Cats and birds have a long, complicated history. On one hand, cats are natural predators of birds. Their instincts drive them to hunt and kill smaller animals, including birds. On the other hand, cats and birds can coexist peacefully under the right circumstances. So are cats inherently toxic and dangerous to bird populations? Or can they live together without much conflict? Let’s take a deep dive into the science and research around cats and birds.
Are cats predators of birds?
Absolutely. Cats are obligate carnivores, meaning they need to eat meat to survive. Their bodies and instincts are finely tuned for hunting. An estimated 30% of a feral cat’s diet consists of birds. Cats are also opportunistic hunters. Even well-fed house cats will hunt when given the chance.
It’s estimated that cats kill between 1.3-4 billion birds per year in the United States alone. The exact number is hard to pin down. But multiple studies have found that cats are responsible for a substantial amount of bird deaths each year:
| Study | Estimated birds killed by cats per year |
|---|---|
| Loss et al., 2013 | 1.3-4 billion |
| Blancher, 2013 | 2.4 billion |
| U.S. Fish & Wildlife Service, 2021 | 2.1 billion |
So do cats single-handedly threaten bird populations? Not necessarily. But scientific evidence clearly shows they are efficient bird hunters that kill billions of birds in the U.S. alone each year.
Do cats harm wild bird populations?
Many conservationists are (rightfully) concerned about the impact of cats on wild birds. Songbird populations have declined significantly in recent decades. And predation by cats is one contributing cause.
However, the overall impact depends a lot on context. Feral and outdoor cats do the most damage to local bird populations. But even then, habitat loss and other issues are usually greater threats.
Well-fed, indoor house cats aren’t a major driver of songbird declines. Unless they are allowed to roam outdoors unattended. Then they contribue to the issue.
Here are some key considerations around cats and bird populations:
– Feral cats are likely the biggest problem. They live entirely outdoors and hunt frequently. Feral cats are estimated to kill much higher numbers of birds than owned pets.
– Outdoor, owned cats also contribute significantly to bird deaths. They kill an estimated 1.1-2.6 billion birds per year. Kept exclusively indoors, they cause far less damage.
– Pet cats with outdoor access kill lots of birds. But their exact impact depends on factors like: bell collars to warn birds, time spent outdoors, presence of natural cover, density of local bird population, and supplemental feeding. With management, owned cats can coexist with birds.
– Habitat loss and pesticides are generally bigger threats to bird populations. But predation by cats exacerbates other issues facing wild birds.
The impact on any one bird species also depends on its vulnerabilities. Larger, healthier bird populations can better absorb predation losses. But cats may push smaller, threatened populations over the edge. Context matters.
Overall, feral and outdoor cats do drive sizeable bird deaths. But their exact impact on bird populations depends on local context. With management, owned cats can live harmoniously with nature. But un-owned cats and unsupervised pet cats pose the biggest risks.
Do cats spread diseases to birds?
In addition to direct predation, cats can also spread infectious diseases to birds in some cases.
Some common examples include:
– Salmonellosis – Cats carry Salmonella bacteria that can spread to birds through feces contamination.
– Toxoplasmosis – Cats are the definitive host for this parasitic disease. Birds and other species can become infected via cat feces.
– Campylobacter – Birds and cats host Campylobacter bacteria, which can spread between species.
– Fleas and ticks – Cats may introduce fleas and ticks to backyard birds at bird feeders.
However, disease transmission requires close contact and is relatively uncommon. Diseases spread much more easily within a bird or cat population than between species.
So while cats can introduce certain diseases, they are a minor route of disease transmission to wild birds in most cases. Direct predation is a greater hazard from cats. Proper hygiene around pets can prevent most disease issues.
Do cats harm baby birds?
In addition to hunting adult birds, cats may also kill vulnerable baby birds in ground nests or tree nests within reach.
Kittens and younger cats are especially likely to kill baby birds out of curiosity and play. But adult cats are capable hunters of young birds as well.
Documented cases show pet cats have killed nestlings of many common species, including:
– Robins
– Sparrows
– Finches
– Blackbirds
– Wrens
And endangered species are also at risk:
– In 2012, feral cats were linked to the deaths of over 250 piping plover chicks in the Great Lakes region. The plover is an endangered shorebird.
– Feral cats are a known predator of the equally endangered Florida scrub jay, especially targeting juvenile and eggs.
In general, ground-nesting species and any accessible tree nests are vulnerable. This includes many songbirds.
Baby birds have essentially no escape from a determined cat. And the destruction of eggs or chicks can deal a major blow to local breeding populations. Birds that nest on or close to the ground are at greatest risk from marauding pet cats in the neighborhood.
Do cats damage local ecosystems?
When cats kill birds–or other wildlife like lizards and rodents–they can potentially disrupt local ecosystems.
As discussed above, the exact impacts depend greatly on context. But invasive cats concentrated in certain areas do cause measurable ecological harm. Effects include:
– Direct declines in prey species. Even if cats don’t fully eradicate a prey population, they can suppress numbers.
– Imbalanced predator-prey dynamics. With fewer natural predators, cats may imbalance local food chains.
– Spread of diseases. Feral cats are more prone to carry infectious diseases transmissible to wildlife.
– Loss of native predators. Disease and competition from cats can pressure native predatory species like raptors.
– Soil impacts from cat feces. High volumes of fecal matter from cat colonies impacts soil nutrients and microbes.
– Spread of invasive plants. Cat fur aids distribution of invasive seeds.
For example, one study on tropical atolls found cat predation was pushing native bird species towards extinction. Removal of cats allowed bird populations to rebound.
Similar ecosystem impacts have been documented in other contexts like urban parks and nature reserves where invasive outdoor cats concentrate.
Well-managed indoor cats cause far less disruption. But invasive outdoor and feral cats do demonstrably alter ecosystems through predation, disease, soil impacts, and other effects. The scale of the damage correlates with cat population density.
Do cats attract other predators?
In addition to their own hunting, outdoor cats may indirectly attract other wild predators towards bird populations.
Predators like foxes, coyotes, bobcats, bears, and others may follow sources of easy food. Where cats cluster, they provide ready meals for these opportunistic hunters. The predators then stick around the area, increasing risks to local birds.
So while the cat itself causes direct mortality, it also draws in other hunters by its success. Concentrations of feral cats especially can attract foxes and other clever wildlife.
This pair of predators then creates a doubly dangerous situation for birds. One study in California found coyotes were drawn to areas with large feral cat populations, increasing risks to wildlife.
Keeping pet cats indoors removes this unintended lure effect. And controlling feral cat colonies through TNR programs can prevent their aggregation.
So responsible cat management helps minimize risks to birds from both direct cat predation and attraction of other predators.
What birds are most vulnerable to cats?
Certain bird species and families are most vulnerable to cat predation based on their natural histories:
– Small songbirds – Smaller birds are easier prey for cats. This includes especially vulnerable families like sparrows, wrens, warblers, finches, swallows, chickadees, and nuthatches.
– Ground-nesting birds – Birds that nest on the ground like quail, pheasants, and shorebirds are readily caught by hunting cats. Nestlings and eggs are vulnerable.
– Island birds – Isolated island birds evolved without feline predators. They lack protective instincts, making them easy targets for invasive cats. Extinction rates are high.
– Rare and endangered birds – When cats are introduced to areas with endangered endemic birds found nowhere else, the results are often devastating due to lack of defenses.
– Urban adapters – Birds like robins and blackbirds that thrive around humans are abundant targets for outdoor pet cats. Familiarity with yards makes them vulnerable.
– Feeder birds – Backyard bird feeders attract songbirds, exposing them to pet cats lurking nearby. Feeders near cover offer ambush sites.
– Migratory birds – Migrating birds traveling through unfamiliar areas in spring and fall are more vulnerable.
Conclusion
The science makes it clear that cats do kill birds frequently through both predation and disease transmission. Billions of bird deaths are attributable to cats each year in the U.S. alone.
Feral cats and outdoor pets cause the most harm through hunting. Even well-fed cats will hunt due to their natural instincts. Birds of all types are vulnerable to cat predation, but especially small, ground-nesting species.
However, the exact impacts on bird populations depend greatly on context. In areas with large invasive cat populations, ecosystem-level damage is clear. But individual indoor cats under responsible ownership do not pose substantial risks.
With conscientious management of pet cats and feral colonies through TNR, it’s possible to minimize risks to birds. But ultimately, cats are natural hunters of birds that will follow their instincts when allowed to roam free. Responsible cat stewardship together with habitat conservation are the best practices for allowing shared existence of birds and cats.
