient of those grants. The Australian Wildlife Conservancy was the source of the original "75 million native animals killed" meme, as well as the massively overinflated cat population.

So let's just say much of the research already presented on this topic, by these same "researchers" has already been revealed to be less than robust.

Feral cats kill 377 million birds and pet cats kill 61 million birds in Australia every year. 

Firstly, let's just note;

Only one Australian endemic bird species has become extinct from mainland Australia since European settlement (i.e., about 0.3% of Australian land birds), a far smaller number and proportion than for mammals. However, as with the Australian mammal fauna, birds restricted to Australian islands have a high rate of extinction, with eight extinct species.

The one mainland bird that has gone extinct is the Western rufous bristlebird in WA. The reason for its extinction is thought to be "... the destruction of its shrubland habitat which was repeatedly burnt in the early 20th century to create pasture." Of the other eight island dwelling birds, none have been attributed to cats. Rat predation yes, and overhunting certainly. But not cats.

But let's get back to the claims; Feral cats kill 377 million birds. The following calculations are offered;

The average number of birds killed by feral cats in natural environments is 35.6 birds km− 2 yr− 1 About 99% of these mortalities are native bird species. 
On average, a feral cat kills 129 birds per year
With a much sparser evidence base, we also estimate that a further 44 million birds are killed annually by feral cats in highly modified landscapes, and 61 million birds are killed annually by pet cats, summing to 377 million birds killed yr− 1

So breaking that down further;

Legge et al. (2017) estimated that 0.72 million feral cats occur in the ca. 57,000 km2 of Australia that comprise highly modified landscapes (such as rubbish dumps, intensive piggeries, urban areas) where food supplementation for feral cats is unintentionally provided by humans.

In cats who live in and around humans allegedly kill around 170 birds per cat, per year, or 44 million birds are killed annually by feral cats in highly modified landscapes

and 61 million birds are killed annually by pet cats

From national surveys of pet ownership, the population of pet cats in Australia is estimated at 3.88 million (Animal Medicines Australia, 2016). 

We know about one third of cats live exclusively indoors leaving 2.5 million with access to the outdoors, so these cats allegedly kill around 25 birds per cat per year.

And finally truly "feral" cats - feral cats typically consume 272 million birds

Legge et al. (2017) collated and then modelled 91 site-based estimates of feral cat density to derive an estimate of 2.07 million feral cats in largely natural landscapes of Australia

Meaning these cats allegedly kill 131 birds per year.

This equates to cats killing more than 1 million Australian birds every day // More than 99% of these casualties are native birds 

And here is where the study gets truly interesting. If we do take all their calculations and estimations and extrapolations to be true, how does this actually effect birds?

Well, as mentioned above, only one bird has gone extinct on the mainland and this was due to habitat clearing.

What kind of an impact does 1 million birds killed daily have on the overall population?

From the paper

A useful contextual reference point for the number of birds killed by cats per year in Australia would be the total Australian bird population size, however to date there has been no such estimate. 

However, this morning on ABC News, Professor John Woinarski was more upfront when asked directly about the overall population of birds being killed by cats.

It's 3%. There are about 3 billion birds in Australia and cats are taking about 3% of those. We don't really know what the impact is.

(will link to video asap).

What is the impact of taking 3% of a population of anything to the population? Probably not a lot. And that this manageable and normal level of predation by cats, is likely a result of other apex predators (dingoes and then in turn, foxes) being removed by the same agencies now advocating cat poisoning programs. Not abnormal predation, but totally predictable and probably desirable in the protection of birds, by keeping other known predators (rats) from preying on the same birds with even more catastrophic results.

But gosh it sounds dramatic doesn't it?

One million birds a day killed by cats. When you're in the business of marketing cat poison, you're going to need some dramatic information to get the community to abandon their compassion and green light even more culling and killing and poisoning of animals (including people's pets). Unfortunately, as we've seen, the truth sometimes gets lost in the spin, and all the while there are people willing to put their professional reputations on the line to create mythology and memes which demonise cats for simply filling a void caused by previous decades of poisoning, countering this government-funded brutality becomes extremely difficult indeed. Especially when the major animal welfare agencies raising hundreds of millions of dollars supposedly for the protection of cats, continue to remain mum and say nothing about the government's efforts to commercialise cat bait for profit.

Find this post interesting? Share it around.