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

SIMPLE SUMMARY: Strong public support in the United States for the non-lethal management of free-roaming cats has prompted an increase in the practice of trap-neuter-return (TNR) over the past quarter-century, yet a paucity of analyzable data exists. Data sets collected by citizen scientists are likely to play an important role in filling this information void. A citizen scientist in Chicago, Illinois, recorded significant reductions in a free-roaming cat population as the result of a neighborhood TNR program. 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 concurrent TNR programs in the Chicago area are compatible with these findings. ABSTRACT: 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.