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Trap, Neuter and Release
Should we TNR (Trap - Neuter - Release)? Some members of the mainland community have suggested we should use TNR as a means of controlling Kangaroo Island's feral cat problem. The method involves a large scale trapping programme, where all feral cats are trapped, desexed, released back into the wild and then "manage" them. The theory being that the neutered cats will defend their territories against any animals that missed the TNR program and the intact cats will eventually die out, with of course the neutered cats dying out also. The theory does sound good in principal, however there are some problems. Our committee have discussed these proposals at length and can't see any way of making such a method work on Kangaroo Island. The island is 145 km long by nearly 60 km wide, with 500 km of coastline and an area of more than 4,000 square kilometers. The estimated feral cat population is around 4,000, ie one per square km average density. With a typical trapping success of 3 cats per 100 trap nights, roughly 120,000 trap nights would be required to trap the entire population. There is a total of around 4,300 humans living on Kangaroo Island, so it would require every person on Kangaroo Island to attend around 30 trap nights. Traps cost around $100 each so to trap over a 30 day period, 4,000 traps would be needed - $400,000. In bulk they could be bought for less, but cat food is required to bait them, which would consume any bulk savings in purchase price. Logistically, it does seem rather impossible, and financially near impossible - where would the money come from? Then there is the rest... 1. Stress caused to the animal not accustomed to being handled by humans. 2. The cost of desexing 4,000 cats at $140 per female and $90 per male, and post-op care. Assume it can be done in bulk for $50 per cat - another $200,000. 3. The problems of releasing them back into the wild... Neutered cats are less able to defend territories against intact cats, they tend to be less aggressive. They can then resume killing wildlife They can then resume spreading sarco and toxo They still have a difficult life It is illegal The TNR proponents say we should "manage" them when reintroduced into the environment, but how do you do that? The only way we can see of restricting their diet to commercial cat food is to keep them caged, in which case they can't fend off any animals the TNR program would have missed. Consider also the cost, logisitics and health and safety outcomes related to caged feral cats! The TNR lobby claim that this is the only method that works, however the only published, peer-reviewed paper we have found on the subject states: "The spay/neuter campaigns brought about a general decrease in cat numbers but the percentage of cat immigration (due to abandonment and spontaneous arrival) is around 21 per cent. This suggests that all these efforts without an effective education of people to control the reproduction of house cats (as a prevention for abandonment) are a waste of money, time and energy." Management of feral domestic cats in the urban environment of Rome Natoli E, Maragliano L, Cariola G et al. Prev Vet Med 2006 • Update: since writing the above, another paper has been published in CSIRO's Wildlife Research which draws similar conclusions: Evaluation of euthanasia and trap-neuter-return (TNR) programs in managing free-roaming cat populations Paige M. Schmidt, Todd M. Swannack, Roel R. Lopez and Margaret R. Slater TNR was tried on the unowned cat population living along the beach front at West Beach, an Adelaide suburb. It was very expensive and has clearly not worked, for the same reasons the Rome experience failed. The cats are still there. • Update: most of the West Beach cats have been removed by volunteers, but some remain. Feral cats have been successfully eradicated from other islands: Macquarie Island and Marion Island, using a combination of methods including trapping, shooting, poisoning and dogs. Kangaroo Island is much larger and a different environment to virtually uninhabited sub-Antarctic Macquarie and Marion, and that sort of control could not be implemented here, but at least it can be said that feral cats can be eradicated from some islands. The KICCC state that TNR: is unlikely to work on Kangaroo Island would be a waste of time, money and resources would cause undue stress to the cats would not solve the problems cats cause would cause serious negative attitudes to Kangaroo Island from the rest of the world would be illegal If a TNR proponent would like to put together a sound proposal for how TNR could be made to work on Kangaroo Island, we would love to hear from them directly. An informative US website detailing problems with Trap-Neuter-Release.
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Home Page Wildlife at Risk Stock at Risk Pets at Risk People at Risk Who we are Future Plans News & Media Our Critics Resources Contact Us Cat Sightings Form Members Site Map

Kangaroo Island Cat Control Committee

Trap, Neuter and Release

Should we TNR (Trap - Neuter - Release)?

Some members of the mainland community have suggested we should use TNR as a means of controlling Kangaroo Island's feral cat problem.

The method involves a large scale trapping programme, where all feral cats are trapped, desexed, released back into the wild and then "manage" them. The theory being that the neutered cats will defend their territories against any animals that missed the TNR program and the intact cats will eventually die out, with of course the neutered cats dying out also. The theory does sound good in principal, however there are some problems. Our committee have discussed these proposals at length and can't see any way of making such a method work on Kangaroo Island.

The island is 145 km long by nearly 60 km wide, with 500 km of coastline and an area of more than 4,000 square kilometers. The estimated feral cat population is around 4,000, ie one per square km average density.

With a typical trapping success of 3 cats per 100 trap nights, roughly 120,000 trap nights would be required to trap the entire population. There is a total of around 4,300 humans living on Kangaroo Island, so it would require every person on Kangaroo Island to attend around 30 trap nights.

Traps cost around $100 each so to trap over a 30 day period, 4,000 traps would be needed - $400,000. In bulk they could be bought for less, but cat food is required to bait them, which would consume any bulk savings in purchase price.

Logistically, it does seem rather impossible, and financially near impossible - where would the money come from?

Then there is the rest...

1. Stress caused to the animal not accustomed to being handled by humans.

2. The cost of desexing 4,000 cats at $140 per female and $90 per male, and post-op care. Assume it can be done in bulk for $50 per cat - another $200,000.

3. The problems of releasing them back into the wild...

Neutered cats are less able to defend territories against intact cats, they tend to be less aggressive.
They can then resume killing wildlife
They can then resume spreading sarco and toxo
They still have a difficult life
It is illegal

The TNR proponents say we should "manage" them when reintroduced into the environment, but how do you do that? The only way we can see of restricting their diet to commercial cat food is to keep them caged, in which case they can't fend off any animals the TNR program would have missed. Consider also the cost, logisitics and health and safety outcomes related to caged feral cats!

The TNR lobby claim that this is the only method that works, however the only published, peer-reviewed paper we have found on the subject states:

"The spay/neuter campaigns brought about a general decrease in cat numbers but the percentage of cat immigration (due to abandonment and spontaneous arrival) is around 21 per cent. This suggests that all these efforts without an effective education of people to control the reproduction of house cats (as a prevention for abandonment) are a waste of money, time and energy."
Management of feral domestic cats in the urban environment of Rome
Natoli E, Maragliano L, Cariola G et al. Prev Vet Med 2006

• Update: since writing the above, another paper has been published in CSIRO's Wildlife Research which draws similar conclusions:
Evaluation of euthanasia and trap-neuter-return (TNR) programs in managing free-roaming cat populations
Paige M. Schmidt, Todd M. Swannack, Roel R. Lopez and Margaret R. Slater

TNR was tried on the unowned cat population living along the beach front at West Beach, an Adelaide suburb. It was very expensive and has clearly not worked, for the same reasons the Rome experience failed. The cats are still there.
• Update: most of the West Beach cats have been removed by volunteers, but some remain.

Feral cats have been successfully eradicated from other islands: Macquarie Island and Marion Island, using a combination of methods including trapping, shooting, poisoning and dogs. Kangaroo Island is much larger and a different environment to virtually uninhabited sub-Antarctic Macquarie and Marion, and that sort of control could not be implemented here, but at least it can be said that feral cats can be eradicated from some islands.

The KICCC state that TNR:

is unlikely to work on Kangaroo Island
would be a waste of time, money and resources
would cause undue stress to the cats
would not solve the problems cats cause
would cause serious negative attitudes to Kangaroo Island from the rest of the world
would be illegal

If a TNR proponent would like to put together a sound proposal for how TNR could be made to work on Kangaroo Island, we would love to hear from them directly.

An informative US website detailing problems with Trap-Neuter-Release.