The Cornell Lab’s Perspective on Cats and Their Impact on Bird Populations

The Cornell Lab of Ornithology, an organization dedicated to the study and conservation of birds, acknowledges that many of its staff and ornithologists are cat owners themselves. However, this fondness for feline companions does not overshadow a significant concern: the substantial impact that free-ranging cats have on native wildlife, particularly birds. This article aims to explore the Cornell Lab’s stance on this issue, backed by scientific evidence, and to shed light on the responsibilities that come with cat ownership.

Understanding the Scale of the Problem

In the United States alone, an estimated 60 to 100 million free-ranging, unowned cats exist. As non-native predators, these cats pose a significant threat to native wildlife. Conservative estimates suggest that they are responsible for killing between 1.3 and 4 billion birds and 6.3 to 22.3 billion mammals annually within the U.S.. This situation is deemed unnatural and has a tremendous toll on the continent’s native wildlife. Consequently, as a conservation organization, the Cornell Lab recognizes the responsibility to address this human-caused problem.

The Hardships Faced by Outdoor Cats

Beyond the impact on wildlife, allowing cats to roam freely poses significant risks to the cats themselves. Outdoor cats often lead short lives marked by hardship, disease, and injury. They are susceptible to traffic accidents, attacks from predators or other cats, and the contraction of various diseases. On average, outdoor cats live less than half the lifespan of indoor cats. Furthermore, outdoor cats can transmit diseases such as toxoplasmosis to humans and other wildlife, including sea otters and Hawaiian monk seals. Many cat advocates, alongside those concerned with bird and public health, agree that reducing the number of free-ranging cats is beneficial for all involved, though opinions may differ on the urgency and methods.

The Cornell Lab’s Stance on Trap-Neuter-Return (TNR)

Trap-Neuter-Return (TNR) is a practice where unowned cats are captured, vaccinated, spayed or neutered, and then released back into their environment. While intended to manage and potentially reduce populations over time, scientific studies have highlighted complications that lead to ineffective outcomes. Based on this research, the Cornell Lab of Ornithology does not support TNR as a primary management approach to mitigate the negative impacts of feral cats on wildlife.

Several issues contribute to the ineffectiveness of TNR:

• Encouragement of Colonies: TNR can inadvertently encourage people to release more cats into existing colonies, potentially increasing the overall cat population compared to no intervention.
• Reproductive Potential: Cats have a high reproductive rate. Combined with the challenges of capturing them and the sheer number of cats present, it becomes exceedingly difficult to spay or neuter enough individuals in a colony to control their numbers. Models indicate that for TNR to be effective, 71% to 94% of all cats in a colony must be sterilized. Any introduction of un-neutered cats or new abandonments significantly hinders success.
• Contribution to the Problem: Feral cat colonies are a significant part of the issue, with unowned cats responsible for an estimated 69% of all cat-killed birds in the U.S..
• Public Health Concerns: From a public health standpoint, TNR programs do not effectively reduce the risk of toxoplasmosis or rabies exposure for humans. Studies suggest that TNR programs are less effective at reducing feral cat populations than trapping and euthanizing them. One study indicated that trap-euthanasia could eliminate a large colony within two years, while the more expensive TNR option was unlikely to succeed within 30 years. Euthanasia is often the most effective treatment, especially when there is ongoing immigration or release of new cats into the population. The National Association of State Public Health Veterinarians has concluded that free-ranging feral cats and TNR programs pose risks to public health.
• Welfare of Cats: TNR does not address the inherent risks and hardships that outdoor cats face, such as injury, disease, predation, vehicle collisions, and fights with other cats, all of which contribute to a significantly shorter average lifespan. Some animal welfare organizations, like People for the Ethical Treatment of Animals (PETA), also oppose TNR for these reasons.

Human Responsibility and Cat Ownership

While it’s true that human-caused environmental problems are severe, it’s crucial to recognize that the issue of free-ranging cats is also a human-created one. Humans introduced cats to continents where they are not native, and continue to contribute to their growing numbers through irresponsible pet ownership, such as failing to spay or neuter pets, abandoning cats, or feeding feral colonies. This has led to tens of millions of cats living in a semi-wild state, causing significant harm to native birds and other wildlife. Addressing this issue is therefore our collective responsibility.

It’s estimated that cats kill 1.3–4 billion birds each year in the U.S. alone, a staggering number even when compared with the next-largest sources: 599 million estimated to be killed in collisions with windows and 200 million killed by automobiles. Image from the 2014 State of the Birds Report.It’s estimated that cats kill 1.3–4 billion birds each year in the U.S. alone, a staggering number even when compared with the next-largest sources: 599 million estimated to be killed in collisions with windows and 200 million killed by automobiles.

Addressing the Broader Environmental Picture

The Cornell Lab acknowledges that to effectively save birds, numerous human-caused challenges must be addressed, including habitat loss and degradation, which is the primary threat. However, in North America, cats rank as the second-largest human-related cause of bird deaths, following habitat loss. The sheer number of outdoor cats, both owned and unowned, contributes to this devastating toll. While bird populations are resilient due to reproduction, the current level of predation is unsustainable and requires urgent attention before irreversible damage occurs. Studies on islands, where cats have had a profound impact, demonstrate their potential to cause declines, reduced distributions, or extinctions of various species. Given that one-third of all North American bird species are in need of urgent conservation action, mitigating threats like predation by cats is essential.

Finding Common Ground for a Humane Solution

There is indeed common ground between those who advocate for cats and those who advocate for birds. Both groups are fundamentally pro-animal and pro-nature. A shared understanding exists that much of the current problem stems from irresponsible or uninformed pet ownership. Promoting the importance of spaying and neutering pets, never abandoning cats, and encouraging adoption are crucial steps. Furthermore, both sides agree on the need for humane solutions that consider the well-being of both cats and the wildlife they impact.

Keeping cats indoors is also presented as a pro-cat stance, as it safeguards them from predation, violence, car accidents, and diseases prevalent in outdoor environments, thereby extending their lives.

Keeping Your Cat Entertained Indoors

For cat owners considering keeping their pets indoors, various enrichment activities can ensure their feline companions remain happy and stimulated:

• Engage in regular playtime with your cat.
• Consider adopting a second cat to provide a playmate.
• Construct a “catio” or an outdoor enclosure that allows safe access to the outdoors without posing a risk to native wildlife.
• Leash-train your cat for supervised walks, as some cats genuinely enjoy this experience.

Conclusion: A Shared Responsibility for Wildlife and Pets

The Cornell Lab of Ornithology’s position on the impact of cats on bird populations is rooted in scientific evidence and a commitment to conservation. While acknowledging the love many have for their feline companions, the organization emphasizes the critical need to address the ecological consequences of free-ranging cats. By promoting responsible pet ownership, advocating for indoor cats, and supporting evidence-based solutions, we can work towards a future where both beloved pets and native wildlife can thrive. Raising awareness within communities and making informed choices about our pets are vital steps in protecting the natural world for generations to come.

References

• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Lohr, K. T., et al. (2013). Costs and benefits of trap-neuter-release and euthanasia for removal of urban cats in Oahu, Hawaii. Conservation Biology, 27(1), 64-73.
• Roebling, H. G., et al. (2014). Rabies prevention and management of cats in the context of trap–neuter–vaccinate–release programmes. Zoonoses and Public Health, 61(4), 290-296.
• Schmidt, P. M., et al. (2009). Evaluation of euthanasia and trap–neuter–return (TNR) programs in managing free-roaming cat populations. Wildlife Research, 36(2), 117-12.
• McCarthy, M. A., et al. (2013). Effect of high-impact targeted trap-neuter-return and adoption of community cats on cat intake to a shelter. Journal of the American Veterinary Medical Association, 243(4), 502-511.
• Medina, F., et al. (2011). Cats on islands: unique evolutionary and conservation perspectives. Global Change Biology, 17(7), 2376-2388.
• National Audubon Society. (2016). 2016 State of North America’s Birds Watch List. Retrieved from http://www.stateofthebirds.org/2016/
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications, 4(1), 2380.
• Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of