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IMON receives a lot of requests for removing cats from areas.  Here is a good write up on why it is not a good idea.   It’s called the vacuum effect.   


Removing cats from an area by killing or relocating them is not only cruel-it's pointless. Animal control agencies and city governments have blindly perpetuated this futile approach for decades. But scientific research, years of failed attempts, and evidence from animal control personnel prove that catch and kill or removing doesn't permanently clear an area of cats.

Scientific evidence indicates that removing feral cat populations only opens up the habitat to an influx of new cats, either from neighboring territories or born from survivors. Each time cats are removed, the population will rebound to higher numbers through a natural phenomenon known as the "vacuum effect," drawing the community into a costly, endless cycle of trapping and killing.  The vacuum effect is a phenomenon scientifically recognized worldwide, across all types of animal species.

Well-documented among biologists, the vacuum effect describes what happens when even a portion of an animal population is permanently removed from its home range. Sooner or later, the empty habitat attracts other members of the species from neighboring areas, who move in to take advantage of the same resources that attracted the first group (like shelter and food). Killing or removing the original population does nothing to eliminate these resources; it only creates a "vacuum" that will inevitably draw in other animals living nearby.


Scientific research has observed the vacuum effect across many species-herbivores, carnivores, and omnivores. When studying mountain lions, for example, one researcher noted, "When you remove resident lions that have established home ranges you create a void." He continues, "Other resident lions that have home ranges that may overlap the individual you removed now Find that territory empty. This allows them to expand their range, as well as create openings for transient lions to establish a new home range."


Simply put, when mountain lions are removed from their habitat, other mountain lions move in. This behavior has also been documented in possums, badgers, and raccoons.  A habitat will support a population of a certain size. No matter how many animals are removed, if the resources remain, the population will eventually recover or grow larger. Any cats remaining after a catch and kill or catch and remove effort will produce more kittens and at a higher survival rate, filling the habitat to above capacity. As one study found, "populations greatly reduced by culling are likely to rebound quickly." Over time, the number of cats in an area where a feral cat colony has been killed or relocated will simply recover and in greater numbers.

If you are having problems with a feral cat colony, please contact us for solutions that will change the bad behavior of the feral cat colony.  Unmanaged cat colonies are known for fighting, noise, destruction of property, and multiple other issues that can be corrected without removing the colony and getting a larger colony with worse issues move into its place.


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