Bird Buddy Blog

Do cats harm bird populations?

Courtesy of Flickr

Cats catch birds. There’s no disputing it, and it’s never a nice thing to find a bird gift from your furry pal. The question posed by many is does this affect bird populations, and if so, what can be done?

Studies on feline predation in the past have set “cat people” against “bird people”, which is also never a nice thing. It’s perfectly reasonable to love both cats and birds, of course.

But a study released at the beginning of 2013 provoked global outrage after concluding that cats kill an estimated 1.3 billion to 3.7 billion birds a year in the US. Despite the numbers having a sizeable range, anti-cat folks shouted “kill them all” whilst cat-lovers shouted back saying a cull wasn’t the answer and that the report was written with an agenda in mind. Both sides of the argument continue to this day, and of course they will, because that’s what we do best.

What we read in the papers

The report did stress that the huge mortality rate was most likely down to the “unowned domesticated cats” and the concurrent feral population, whilst mentioning that free-ranging domesticated cats were still deemed to cause “substantial wildlife mortality”.

The authors [of the study] nonetheless released a very provocative value into the world.

Once the study was looked into, the data could be considered flawed: it turned out it was actually a review known as a meta-analysis based on several previously published studies; accuracies of meta-analyses raise reasonable concerns in health and medicine. Footnotes to this one did state that as there was no actual known number of “unowned” cats in the US, estimates that were available ranged from 20 – 120 million, again quite a gap. After using a mathematical process to agree on a more conservative number of 30 – 80 million, the authors transposed the findings from known, vastly smaller local populations and bird deaths onto a bigger screen. Never claiming the study was airtight, the authors nonetheless released a very provocative value into the world, based on informed guesswork. The backlash was instant and loud, and soon enough cats had been branded the number one threat to birds, and evil murderers, no less. There has been no conclusive study since that has claimed a link between mainland bird population decline and cats. BirdLife International also cites agriculture and logging as the top two threats to vulnerable species, ranking invasive predators third.

Courtesy of

But no matter – anger and divide ruled the headlines for a long time, which in itself was a good thing as it prompted debate about something that had hitherto not really been discussed before. The impact of cat predation in certain areas was never doubted. But it’s the conclusions drawn from the studies that need to be discussed, and the knee-jerk reaction to slaughter one animal for the benefit of another is an all too common human reaction that can sometimes be the root of a problem, rather than the solution. For example, eradication of cat populations on some Pacific islands has now led to a surge in rat and mustelid populations, who are now free to execute their instinctual survival methods on birds without the added hassle of cats pouncing on them.

Birds at risk

New Zealand, having evolved in isolation over millions of years with no mammals apart from a few bat species, has a unique flora and fauna position in the world. Birds dominated with the consequence of many becoming flightless, filling the niches unclaimed by land mammals. When European explorers greeted those shores with their cats in tow, the late 17th century saw a huge boom in the feral cat population. Perhaps because of this, New Zealand residents actually comprise the majority of worldwide cat owners per head of population, with an estimated 1.4 million kitties to 4.5 million people. That’s a lot of furballs on one island.

The impact of cat predation in certain areas was never doubted.

Similarly, the lush tropical rainforests of Hawaii boasted such a diverse range of birdlife that when cats were introduced in the 1700s, again by Europeans, the impact on the native species was catastrophic. And over the continent they spread.

There is no denying that some species of bird are already extinct, and most likely due to feral cat predation. Species already under pressure are therefore at risk; the International Union for Conservation of Nature, (the IUCN, better known to you and me as the people who list species as threatened, vulnerable and so on) have included Felis catus on their 100 Most Invasive Species list, which also includes starlings and mynah birds.

All good friends

But equally undeniable is the love, friendship and bond that millions of people feel from having cats as pets, or keeping near-feral cats on their land as rodent monitors. Without the support and understanding of the general public, any measures taken with a view to preserving bird species at the expense of the wellbeing of cats will bring upset and anger, so they must be explained and discussed before implementation. There is another way, and that way is always education.

One of the simplest things we can do as cat lovers is to get them microchipped.

Explaining the greater good and demonstrating the value of actions taken not only helps confirm that the chosen path is the right one, it can also expose flaws in the thinking. Blanket tactics such as laying poison down everywhere are never going to win you the popular vote, and can do more harm than good.

Courtesy of Geograph

Proactive rather than reactive steps relying on individuals should also be encouraged. This does relinquish responsibility into the world and compliance is never guaranteed, but the groundwork should already have been laid by explaining why these hopefully one-off harsher steps were necessary, and how they may not need to happen again. One of the simplest things we can do as cat lovers is to get them microchipped. This is usually a free service and is harmless to your beloved chum. The impact of lost cats furthering the feral population cannot be understated, not to mention the pain and heartache of losing your companion with no knowing of what happened. There are still issues with the chipping systems in some places, granted, and always in the next steps with administration of the information on the chip, but those systems are showing that rare thing of improvement with the rise in demand.


We can also encourage bird species to flourish by planting trees and bushes that help birds  protect themselves from predation, and if you have feeders, especially platform feeders, make sure they are away from any fences or walls with ledges nearby if you can. Feed your wild birds, especially in harsh winter months, it does no harm. Get familiar with your local populations and spend some quality time bird-watching, and you’ll also start to recognise who else stalks the neighbourhood. House cats are usually quite easily startled, and a quick and frequent “whoosh!” out the window can eventually deter Mr Tiddles from terrorising the sparrows.

Courtesy of Pikist

We do need to find the balance between cats and the greater natural world, and demonising cats won’t help that. As cat and bird loving individuals, no one wants to live in a world where one species is pitted against the other to survive, and nor should we have to.