There is a lot of very heated debate on free roaming domestic cats (owned and feral). Opponents and proponents have very strong feelings but there is no credible data on just exactly where and how many free roaming cats are out there (except for one or two small localized studies).

This project hopes to collect data about domestic cat numbers in the United States and possibly their movement patterns.

Studies of note:

https://academic.oup.com/jmammal/article/96/5/981/914554/Cats-are-rare-where-coyotes-roam
http://www.kittycams.uga.edu/research.html