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Animals (Basel). 2018 Jan 18;8(1). pii: E14. doi: 10.3390/ani8010014.

A Case Study in Citizen Science: The Effectiveness of a Trap-Neuter-Return Program in a Chicago Neighborhood.

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Independent Researcher, 4758 Ridge Road, #409, Cleveland, OH 44144, USA.
Best Friends Animal Society, 5001 Angel Canyon Road, Kanab, UT 84741, USA.


The use of trap-neuter-return (TNR) as a method of managing free-roaming cat populations has increased in the United States in recent decades. Historically, TNR has been conducted most often at a grassroots level, which has led to inconsistent data collection and assessment practices. Consequently, a paucity of analyzable data exists. An initiative is underway to standardize TNR program data collection and assessment. However, it could be some time before scientifically sound protocols are implemented on a broad scale. In the interim, sets of data collected by nascent citizen scientists offer valid opportunities to evaluate grassroots TNR programs. The purpose of the present study was to examine the effectiveness of a TNR program conducted by a citizen scientist located in Chicago, Illinois, where a county law permitting TNR was enacted in 2007. Colony populations, when grouped by the number of years enrolled in the program, declined by a mean of 54% from entry and 82% from peak levels. Results from coexistent TNR programs in the Chicago area are consistent with these findings.


TNR; citizen science; feral cats; free-roaming cats; management; sterilization; stray cats; trap-neuter-return

Conflict of interest statement

In recognition of MDPI policy and our ethical obligations as researchers, the authors acknowledge that the funding sponsors provided general guidance for the design of the study and were periodically apprised of project status during data collection, analysis, and interpretation; and the writing of the manuscript.

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