Johnson, K.L. and J. Cicirelli (2014). "Study of the effect on shelter cat intakes and euthanasia from a shelter neuter return project of 10,080 cats from March 2010 to June 2014." PeerJ, 2:e646.

This study examined the impact of a Return to Field program in a municipal shelter in San Jose, California. The program included sterilizing, vaccinating, ear tipping and returning healthy, impounded cats to the place they were found, with or without an identified caregiver. Over four years, the shelter’s program garnered decreases in cat intakes (from 70% to 23%), cat and kitten impounds (by 29.1%) and euthanasia for Upper Respiratory Disease (by 99%). [The difference between “intake” and “impound” is not explained.]

Conclusion: Besides the obvious cruelty of returning a healthy, friendly cat to the outdoors, the highlighted text shows why this study does not and, in the case of no caregiver, should not apply to S.F. ACC.