According to the Jerusalem SPCA, the only humane way to control animal over population, is to spay and neuter. I do not believe this. I have been told by a number of Rabbanim that it is usser to do this. I believe that HaShem is merciful and would not set before us an imposable task.
What is the hallachic solution to animal over population?http://wejew.com/media/8774/Visit_the_Jerusalem_SPCA_Documentary/