An Act to Include Cats in the Laws Governing Animal Trespass

An Ethical and Scientific Position Against LD 644, An Act to Include Cats in the Laws Governing Animal Trespass

6 min readApr 6, 2023

Adapted from an original essay for the Maine Animal Coalition.

by Michael Burrows, PhD.

Mike holds a PhD in public policy from Duke University, specializing in demography, environmental sociology, and quantitative methodology. In this article for the Maine Animal Coalition blog, he discusses the implications of a proposed anti-cat bill (now dead) on the wellbeing of cats across Maine — particularly potent in the context of the state’s strict animal trespass legislation. Mike aptly refutes the alleged rationale for and the science behind this potentially destructive policy.

The Issue in Question

Rep. Vicki Doudera (D-Camden) has proposed legislation adding cats to Maine’s animal trespass law. This change is intended to dramatically reduce the ability of the cat population to explore, socialize, and, most controversially, hunt. In a recent email, the Maine Animal Coalition linked to information provided by Cornell Labs, which offers a mainstream perspective on this issue and likely led many to conclude that cats are best kept indoors. However, the destructive capacity of the free-ranging cat is not as settled as conservation orthodoxy suggests, and there are other considerations at play beyond the matter of birds.

Our collective responsibility toward cats and the species with which they interact is itself a topic of lively and ongoing debate within the scientific and ethical communities, and one in which contemporary research points in a different direction than mainstream conservationists may think.

What Would the New Law Mean for Cats?

Maine’s law against animal trespass goes so far as forfeiture, where an animal can, like any property, be seized by law enforcement and sold. This outcome seems unlikely, but shelters and veterinarians have expressed concerns about the removal aspect of the law, which could inundate shelters and increase euthanizations. While this possibility is jarring, we should not lose sight of the mundane but more broadly relevant restriction — a fine of $50 to $500, which is likely to discourage guardians from allowing their cats to spend time outdoors. If effective, the threat of this fine (and escalating punishment associated with it) is likely to significantly harm the well-being of cats who, in many cases, are far happier and healthier with the opportunity to stretch their legs.

The (Semi-)Domesticity of the House Cat

As most humans that enjoy interactions with cats have likely learned, cats are skilled hunters. Of course, they were domesticated for that very reason, and continue to be deliberately employed in that capacity by many in Maine as barn cats. With the ability to more or less fend for themselves, they have been aptly described as “awkward subjects for domestication“. Many cats continue to hold commensal relationships with humans. Because feral cats tend to fend for themselves successfully, the species challenges the definition of being fully domesticated.

Though it is obvious that many cats treasure their outdoor time, the responsibility of human guardians to protect birds by keeping cats indoors is mostly uncontroversial, even among those who criticize LD 644. As noted in the Portland Press Herald, “even some opponents of the bill acknowledged cat owners need to be educated about the danger their pets pose to birds if allowed outside.” However, this widely accepted perspective is outdated and does not reflect the state of the science. Contemporary research grounded in nuanced ecological relationships and ethical considerations casts much doubt on the usefulness of this legislation.

Photo by Dimitar Stevcev | Unsplash

Bird Mortality

Many in the conservation community have concerned themselves with estimating the number of birds that fall victim to cats, and these claims are the centerpiece of LD 644. Cornell Labs prominently features estimates by Loss et al. (2013), which assert that up to 4 billion birds are killed each year by free-ranging cats (for comparison, American humans eat around 8 billion chickens per year). The Maine Audobon Society cited the same source in its testimony on February 27, 2023, as did the Press Herald’s editorial board in declaring “that bird populations are at risk from cats is in no doubt”.

Unfortunately for supporters of LD 644, that bird populations are at risk from cats is in doubt. In fact, the scientific consensus is much more nuanced, summarized here in two related points.

First, despite bird mortality resulting from cat predation, there is no scientific evidence that cats are causing bird populations to decline. Indeed, if accurate, 4 billion birds may be an appropriate level of predation for a total bird population of over 20 billion and in an ecological context where other predators have been mostly driven out of existence. The effect of cat predation could be mostly compensatory instead of additive, as cats tend to be able to capture sick or weak individuals. Second, the effect of cats in one ecological context cannot be generalized to another. Applying findings from highly specific case studies to the world at large simply does not yield useful information, and when the case studies themselves are highly motivated, then the bias is extraordinarily likely to be perpetuated.

There are many sources of bird mortality. What the Maine Audobon Society and others state as fact — that cats are the primary human-caused threat to birds — is a distraction from larger threats to biodiversity, such as climate change, economic expansion, the loss of wild habitat, and the extermination of predators like coyotes and wolves.

Including Imagined Costs, Ignoring Known Benefits

Those in favor of LD 644 seek to limit the well-being of cats in order to protect bird populations. The advertised benefit of this bill — protecting bird populations — may be largely imagined. To make this legislation credible, its backers should provide evidence of the impact of free-roaming cats on specific bird populations in Maine (a scientific question), and attempt to define an acceptable level of predation for this predator-prey relationship (a values judgment that should be arrived at through democratic discourse). They should compare the costs and benefits of this highly restrictive legislation to other approaches in reducing bird predation that have shown much promise, such as:

Those considering the consequences of this bill should also consider several of the documented benefits of free-roaming cats to human and non-human populations, which can in certain contexts include:

Those truly concerned with animal wellbeing must be willing to challenge conservation orthodoxy on this important issue. All else aside, the known harms that would be done to Maine’s free-roaming cats are not worth the hypothetical and poorly-sourced claims of benefits.

I applaud the Maine Animal Coalition for not supporting LD 644, but ask that it go further and oppose this legislation. LD 644 would inflict much known harm on our state’s cats — from limiting their ability to live a full and satisfying life to the possibility of needless killing — and would offer only hypothetical and uncertain benefits for birds, who will continue to suffer air pollution, habitat loss, and other more profound miseries than cat predation.

Above all, I ask that Maine’s conservation groups heed their own call for a “science-based approach to education, conservation, and advocacy” and cease fueling an unwarranted moral panic over cats.

Kim Hightower is the communications specialist for PAN Works.

Please visit PAN Works for more about our work on ethics and animal wellbeing.




People•Animals•Nature (PAN) is a publication of PAN Works, a centre for ethics and policy dedicated to the wellbeing of animals.