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TNR results: Cat population reduced 78% on urban college campus


“Application of a Protocol Based on Trap-Neuter-Return (TNR) to Manage Unowned Urban Cats on an Australian University Campus,” published in the journal Animals, 2018. Complete article available (open access) online here.


This study [1] presents the results of a nine-year trap-neuter-return (TNR) program implemented on the campus of the University of New South Wales in Sydney, Australia. Researchers documented a 78% reduction in the campus cat population despite the arrival of 34 feral cats and kittens over the nine-year observation period.

Key points

Over the span of nine years, researchers documented a 78% reduction in the original campus cat population, from 69 to 15 cats. In addition, they documented 34 new cats and 19 kittens born on campus (14 of which were born to these new cats, some of which were pregnant when they arrived on campus). When all of these categories are considered, a total of 122 cats and kittens were “under management” as part of the campus TNR program, and corresponding population reduction was 88%. Similar results have been documented by other researchers investigating targeted, sustained TNR efforts (including adoptions, when feasible) [2–4].

The last kittens known to have been born to the original campus cat population were born to two resident females one year into the TNR program. Both mothers were subsequently sterilized. These kittens, and the 14 born to new arrivals, were fostered and placed for adoption. This college campus TNR program’s results illustrate the importance of ongoing monitoring to any successful TNR program, as has been documented in other studies [2–5].

Feral cat health and welfare

Over the study period, 20 (24%) of the 85 “resident cats” on campus were euthanized for serious health concerns. Nine (45%) were estimated to be under 5 years of age, five (25%) between 5 and 10 years old, and the other 6 cats (30%) were estimated to be more than 10 years old. Such findings challenge the common misperception of free-roaming/unowned cats living short, unhealthy lives.



  1. Swarbrick, H.; Rand, J. Application of a Protocol Based on Trap-Neuter-Return (TNR) to Manage Unowned Urban Cats on an Australian University Campus. Animals 2018, 8.

  2. Spehar, D.D.; Wolf, P.J. An Examination of an Iconic Trap-Neuter-Return Program: The Newburyport, Massachusetts Case Study. Animals 2017, 7.

  3. Spehar, D.D.; Wolf, P.J. A Case Study in Citizen Science: The Effectiveness of a Trap-Neuter-Return Program in a Chicago Neighborhood. Animals 2018, 7.

  4. Kreisler, R.E.; Cornell, H.N.; Levy, J.K. Decrease in Population and Increase in Welfare of Community Cats in a Twenty-Three Year Trap-Neuter-Return Program in Key Largo, FL: The ORCAT Program. Frontiers in Veterinary Science 2019, 6.

  5. Spehar, D.D.; Wolf, P.J. Back to School: An Updated Evaluation of the Effectiveness of a Long-Term Trap-Neuter-Return Program on a University’s Free-Roaming Cat Population. Animals 2019, 9.


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