A Report on Trap/Alter/Release Programs

(c) 1995 Karen Johnson
National Pet Alliance, PO Box 53385, San Jose, CA 95153, 408-363-0700

The most common preferred method put forth by animal control organizations for control of cats has traditionally been to capture and euthanize feral/unowned cats. Others, who refer to this means of control as the ``trap and kill'' method, consider it inhumane and objectionable on several fronts. A major factor has been that it has been shown that as soon as a cat is removed, a new one will move in to take over the food source[Ref1]. Additionally, unless the cat is making an unusual pest out of itself, why should a wild animal be euthanized simply for not having a human address?

After a six-year study and daily observation of a feral cat colony, it has been documented that stray female cats start cycling when they are 4-6.9 months old[Ref2], or as soon as the days are long enough. January and February are the start of the kitten season, with the litters born in March and April. These cats have an average of 2.1 litters per year of 4.25 kittens[Ref3]. 42% of the kittens will die by the age of two months of natural causes[Ref4]. Many more will end up at the shelter. Those who escape early death and the shelter go on to be prolific bearers of kittens over their short lifespan of approximately three years[Ref5].

Taking the mortality into account, along with birth and death rates, the average stray female will have 5.25 litters in her lifetime, encompassing 22.3 kittens. At age two months there should be 12.9 survivors, roughly six females and seven males (at maturity, roughly 2/3 of the stray cat population is male[Ref6], due to the high mortality of females during first pregnancy and birth), which will decrease to four females over time. These six females will go on to have their 22 surviving kittens each. Realistically, over 12 years, one unspayed female, with all her unspayed female offspring, reasonably can be expected to be responsible for over 3200 kittens if there is no human intervention.

Some continue to advocate the trap and kill eradication approach. However, if eradication programs really worked, we wouldn't be faced with so many stray cats and their offspring at the shelters. Cats are territorial. They don't allow other cats into their territory to steal their food. Altered cats will stand their ground and guard their food source, will not have kittens, and will die in a few years. Remove the cat(s) from the habitat without changing the habitat and another cat will move in.

The Humane Society of Santa Clara Valley estimates over 50% of their stray cats euthanized are either wild, or their unweaned offspring. Once the offspring of these feral cats are over about six months of age, it is nearly impossible to socialize them to the degree necessary to be placed as house pets. An unsocialized cat is an unadoptable cat. The Cities and Counties pay for the handling of these stray cats and their offspring. Reducing the number of kittens born to these cats would substantially reduce the number of cat euthanasias at the shelter, thereby reducing the costs born by the taxpayers to handle and kill stray cats which cannot be socialized.

Unowned/wild cats are routinely euthanized at shelters. Even though the kittens can often be socialized for placement, it does take a minimum of two to three weeks of intensive work. Shelters simply don't have the time, personnel or cage space to socialize the kittens. Many do not have foster care available for this work. The alternative, for the most part, is euthanasia.

Reproduction Intervention as an Alternative Approach

In 1989, Stanford University officials announced a plan to trap and kill approximately 500 stray cats living on campus. As a result, Stanford Cat Network was formed. SCN was able to present an alternative solution in which they would organize to trap, alter, release and manage the cats, to stop the progression of reproduction on campus. Because of their hard work, Stanford cats now have zero population growth as a result of diligent and on-going trapping and spay/neuter efforts, and the population is declining through natural attrition. Over 60 kittens were caught, socialized and adopted out during the first season. By 1994, only four kittens were found on campus. The campus population is now estimated at approximately 300 cats. Stanford's current cat population is healthy and well-cared for, and its maintenance involves students, staff, and faculty.

SCN has accomplished all of this without financial support from the University. SCN's successful five-year program with a very large cat population demonstrates that feral cat colonies can be managed and kept under control, and that a workable, viable alternative to a rush for extermination does exist.

In San Diego County, the non-profit Feral Cat Coalition has trapped, altered and released in excess of 3,100 cats over the past two years. In addition to these cats, which were over five months of age at the time of altering, an unknown number of kittens were also trapped, socialized and adopted into new homes.

Prior to this project, San Diego County Animal Management Information System reported an increase of roughly 10% per year in the number of cats handled by San Diego Animal Control shelters from 1988 to 1992. The increase peaked at 13% from Fiscal Year (FY)91 to FY92, with a total of 19,077 cats handled. After just two years, with no other explanation for the drop, only 12,446 cats were handled--a drop of 35%. Instead of another 10% annual increase, euthanasias plunged 40% from 91-92 to 93-94.

San Diego Animal Control Cat Statistics 1988-1994

Year   Total   Claimed   Adopted   Euth.   Research   Other*
----   -----   -------   -------   -----   --------   ------
88-89  13929     202       2130    10976       7       614
89-90  15394     230       2224    12349       -       591
90-91  16849     238       2426    13561       7       617
91-92  19077     248       2577    15525       6       721
92-93  14143     180       2297    11121       -       545
93-94  12446     223       2386     9269       -       568

From 1988-91, the number of dogs handled did not increase, but dropped a total of 5.7%. A more dramatic 20% drop was reported from FY92 to FY94. Dog euthanasias then dropped 29.7%.

San Diego Animal Control Dog Statistics 1988-1994

Year   Total   Claimed   Adopted   Euth.   Research   Other*
----   -----   -------   -------   -----   --------   ------
88-89  24070    5147       4355    13313      526      729
89-90  24177    5213       4540    13215      324      885
90-91  22549    4749       4357    12155      320      968
91-92  22707    4847       4493    12216      233      918
92-93  19544    4342       4385     9791      239      787
93-94  18275    4014       4721     8592      159      789

*Other includes: return to wild, transfer to correct jurisdiction, wildlife rehab, stolen, escaped, DOA, died in kennel, died in truck, died at contract vet, misc.

Of the 3,153 cats trapped by the Feral Cat Coalition which were altered, 54% were female and 46% were male. Of the 1639 females spayed, the following characteristics were noted:

    453  Normal         28%
    691  In Heat        42%
    218  Pregnant       13%
    216  Lactating      13%
     61  Post Queening   4%
   ----                ----
   1639                100%

Only 3%, 86 cats total, were found to have been already altered. 17 cats were refused surgery for being under five months of age, or too ill. 18 cats died during surgery. 679 cats (22%) needed additional medical treatment--generally amoxicillin for infections, or ivomectin for mites or worming. Additionally, cleaning and suturing wounds and abscesses were very common.

72% of these stray female cats were either in heat, pregnant, or had recently had kittens. This is at least a three and a half times higher incidence of pregnancy than found among owned cats. Three studies have shown between 16-20% of owned cats have a litter prior to altering. A 1991 Massachusetts SPCA study found 20% of owned cats had a litter[Ref7], a Las Vegas Study reported 16% of owned cats reproduced[Ref8], and in the 1993 survey of Santa Clara County residents, 16% also verified that their cats had a litter prior to altering[Ref9].

Clearly, the project to trap, alter and release cats in San Diego County has had a dramatic effect on the number of cats handled and euthanized at their shelters, which even historical or nationwide downward trends cannot explain.

Santa Clara County Animal Control has estimated that the cost to handle a stray cat for the three required days in the shelter, plus euthanasia and disposal, is $70 per cat. There are still only three alternatives to handling the population of stray cats: 1) alter/release/management; 2) exterminate/euthanize; 3) ignore.

Let us now compare costs:

Test/Vaccinate/Alter = $52 on a low cost program
3 Day required stay at shelter = $70
Handle 3200 offspring = $224,000

41% of the known cat population in Santa Clara County is unowned[Ref10]. This equates to 168,463 cats which will, for the most part, be unaltered. Do we allow them to continue to breed, adding ever more cost to animal control budgets and taxpayer burden, or do we take the initiative to trap, alter and release them, reducing the number of fertile females to manageable levels?

Now, before the start of kitten season, is the time to start trapping the cats. Every female trapped now will reduce the number of kittens needed to be handled by animal control this summer by at least Two. Do we spend $52 now on the spay, or $140 to handle the two kittens estimated to survive this spring? There are volunteers in the community who care about cats. Animal agencies should aggressively take the lead in encouraging and enabling citizens to help out on this problem. Organization must be established within the community. This enables volunteers to know what to do. Provide the means for the medical treatment, and citizens will provide the services to trap the cats and take them to the veterinarians. But, for the best possible outcome, provide both for those areas with large colonies.

Funding for a program of this type can take many forms:

  1. Looking at the figures from San Diego, one can readily see that for a cost of (3153 cats X $52 per cat) $163,956, they have reduced the expenses at their shelter by at least 6500 cats, or $455,000, over a two year time span. This successful track record shows that in actuality no additional funds need be raised--the program will pay for itself through less shelter costs. The initial funding for altering could be taken from the shelter budget. (San Diego, however, did not pay for the veterinary services. All services were donated by veterinarians and others. Medical supplies were purchased through contributions to Feral Cat Coalition).
  2. For those who prefer not to gamble with the shelter budget, an alternative is to request the Board of Supervisors to allocate seed money for a trap/alter/release program, after showing them the future savings to the animal control budget. The City of San Jose found surplus funds in the Animal Licensing budget. Perhaps the County may also find such a surplus.
  3. Alternatively, if a restricted pet product surcharge was proposed in this county, for use only for trap/alter/release program seed money, and the surcharge would end as soon as the program was proving that the shelter costs for stray cats and kittens were decreasing, probably few in the pet community would have an objection. The decreased shelter costs would then more than fund the ongoing trap/alter/release efforts.
There may be those who prefer to continue the eradication method. The concerns put forth are usually centered around noise (cats fighting over territory or mating), smell (of spray), vector infestation, disease transmission or possible injury. The assumption of a quick and clean solution makes this avenue of population control especially attractive. Yet eradication programs are ineffective[Ref11]. While attractive from a theoretical and short-term perspective, eradication has proven to be an elusive goal[Ref12].

Following trap/alter/release programs, mating behavior and noise is eliminated. The male urine spray smell is eliminated. Disease transmission to humans is a negligible factor due to the few diseases which cats can pass to humans. Rabies is one. There were only two cat rabies cases found in 1993 in the entire state of California, out of a current population of some 13 million owned and stray cats. The risk is minimal. Vector problems should increase with removal of stray cats, until such time as an increase in other rodent predators takes the place of the missing cats. Most of us would probably prefer to have a small, healthy feral cat population, rather than a larger Norway rat and seagull population in habitats where those are the only options[Ref13].


We strongly recommend immediate issuance of vouchers for all unincorporated county residents to take their stray and ``loosely owned'' neighborhood cats in for free altering. The sooner the program begins, the sooner the reduction in shelter costs will occur. For the fastest method of notifying residents of the programs, perhaps a utility insert, or special mailing to residents could jump start the program fast enough to show reductions in shelter expense within 3-4 months.

We have estimated that due to death of owned cats, in excess of 17,000 kittens are needed annually in Santa Clara County just for replacement. These kittens will need to be altered. It would be ideal to develop the trap/alter/release program in such a way that the 17,000 owners of kittens which need altering, and who could otherwise afford to alter their cat, do not use the voucher funds to the detriment of the stray cat altering program.

86% of owned cats in Santa Clara County are altered[Ref14]. From San Diego we know 97% of stray cats are not altered. There is no doubt which cat population is causing the huge numbers of cat euthanasias at the shelter. It's time to get to work and start altering the stray cats now.


  1. Zaunbrecher, K., Smith, R., ``Neutering of Feral Cats as an Alternative to Eradication Programs''. Journal of American Veterinary Medical Association (JAVMA), Vol.203, No.3, August 1, 1993:449-452.
  2. Jochle, W., Jochle, M., ``Reproduction in a feral cat population and its control with a prolactin inhibitor''. 2nd International Symposium on Canine and Feline Reproduction, Belgium.
  3. Pedersen, N., Feline Husbandry. American Veterinary Publications, 1991:3-12.
  4. Berkeley, E.P., Maverick Cats. New England Press, 1982.
  5. Berkeley, E.P.
  6. Berkeley, E.P.
  7. Handy, F.L., ``Measuring your community's pet population, owner attitudes''. Shelter Sense, Vol.16, No.5, May 1993:3-12.
  8. Mosier, J.E., Williams, L.W., Nassar, R., ``Study of feline and canine populations in the Greater Las Vegas Area.'' Am. J. Vet. Res., Vol.45, No.2, 1984:282-7.
  9. Johnson, K., Lewellen, L., Lewellen, J., ``National Pet Alliance's Survey Report on Santa Clara County's Pet Population.'' The CFA Almanac, Jan. 1994.
  10. Johnson, K.
  11. Zaunbrecher, K.
  12. Holton, L., Manzoor, P., ``Managing and Controlling Feral Cat Populations''. Veterinary Forum, March 1993.
  13. Clifton Merritt, Editor, Animal People on AOL, Dec. 1, 1994, Pet Care-Animals and Society Board.
  14. Johnson, K.

Karen Johnson, KarenJ115@aol.com