The Humane Society of Sumter County is a PRIVATE non profit organization.
humane society of sumter county florida. - Bing
As opposed to a public non profit organization.
The Difference Between Public & Private Non-Profit Organizations | Chron.com
I know of one way to solve the problems of not killing animals. The group could buy a piece of rural property and keep the animals there until their natural death. It would take a lot of fund raising but it is a possibility.