O4W Cat Project
Atlanta Community Cats
What is TNR (Trap-Neuter-Return)?
TNR is the humane way to reduce feral cat overpopulation and was first introduced during the 1950s in Britain (more..)
It is how Fulton County Animal Control/LifeLine and all other "no kill" cities keep cat populations under control. The following is excerpted from the Humane Society of the United States material. At the base of this page are links to additional excellent TNR resources.

The TNR approach involves trapping the all cats in a feral colony, having them neutered, marked for identification and vaccinated for rabies, and returning the truely feral (cats unadapted to humans) to their original territory.

A caretaker then provides regular food and shelter and monitors the colony over time for newcomers and any potential problems that may arise. Ideally, all the cats in the colony will be caught and fixed and every effort should be made to do so, even if they can’t all be trapped at once. Caretaking a feral colony is made much easier when the neutering rate is 100 percent. Otherwise, that one female you didn’t get may keep having litters of kittens. Still, getting most of the adults fixed will at least temporarily stabilize and improve the situation.

Features of TNR

Rehoming Kittens and Friendly Cats

Whenever possible, kittens young enough to be easily socialized are removed from the colony along with friendly adults who are clearly former domestics and can be re-homed. Removing adoptable cats immediately reduces the size of the feral population (a primary goal of TNR) and gives the removed cats a chance at longer, safer lives. That said, if foster resources are not available, the TNR of the colony should not be delayed.

Neutered Cats are marked for future ID by Eartipping (see photos at right)

The minimum veterinary intervention upon capture includes spay/neuter, “eartipping” and rabies vaccinations. Eartipping is a procedure where a 1/4 inch off the tip of the left ear is removed in a straight line cut. It is the only reliable method known for identifying a neutered feral and is used globally.


Following surgery and a recovery period lasting usually two to three days, the ferals are returned to their territory. They must be brought back to the location where they were trapped and not released elsewhere – ferals are extremely tied to their surroundings and will flee in search of familiar surroundings if placed somewhere new without a proper relocation effort having been made.


The cats will continuously need food and shelter and should be provided these basic necessities in as consistent a manner as possible. Moreover, many things will happen over the years of the cats’ lives, such as new unaltered cats occasionally showing up, injuries or other health issues, conflicts with neighborhood residents and the like. When a caretaker is present to address these matters, the cats are more likely to lead a healthier and safer life than if they are left on their own.

A caretaker who watches for new cats will also help sustain the gradual reduction in the colony’s size over time through attrition.

Advantages of TNR

Colony Level Trap-Neuter-Return has many benefits when all or almost all of the cats in a colony are neutered:

  • Population stabilization - The size of the colony stabilizes as new litters are either eliminated or greatly reduced in number. Gradually, if newborns or newly arrived friendly strays are promptly removed from the colony as they appear, the number of cats will decline over time.
  • Noise reduction - A common complaint about feral cats is their high-pitched screeching in the middle of the night, which can disturb the sleep of an entire residential block. Most of this noise is the result of mating or fighting – behaviors which are eliminated or greatly lessened after neutering. Not that you won’t hear a good snarl once in a while, but not to the point where it becomes a constant nuisance.
  • Foul odors reduced - The noxious odor often associated with the presence of feral cats in an area is caused primarily by unaltered males spraying to mark their territory. Testosterone mixed in the urine is responsible for the powerful smell. Neutering stops the cat’s production of testosterone and, a few weeks after the surgery, any remaining testosterone has cycled out of the cat’s system and the odor is eliminated. In my experience, most male cats stop spraying completely after they’re altered, but even if they don’t, the “I can’t even use my own backyard” smell is gone.
  • Less visibility – Once mating behavior is eliminated, the cats tend to roam much less and stick closer to home base where food and shelter is supplied. As a result, they become a less visible presence in the area and are less likely to sustain fatal accidents with cars.
  • New cats are kept out – Feral cats tend to resist the intrusion of new cats into their territory. The degree to which they keep out newcomers is a function of the size of their food supply and territory. If they have a small territory and are fed only as much as they need, colony cats are highly motivated to guard their small space and limited food supply from newcomers. On the other extreme, if only a few cats inhabit a large space and are provided unlimited food, they may be more willing to allow new cats to join them.
  • Rodent control – Cats deter rodents, more by their scent than by hunting. Feral cats’ best friends are often the superintendents of buildings or managers of warehouses because these people know the choice is cats or rats and prefer the former. Typically, someone will bring a cat or two into a rodent-infested situation in to alleviate the problem. However, new problems arise when the cats proliferate. With TNR, the cats get to stay, the nuisance problems from feline overpopulation are eliminated and rodent control is maintained.
  • Improved community relations - When a feral cat colony is out of control, with litters of kittens continually recurring and noise and odor a real complaint, neighborhood residents often become hostile towards both the cats and anyone they believe is helping perpetuate the situation, such as feeders. When TNR is implemented and its advantages realized, the caretaker becomes an asset to the community instead of an enemy and the cats are better tolerated.
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Why has Trap/Neuter/Return of feral cats become the only legal means of controling wild cat populations in Atlanta?

It is illegal for extermination companies to interact with domestic animals. Perhaps the greatest advantage of TNR when it comes to controlling the population growth of feral cats is that, in most instances, all other known methods have historically failed. Removing feral cats "completely" as a means of solving the problems associated with them certainly has the appeal of simplicity. What would stop overpopulation and nuisance complaints faster than just taking away all the cats? But while in theory this may sound plausible, in reality removing feral cats almost never works to eliminate their presence.
Here are 5 reasons why TNR works:

1-The vacuum effect

Feral cat colonies spring up in certain locations because the habitat is suitable for their survival. If shelter and food adequate for at least their bare subsistence was not available, the cats would not be there. A feral cat colony "holds" territory that other cats will move into if vacated, called the “vacuum effect”.

This “vacuum effect” was first observed by wildlife biologist Roger Tabor in his extensive studies of London street cats, recorded in “The Wild Life of Domestic Cats.” The phenomenon of new cats moving in can happen very quickly.

I was once involved in the spay/neuter of a 35 cat colony that lived in a bungalow community. On the day of surgery, when all the colony cats were being fixed, new cats from adjacent blocks started showing up, tentatively exploring the vacated grounds. They left when the colony cats were released a few days later.

2-Just trapping and removing causes more cats, not less cats

Animal control officers or private property owners rarely have the time, resources, commitment or knowledge to successfully trap and remove 100 percent of a colony. Instead, trap and remove attempts typically involve laying out a number of traps, waiting a few hours at most, then carting away whoever was caught.

Trapping and Removing ALL the cats in a colony requires patience, persistence, time and money: some cats are almost always left behind. These remaining cats now have less competition for the food and shelter provided by the habitat. As a result, a higher percentage of their kittens are likely to survive than when the colony was fully inhabited. This “overbreeding” continues until the colony again reaches its natural population cap, which is the number of cats the habitat’s available food and shelter can support.

3- Monitoring of abandoned domestic cats

Feral cat colonies originate with lost or abandoned and sexually intact domestic cats. Abandonment of cats is unfortunately an ongoing problem which isn’t likely to end any time soon. Many abandoned cats were dumped because they reached sexual maturity and began displaying the problem behavior associated with unneutered cats, including spraying to mark territory or yowling. These cats wander until they either die or find a suitable habitat where they can survive.

An advantage of TNR is the presence of a caretaker to watch for newly arrived cats and either remove them for adoptive placement or at least ensure they get neutered and don’t reproduce.

4- Volunteer Caretakers

The caretaker(s) know how many cats there are, their habits, their hideouts, their feeding pattern. The caretaker is a willing and able population control worker and whose main concern is having all the cats safely eartipped so there are no kittens to worry about.

5- Volunteer caretakers are ESSENTIAL and make it possible to humanely control natural outdoor cat populations

Few municipalities, especially larger urban ones, can devote the manpower needed to TNR all the feral cats living in the community. For example, in New York City, there are at least tens of thousands of feral cats by even the most conservative estimates, and fourteen full-time animal control officers. Even if every one of them devoted all their working hours to TNR feral cats, it would have little effect.

Even in smaller communities with one or two animal control officers and perhaps a couple of hundred feral cats, it’s not realistic to expect these officers to be able to devote the time and effort required to TNR enough cats to get ahead of the reproductive curve.


TNR works! Links To More TNR Details...

Common Sense For Cats

Humane Society of the United States: Feral Cats

Alley Cat Allies: Conduct Trap-Neuter-Return




Until one has loved an animal, a part of one’s soul remains unawakened.
― Anatole France