Trap-Neuter-Return And Citizen Science: A Review From Chicago

Trap-Neuter-Return (TNR), a non-lethal approach to managing feral and other free-roaming cats, enjoys strong public support. While there is some evidence that TNR, when implemented well, can be effective, some critics point out the lack of solid quantitative evidence of consistent success across many contexts. Advocates have started a movement advocating standardized record-keeping and data assessment, but it will take years for a critical mass of such evidence to be gathered and analyzed.

In this study, the authors sought to uncover and share findings of “citizen scientists” who have kept records of TNR implementations in the past. Rather than wait for a golden age of overflowing data based on a common framework, they wanted to explore and analyze any case studies with enough quantitative information to allow preliminary conclusions about TNR’s effectiveness.

Specifically, the authors looked at the Cats in My Yard (CIMY) program conducted in the Humboldt Park section of Chicago. The founder and chronicler of the program kept meticulous records during the entire duration of the program, from 2007-2016. Each colony was given a unique name (along with most of the cats), and census information for each colony was updated on an annual basis, sometimes more frequently. The program tracked each cat’s color; markings; sex; age group; perceived level of socialization; and spay-neuter, ear-tip, and microchip status. New arrivals, deaths, and disappearances were also recorded.

Over the ten-year period of the program, 195 cats were trapped, sterilized, vaccinated, and returned or adopted out. The highest total population across all the colonies occurred in 2012 with 88 cats. The number decreased each subsequent year until only 44 cats were present at the end of 2016. The last known litter of kittens produced by a cat living outdoors in the program area was born in 2009.

As with any research project, the data from one study alone are not sufficient to prove TNR’s effectiveness. To this end, the authors analyzed additional data sets to contextualize the evidence as much as possible. For example, they looked at the dramatic decrease in admitted cats and euthanasia percentages during the same period in Cook County, where the CIMY program was situated. Records from Chicago’s City Animal Care and Control also indicated a decline in stray cat intake well above the national average for U.S. shelters. They also documented the presence of other TNR efforts in nearby Chicago neighborhoods, although there were no data sets as thorough as those for CIMY.

Out of these several imperfect data sets, the authors make a strong argument for the high probability of TNR effectiveness, which would be supported by some other research we’ve covered here as well. The study offers an excellent example of the complexities of data collection where multiple agencies and grassroots efforts intersect. While more consistent and reliable data-gathering processes across TNR programs are certainly desired, the authors are bullish on collection by citizen-practitioners coupled with responsible analysis and interpretation.