FORT WORTH (CBSDFW.COM) – Animal advocates in Fort Worth want to know what happened to a colony of feral cats that lived in Trinity Park.

The cats mysteriously started disappearing a few weeks ago, and now there are none to be found.

For about a decade, Beverly Sims and other volunteers have fed, fixed and vaccinated the feral cats.  “There’s someone out here everyday, rain, sleet, snow, floods, nothing stops these caretakers,” Sims said. “They’re so devoted.”

Lately volunteers have noticed all of the cats are gone, and they fear the worst has happened.  “They’ve just disappeared into thin air,” Sims said, “We’ve searched this area over and over and over and we’ve found nothing.”

Sims said the cats slowly started disappearing after the city started discussing a feral cat ordinance in November.  The proposed ordinance would require them to be trapped, neutered and released back into the wild, instead of euthenized.

Fort Worth Animal Control is investigating, but officers are also stumped about the mysterious absence.  “I’m sure the animals do relocate around Trinity Park and to some other areas, like the Botanic Gardens, but this is unusual not to see any,” said Assistant Director of Code Compliance Scott Hanlan.  “At this point we really don’t know what happened to the animals.”

Volunteers fear it’s no accident that the cats are all disappearing. Shelters that were built for them are also missing.  “I’m devastated we all are,” Sims said, “I’m having trouble sleeping at night going over and over and over in my mind what went on out here.”

There is another public hearing on the ordinace Thursday.

Volunteers believe controversy over the proposed ordinance many have lead to the cats’ disappearance.  They have set up a $1,000 reward for information, and have signs posted in the park.