This letter expresses concern about New York State's approach to managing cats and their impact on native wildlife. Peer-reviewed studies show that cats kill billions of native animals in the US each year, threatening many vulnerable species. Trap-Neuter-Release programs are not effective at reducing feral cat populations across broad scales and may even increase numbers compared to no intervention. Given the threat cats pose to biodiversity, the state must explore new management options, such as treating cats like dogs through licensing and control measures rather than relying on ineffective TNR programs.

1. March 15, 2018
Dear Assemblyman Englebright:
I am writing to express concern about New York State’s approach to managing cats. My main
points, which I expand upon in the following paragraphs, are:
(1) Peer-reviewed scientific studies indicate that cats, a non-native predator, kill billions of
native animals every year, including species of conservation concern,
(2) One popular intervention – Trap, Neuter, Release (TNR) – is not effective across broad
spatial and temporal scales, and
(3) Given our responsibility to manage cats to reduce threats to native biodiversity, we must
explore new management options, which include treating cats more like dogs in terms of
licensing and control.
From a biodiversity perspective, the impact of cat predation is staggering. Cats have been
implicated in the extinction of 33 bird species since the 1600s, and they continue to threaten
dozens of vulnerable species, including piping plover, least tern, burrowing owl, California quail,
and Hawaiian honeycreepers. A recent analysis estimated that free-ranging domestic cats kill 1.4
– 3.7 billion birds and 6.9 – 20.7 billion mammals each year in the US alone (Loss et al. 2013).
This means that cats are the single greatest source of human-caused mortality for birds,
representing approximately 10-20% of the estimated total population of birds in the US. To put
this in perspective, cats are responsible for approximately 4x the number of birds killed by
colliding with widows or buildings, 10x the number killed by vehicle collision, and 120x those
killed by powerlines. The impact of cats is likely exacerbated by the fact that many cat colonies
are often within or adjacent to green spaces, which can severely undermine the efforts of NYS to
protect parks and natural areas. Feral cats also can serve as reservoirs or vectors of parasites and
diseases that can affect pets and humans.
The threat that feral cats pose to people and native wildlife is widely recognized among
scientists, managers, and conservationists, and there is similarly widespread agreement that
increasing populations of free-ranging and feral cats must be controlled. However, the whole of
the scientific literature does not support the efficacy of TNR. Rather, the citizens and native
wildlife of New York State are best served by treating cats like dogs and, as such, remove the
feral animals.
I understand the social-political controversy surrounding the management of feral cats; however,
the science is clear. Overwhelming evidence points to the fact that most TNR programs have
been and are expected to be less effective at reducing populations of feral cats than trap-
euthanasia (Andersen et al. 2004, Longcore et al. 2009). In some cases, TNR may increase
population size compared to no intervention at all (McCarthy et al. 2013). One study found that
trap-euthanize would extirpate a large colony within 2 years, whereas the twice as expensive
TNR was unlikely to within a 30 year timeframe (Lohr et al. 2013). In particular, in cases where
there is some immigration (or release) of new cats in the population, euthanasia is likely to be the
most effective treatment (Schmidt et al. 2009). One of the reasons why TNR is likely to be
ineffective at controlling feral cats is that the establishment or maintenance of cat colonies
encourages release of additional cats (Castillo and Clarke 2003). From a public health

2. perspective, trap-neuter-vaccinate-return programs neither reduce feral cat populations, nor
reduce risk of toxoplasmosis or rabies exposure for human populations (Roebling et al. 2014).
The National Association of State Public Health Veterinarians concluded that free-ranging feral
cats and TNR programs are detrimental to public health.
Even considering the welfare of cats alone, the extent to which TNR is more humane can be
questioned. Feral cats live outside, oftentimes in places where they are likely to lead harsh and
traumatic lives. Free-ranging cats face many hazards, including disease, vehicle collisions,
attacks by other animals, poisoning, and exposure. Indeed, vehicle collision and predation were
the two primary causes of death of cats in the Chicago area (Gehrt et al. 2013). For this reason
as well as due to the impact of cats on wildlife, certain animal welfare groups, such as People for
the Ethical Treatment of Animals, oppose TNR.
Thank you for your consideration.
Sincerely,
Amanda D. Rodewald, Ph.D.
Director of Conservation Science, Cornell Lab of Ornithology
Garvin Professor Professor, Department of Natural Resources
Faculty Fellow of Atkinson Center for a Sustainable Future
Cornell University
159 Sapsucker Woods Rd.
Ithaca, NY 14850
Phone: 607-254-2176
Fax: 607-254-2104
Email: arodewald@cornell.edu
Literature cited:
Andersen et al. 2004. Journal of the American Veterinary Medical Association 225:1871-1876.
Castillo and Clarke. 2003. Natural Areas Journal 23:247-253.
Gehrt et al. 2013. PLOS ONE 8: e75718
Lohr et al. 2013. Conservation Biology 27:64-73.
Longcore et al. 2009. Conservation Biology 23:887-894.
Loss et al. 2013. Nature Communications 4: article 1396.
McCarthy et al. 2013. Journal of the American Veterinary Medical Association 243:502-511.
Roebling et al. 2014. Zoonoses and Public Health 61:290-296.
Schmidt et al. 2009. Wildlife Research 36:117-125.