If you’ve ever owned an outdoor cat, they have likely brought home a dead bird at least once.
While a single cat killing a bird or two isn’t a big deal, a whole bunch of cats can easily take down a sizeable portion of the bird population. Most birds aren’t designed to escape from the hoard of cats that suburban areas often release.
With so much killing, it may be surprising that cats are not an existential threat to the bird population. Read on to learn more!
DISCLAIMER: The following article is for informational purposes only. At Hepper, we appreciate that matters concerning the conservation and management of animal populations can be contentious, with many legitimate alternative viewpoints. However, our official editorial position is that cats should be spayed and neutered for the general welfare of the environments they inhabit. Hepper supports the ethical treatment of all animals.
1. Cats Kill Between 1.3 and 4 Billion Birds Annually
Estimating exactly how many birds are killed by cats is difficult. Many studies have tried, and not all of them are based on rigorous scientific estimation.
Particular cats kill more birds than others, so it doesn’t make sense to multiply the number of cats by an average “bird kill rate” and call it a day.
One of the newest studies to be published estimates the kill rate to be around 1.3 to 4 billion birds. They used a systematic method for calculating this rate, taking different feline predatory rates into account.
The difference between 1.3 billion and 4 billion is significant. This extensive range is primarily due to estimation in the general cat population size. We don’t know exactly how many cats are owned nationwide, making doing any calculations difficult. Furthermore, the unowned cat population is even less known.
2. Unowned Cats Kill Three Times the Number of Birds as Owned Cats
Feral cats are the most significant predators for birds, killing an estimated three times the number of birds as owned cats. Much of this is because they spend their time outside, so they have more opportunities to kill birds.
Feral cats also need to eat and may hunt to do so. Owned cats are usually opportunistic hunters, killing birds only if they have the opportunity. Feral cats may seek out birds because they don’t have a meal waiting for them at home.
Catch-and-release programs can potentially save billions of birds. By lowering the overall feral cat population, we can save the lives of many birds.
3. Native Species Are the Most Common Targets
For the most part, cats seem to prey on native birds the most. Only an estimated 33% of the birds killed are non-native species.
Therefore, cats are likely not to keep invasive species in check. The native animals seem to pay the highest cost for the introduction of cats into their habitat.
4. There Are Fewer Birds Than You Think!
We see birds all the time, everywhere. Most people believe that there are more than enough birds, so the few that cats kill aren’t a huge deal.
However, this isn’t the case. The habitat of North American land birds makes them highly susceptible to domestic cats.
Currently, their population is estimated to be between 10 and 20 billion. If cats are killing 4 billion birds a year, it’s easy to see how that would make a substantial dent in the overall bird population. Cats seem to be killing a sizeable fraction of all the birds currently native to America.
5. Cats Have Contributed to 33 Extinctions Around the World
One particular study took a look at invertebrate populations on islands after cats were introduced. They found that the cats could easily prey on many of the animals on the island, as they were unaccustomed to living with cats and had no natural defenses against them.
Therefore, it is likely that cats have a significant impact on biodiversity. While this study was done specifically on an island, we must be careful about attributing the same conclusion to other areas.
Cats contributed to at least 33 extinctions around the world — all on islands, as that’s where the study took place. It is possible that other extinctions were contributed to, but we can only speculate.
A lot of interesting information about cats’ impact on wildlife can be found in this study.
6. Cats Are the Main Threat for 8% of the World’s Critically Endangered Animals
The same study found that much of the population decline of 8% of the world’s endangered animals was caused by cats. Birds are included in this statistic. In other words, cats are the main reason that these endangered animals are declining.
If cats weren’t there, these animals likely wouldn’t be quite as endangered!
7. The Effect of Diseases Spread by Cats Is Unknown
Cats also kill birds indirectly through the spread of diseases. We don’t know the rate at which the cats spread these diseases, as there have been no studies on them yet. However, the Centers for Disease Control and Prevention (CDC) has an exhaustive reference of diseases known to be carried by cats that affect humans and other animals. These include:
Campylobacteriosis (Campylobacter spp.)
Cryptosporidiosis (Cryptosporidium spp.)
Giardiasis (Giardia duodenalis)
MRSA (Methicillin-Resistant Staphylococcus aureus)
Bereft of studies on the relationship between cats and birds vis-a-vis disease transmission, it’s absolutely reasonable and logical to assume that transmission has the potential to occur.
8. Not All Cats Are a Threat to Birds, Though
You can rest assured that most cats aren’t a threat to birds. Indoor cats don’t kill any birds, and they make up the large majority of the cat population.
Estimates currently set the indoor cat ratio to about 2/3 to 3/4 of the whole domestic cat population. These cats don’t set foot outside and are completely harmless to birds. They simply don’t get a chance to kill them!
The most likely animal that these cats will prey on is the occasional house mouse, a species that is not endangered in the least.
Even the indoor cat that occasionally escapes outside likely isn’t harming birds that much. Instead, it’s the cats that go outside every day that we have to worry about.
Of course, feral cats seem to be the major problem, and they spend all their time outside!
We recommend keeping your domestic cats indoors. These felines are safer there and have less of a chance to prey on native birds. It’s simply a better place to be for everyone. However, feral cats do the most damage, and no one is around to make sure they spend most of their time indoors.
Controlling the feral cat population is extremely important to help local birds. Catch-and-release programs are essential to lower the feral cat population quickly. Once all feral cats in a colony have been fixed, their population can decline quite dramatically.
For instance, a cat colony can dwindle to only a few members after 10 years. Feral cats do not have extremely long lifespans. If they aren’t reproducing, the colony will disappear in only a few years.
9. Up to 79% of Baby Birds May Be Killed by Cats
Studies on specific bird species, like the catbird, have found that cats may kill as many as 79% of fledglings. Fledglings are particularly vulnerable to cats because they don’t have many places to hide in suburban areas.
This results in a dramatic decrease in the bird population!
This statistic isn’t counting the fledglings that die of other causes either. That leaves very few birds to reach adulthood.
Final Thoughts
Cats kill an enormous number of birds each year. However, the exact amount is challenging to estimate.
While you should keep your cat indoors to prevent possible predation, the main problem seems to be feral cats. They kill as many as three times the number of birds as pet cats. Many of the birds killed are fledglings, though adults are sometimes preyed upon as well.
Therefore, controlling feral cat populations is essential to helping birds. Keeping your cats indoors may help, but the real solution will come from decreasing the feral cat population.
Featured Image Credit: Alexas_Fotos, Pixabay
Contents
- 1. Cats Kill Between 1.3 and 4 Billion Birds Annually
- 2. Unowned Cats Kill Three Times the Number of Birds as Owned Cats
- 3. Native Species Are the Most Common Targets
- 4. There Are Fewer Birds Than You Think!
- 5. Cats Have Contributed to 33 Extinctions Around the World
- 6. Cats Are the Main Threat for 8% of the World’s Critically Endangered Animals
- 7. The Effect of Diseases Spread by Cats Is Unknown
- 8. Not All Cats Are a Threat to Birds, Though
- 9. Up to 79% of Baby Birds May Be Killed by Cats
- Final Thoughts
