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Presentation to
AHA/CFA Feral Cat Conference

Karen Johnson, National Pet Alliance
August 10, 1996
Denver, CO

Good afternoon once again. Today, I would like to go over with you exactly what is known regarding owned and unowned cats from 4 demographic studies.

Four study comparison

The Massachusetts SPCA has just released a study which is actually a number of their studies which have been combined into one report. We will be discussing those studies along with the NPA reports in San Diego and Santa Clara Counties. For comparison, we will also be looking at a 1983 Las Vegas study.

These four studies were done in widely separated parts of the country, but for the most part have very similar numbers.

MSPCA, Massachusetts
NPA Studies of Santa Clara County and San Diego County, California
Dr. Nassar's Study, Las Vegas, Nevada

                 MSPCA   Santa Clara   San Diego   Las Vegas
                  1996       1993       1995         1983

% Cat Households   15%      19.40%       16%          24%  
% Dog Households   14%      18.60%       21%          49%  
%Cat & Dog 
Households          7%      10.80%         9%         n/a

No. of cats
per Household      1.6        1.7          1.7          1.6
No of Dogs
per household      1.2        1.3          1.4          1.5

Where Cats were obtained:

Stray 17% 32.50% 29.40% 24.50% Born at Home 3% 5.90% 10.10% 9.70% Given 47% 33.10% 31.10% 42.90% Shelter/HS/Animal Control/Rescue 12% 12.60% 8.90% 13.90% Pet Stores 8% 6 % 6.60% 4.50% Newspaper Ads 3% 1.40% 3.30% Breeders 3% 3.10% 4 % 4.60% Veterinarians 2% 1 % Other 4.90% 5.60% % of cats which died in past year 14.50% 14.50%

Owned cats which have been altered

Female - Spayed } 86.9% 82.8% 85.7% } 84% Male - Neutered } 85.9% 87.1% 78.9%

The percent of households which own cats ranges from 22-30%. The percent of households with dogs ranges from 21 to 49%. There are either 1.6 or 1.7 cats per household, and 1.2 to 1.5 dogs per household.

Most cats are obtained as either strays or gifts from someone. By combining the percentage of cats obtained as gifts and as strays, we find that 60-67% of all cats are obtained in this manner. Shelters provide 9-14% of cats.

Two studies show us that the average cat lives 7 years.

83-87% of female owned cats are altered.

The next chart shows us the known data on stray cats.

MSPCA, Massachusetts
NPA Studies of Santa Clara County and San Diego County, California
Dr. Nassar's Study, Las Vegas, Nevada

                 MSPCA   Santa Clara   San Diego   Las Vegas
                  1996       1993       1995         1983

#of stray cats
fed per household  3.7        3.4         2.6

Strays as a %
of total cat
population       42.10%     40.60%       35.70%

%of households
feeding strays    7%          10%         9%

%of fed strays
known to have 
had kittens       18%                     19%

Disposition of
stray kittens:

Adopted            31%                   }
Taken to Shelter   23%                   } 47.1%

Disappeared        23%                   }
Unknown            23%                   } 52.9%

Households which
have altered
stray cats          7%                      8.80%

% of cats:
Indoors only        38%        33.30%       37.20%
Indoor/Outdoor                 52.60%       45.40%
Outdoor only                   14.20%       17.40%


The number of cats claimed to be fed by, but not owned by, the respondents ranges from 2.6 to 3.7 cats per household feeding strays. 7-10% of all households are feeding stray cats. These strays, when added into the known owned cat population, represent between 36 and 42% of all known cats.

In two studies respondents were asked whether or not the strays they had been feeding had had kittens, and the disposition of the kittens. In the MSPCA study, 46% of the stray kittens had unknown fates, as did 53% of the San Diego stray kittens.

Only 7-9% of the households feeding strays had altered any of the strays.

One final note on owned cats--1/3 to 38% are kept as indoor only pets.

Are owned cats causing an overpopulation crisis?

Now, let us look at some of the data from various other sources, and what putting all this data together can mean Are Owned Cats Causing An Overpopulation Crisis?"

3 studies plus the San Diego study show 16-20% of owned cats have a litter prior to being altered. The primary reason for the litters are what we like to call the "Oops factor."

4 studies show us 86-91% of owned cats are altered.

Mortality is 7 years for owned cats, 3 years for unowned cats, and only 1/3 of feral kittens are still alive at age 1 year.

Although cats can have litters of up to 8 at a time, the average litter is 4.25 kittens, 2.1 times per year. 1/3 of the newborn kittens will either be stillborn, or die shortly after birth.

The ratio of sexes in owned cats is 50/50 initially, and by the time the cats are ten years old, the ratio is 70% female, 30% male. In unowned cats, we find the opposite. There are approximately 35% females, and 65% males.

Opinion is that there is very high mortality among the queens during pregnancy and delivery.

Assume 1000 owned vs unowned cats

Next, look at this chart. We are going to take all of the data from our various sources, and put it together to show what the actual reproduction of owned and unowned cats should be. On the owned cat side, this would be the least amount of kittens expected, and on the unowned side, this would be the worst case scenario.

Assuming 1000 owned cats, half of which are female, and 16% having a litter prior to being altered, and that 1/3 of the kittens die, we find only 31 live kittens born from a population of 1000 owned cats. But, we need 143 to replace those adults that die every year.

Assuming only 35% of the stray cats are female, and that 97% are capable of reproduction, out of our 1000 hypothetical stray cats, 1938 kittens will be born per year. Some of these kittens will be adopted into the owned cat population, the rest will be surplus.

Owned cats only produce 22% of the owned kittens necessary to maintain the owned cat population at zero population growth. However, on the stray cat side, not only are the strays producing more kittens than needed to sustain their population, they are also providing the balance of the kittens needed on the owned cat side. Of course, the more human intervention there is by altering the stray cats, the fewer kittens will be born.

San Diego trap/alter/release program

I touched yesterday on data from the Feral Cat Coalition in San Diego. This is the actual report. Stray cat intakes were increasing about 10% per year prior to the base year of 1991-92, where it peaked at 19,077 cats. After two years, only 12,446 cats were handled--a drop of 35%. Euthanasias plunged 40%.

72% of the stray cats were either in heat, pregnant or had recently had kittens. This is at least 3 1/2 times the rate of pregnancy found in owned cats (16-20% have a litter prior to altering).


What are the alternatives to dealing with stray cats?

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

We can trap/test/vaccinate/alter/release at a cost of approximately $70. Or, we can take them to the shelter for a 3 day stay, euthanasia and disposal at $70. Or, we can handle 3200 offspring over the next 12 years for $224,000.


For those forward thinking areas who recognize that it is cheaper to fix a cat than deal with the kittens, we have such things as voucher programs. In San Jose, the city provided $150,000 to alter any cat, owned or unowned.

Veterinarians who participated in the program were reimbursed $25 for females, and $15 for males. The cats which had more extensive surgery were altered at a higher price. Pregnancy, undescended testicles, in heat, etc., all qualified for a higher reimbursement. The overall cost has been $23.77 per cat.

Where do we go from here

We know that most owned cats are altered, and that most unowned/free-roaming cats are not, and that the majority of kittens necessary to replace the owned cats who die naturally are coming from the stray population. What happens when all the strays are fixed?

First, the kitten population drys up to a minimum because there are few reproducing cats, owned or unowned. Imagine this--to get a kitten, one must pay top dollar to a breeder of random-bred cats! In our life time? Maybe not.

What about the rodent population? What will happen to all the rodents that cats are currently eating? What other group of animals or birds will have to increase their population to keep up with the rodents, and will a surge in this population be acceptable? If stray cats are truly eating birds at the levels which have been estimated, what will happen to the bird population if there are no feral cats reproducing? Will there be too many birds for the resources available? (Will we have to start a permit program for feeding birds?).

Before we can say that having no free roaming stray cats is the ideal, we must consider these other issues.

Trap/Alter/Release vs. Trap/Kill

I want to show you 2 final graphs which a group of us have been working on-- Bob Plumb, a retired physicist in Paradise, CA, Rich Avanzino of the SFSPCA, and I, along with Ed Berry who has designed the program which produces these charts.

What we have is a program which will tell us what happens when the various variables regarding birth/reproduction/mortality are plugged in. This is a program which will be available for any community to plug in their own specific numbers and parameters, so that they can determine what needs to be done to handle their stray cat population--and how much it will cost.

Say we have a population of 1000 stray cats, and we are trying to determine if it is more cost effective to trap/alter/release , or to trap/kill to maintain the population at no more than 1000 cats. (Show spay chart). In this chart, we are going to have several types of cats--males, females, adolescents, and altered females. We are assuming a 3 year life span, 4.25 kittens born 2.1 times per year, 2.85 surviving kittens per litter, and 350 females.

In the population vs test year window of this chart, the top line is the dark blue, which shows the number of remaining cats in the colony over a 4 1/2 year span. You will note it drops off over time.

[Chart One]

The green line, second from the bottom, shows the number of spays which must be done per year to maintain the colony size. It starts at 247 initial spays, and thereafter, only 38 per year need to be done. At $70 per cat (including testing and vaccination) the initial cost for the medical work is $17,306. After that, it costs only $2,660 per year.

Contrast this to our other chart which shows what the costs are to manage 1000 strays by trap and kill.

[Chart Two]

The top red line is the number of births per year. The second line is the blue line showing that we want no more than 1000 cats. The third line tells us how many cats must be killed each year to maintain the population, over and above the number which will die from other causes. The bottom teal line tells us how many unspayed females there are. The initial cost to kill these cats is jut under $80,000, and thereafter remains at just over $60,000. per year.


All of our research and data gathered to date, shows one thing only--the solution to "too many stray cats are entering the shelter" can only be to trap/alter/release as many stray cats as quickly as possible. This is the most cost effective method in the long run.

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