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What Is Trap-Neuter-Return?

Trap-Neuter-Return is the only humane and effective approach to community cat populations. Here are the three basic steps to this lifesaving process:

1. Trap: Humanely trap all the cats in a colony. A colony is a group of cats living outdoors together.

2. Neuter (or spay): Take the cats in their traps to a veterinarian or clinic to be neutered, vaccinated, and eartipped (the universal symbol of a neutered and vaccinated cat. Learn more at

3. Return: After the cats recover, return them to their outdoor home where they were trapped.

Watch videos of cats being returned and how to do Trap-Neuter-Return at

To view our TNR Program Information, and how our program works, click HERE

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Why Trapping and bringing cars into the shelter doesn't work. 

Have you heard of the vacuum effect? 

The Vacuum Effect has been documented worldwide in many species. Animal control’s traditional approach has been to have community members trap and then bring in community cats to the shelter. While this may temporarily reduce the number of community cats in a given area, it is ultimately counterproductive, as the population of cats rebounds. Due to the Vacuum Effect, untrapped cats continue to breed, and other cats move into the newly available territory.


The Vacuum Effect occurs when a portion of an animal population is permanently removed from their home range. The result is a temporary dip in population levels. The initial population lived in that location because there were resources such as shelter, food, and water. Once emptied, this still resource-rich habitat inevitably attracts other members of the same species from neighboring areas. They move in to use the same resources that sustained the first group. Both the new individuals and any remaining members of the original population then reproduce. What’s more, they reproduce at higher rates to fill the habitat and take advantage of the available resources.

Before long, the area fills back up to capacity again, as if the animals were never removed at all.

The Vacuum Effect occurs across many species, including foxes, mice, coyotes, voles, possums, and badgers. Of course, it also occurs for cats.

Colonies that are involved in TNR diminish in size over time. TNR quickly stabilizes feral cat populations by instantly ending reproduction and by removing socialized cats from the colony.

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The shelter received a grant from California for All Animals to support and expand our TNR program. The shelter has created two sub-programs to offer spay/neuter services for feral cats for FREE.

  1. Low-income caregivers: This program is for City of Hayward residents who need help spaying or neutering community cats that they feed on their property. We will provide up to 5 FREE surgeries per household through this grant.

  2. Neighborhood TNR: This program is for City of Hayward residents who would like to help reduce the cat population in their neighborhood through TNR. Free roaming community/feral cats in their neighborhood would be trapped by members of that neighborhood for the purpose of spay or neuter and then be released back into the neighborhood they call home. Up to 10 FREE surgeries per neighborhood are available through this grant.

Click here for more information about and to see if you qualify for FREE TNR through one of the grant programs.

If you are interested in becoming a TNR volunteer, please email the shelter at:

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Additional information and resources:

Alley Cat Allies

Fix our ferals


Kitten Lady's video:

"If you see cats outside...WATCH THIS

Kitten Lady's video:

"Why are some cats FERAL?"

Kitten Lady's video:

"Trap-Neuter-Return FAQ!


Feral Cat Spaying & Neutering

Humane Society of Silicon Valley*

(408) 262-2133

$50 for spay/neuter

*Due to COVID-19 HSSV is temporarily closed to the public for Spay/Neuter Services. Please check directly with HSSV for updates. 

Nine Lives Foundation, Redwood City

(650) 368-1365

$50 (spay) $40 (neuter)

Animal Fix Clinic

(510) 215-9300

$45 for TNR or free-roaming

$85 for pet cats

East Bay SPCA

(510) 639-7387

(925) 479-9674

$40 for TNR or free-roaming

$75 - $100 for pet cats

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