An "Overpopulation" Problem? Maybe, but not with dogs

by Cadie Pruss

“The fact is the dog-breeding industry has led to a huge overpopulation of dogs in this country”- 2008 James E. Casorio, Jr. Pennsylvania state representative for the 56th District in Westmoreland County

Have dogs reached the point of Overpopulation in this country? No. “Overpopulation” occurs when a species has grown beyond its carrying capacity. Carrying capacity is the maximum population that can be sustained without depleting the resources necessary to maintain the population. When carrying capacity has been exceeded, overpopulation of that species has occurred and the subsequent changes in the environment begin to limit the population, thus causing a reduction in the population.

Some may argue that the mere fact that animals in shelters are put down is a sure sign that overpopulation has occurred, but that test dose not meet the accepted biological definition of Overpopulation. There are plenty of resources such as food, water and shelter, (the only true necessities of life) to sustain the current population of all dogs, including a feral population of Carolina Dogs living in remote areas of South Carolina and Georgia.

If an Overpopulation problem was occurring nationwide, feral populations such as the Carolina Dogs would be subject to pressure from domestic dogs. This pressure would include fighting for resources such as food and suitable shelter. With increased pressures on limited resources, the Carolina Dog, and all domestic dogs vying for the resources would suffer from an increase in disease outbreaks. This is not occurring and to date, the Carolina Dog has not hybridized with other domestic dogs, indicating that this population has remained isolated. In an Overpopulation scenario, no contiguous population would remain uneffected.

Money is not one of the true necessities of life, but it seems that there is no shortage of that either when it comes to dogs in America. According to WikiAnswers, the average American dog owner spends $2000 per year on their dog, and charitable organizations working to “save unwanted dogs” are raking in donations. According to statistics from the American Pet Products Manufacturers Association (APPMA), pet ownership is at an all time high with 63% of all households owning a pet (“pets” refer to more than just dogs in the APPMA statistics). Nope, there is no shortage of the “resource” money when it comes to dogs.

But seriously, lets talk about Overpopulation. According to the U.S. Census Bureau, population division, as of December 1, 2008 there were 6,740,604,309 people in the world with 305,786,924 of those people in the United States. The APPMA estimates there are 73,000,000 dogs in the United States, which is only 1 dog for every 4 people in this country. According to the National Center for Health Statistics, the average life expectancy in the United States is currently 77.8 years. The average life expectancy of a dog living in North America is 12.8 years. One person’s life span is equal to the life span of 6 dogs.

The average American (over the age of 4) needs about 2,350 calories per day. To determine the number of calories a dog needs, they are generally grouped into 3 categories of small, medium and large. In general, a small dog needs about 40 calories per pound of body weight per day, while a medium sized dog needs about 30 calories per pound per day and a large dog only needs about 20 calories per pound per day. So using a thirty-pound dog (considered “medium” size) as an example, 30 calories/ pound/ day x 30 pound dog= 900 calories a day, so the average thirty pound dog needs about 900 calories per day. Strictly from a calorie consumption standpoint, each day 1 person = 6 small dogs, 3 medium dogs or 2 large dogs. Over a lifetime, 1 person = 35 small dogs, 16 medium dogs, or 13 large dogs. According to the Center For Science in The Public Interest, food is still considered abundant in the United States. The Center For Science in The Public Interest claims there are 3,800 calories available in the food supply for each person each day. That is an extra 1,450 calories per day, per person (or an extra 1.6 medium dogs, per person). The amount of “available calories” we just calculated didn’t even take into account the food sources that are “available” to those 73 million dogs, because what they are fed is generally not considered fit for human consumption. So, if we added the 1.6 “extra” dogs/per person (305,786,924 x 1.6= 489259078.4) and then add the existing 73 million dogs, we get 35,715,912,723,200,000- and this is the number of dogs we have enough calories to feed in the U.S. currently. That is a lot of dogs. It appears that in the U.S., food is not the dog limiting resource.

Average lifespan in years: Person 77.8 Dog 12.8 1 person = ? medium size Dogs 6
Calorie needs per day: Person 2,350 Dog 900 1 person = ? medium size Dogs 35
Water use in gallons per day: Person 123 Dog 0.25 1 person = ? medium size Dogs 492
trash produced in pounds per day: Person 4.6 Dog 0 1 person = ? medium size Dogs 4.6
Dogs don’t need to live in houses. The Carolina Dogs and a thriving population of Coyotes and foxes prove that dogs can do just fine with the shelter that Nature provides, but if we feel that dogs do need to live in a human home, then according to the U.S. Census Bureau American Housing Survey in 2001, there are 119,117,000 housing units in the United States. Although this number has increased since 2001, it won’t match the thirty-five quadrillion, seven hundred fifteen trillion, nine hundred twelve billion, seven hundred twenty-three million, two hundred thousand dogs we can caloricly care for in this country- so our dog carrying capacity has been reduced by the availability of shelter, but even still, 119,117,000 homes is still greater than the 73,000,000 dogs in this country. So shelter is not the limiting factor so far.

The average American uses about 123 gallons of water each day! People use water for more than just drinking, people shower (15-30 gallons), wash the dishes (9-12 gallons if you use a dishwasher, 20 gallons if you wash them by hand), flush the toilet (5-7 gallons) and the list of uses goes on and on. Dogs typically drink about 1 quart of water a day (depending on size of the dog of course). So once again we convert people to dogs, and we get 1 person equals 492 dogs. Water is not the limiting factor either.

An outbreak of Zoonotic Diseases from dogs to humans has not occurred in recent U.S. history, nor has a dog-dog outbreak occurred. Disease outbreaks are typical in populations reaching carrying capacity. It is one of natures ways of limiting populations. Clearly Overpopulation of dogs is not occurring in this country. How ever, people may need to begin to limit the human population expansion.

In 2002 the National Wildlife Federation stated the population of the United States was 282,000,000 and that equated to 31 people per square Kilometer (sq. Km) (or 50 people per square mile). According to consumption figures distributed by the National Wildlife Federation in that year, for every 100 humans in the United States, there are 489 cars. Americans consumed 1,688 liters of motor gasoline per capita each year. The average American household produces 100 pounds of trash each week and our demand for wood and forest products has resulted in the loss of 96% of our country’s original forests. Dogs don’t buy cars, use gas, produce trash, or use wood and forest products. Even 100 dogs don’t equal the resource consumption of 1 American. People might do all of these things FOR their dog, but feral dogs do not do any of those things themselves.

The land area of the United States is 9,158,960 sq. Km (or 5691,114sq. miles), so in 6 short years the American population expanded 23,786,924 people, while the United States land area expanded 0, and we now have 33 people per sq. Km (or 54 people per sq. mile).. At this rate, American’s may be experiencing an Overpopulation problem- but not dogs.



Sources:
National Wildlife Federation, Population & Consumption https://secure.nwf.org/globalwarming/pdfs/popandconsumption2002.pdf

Center For Science in The Public Interest Nutrition Policy- http://www.cspinet.org/nutritionpolicy/food_advertising.html

ABC News: What’s Your Dog’s Eating Habits http://abcnews.go.com/GMA/Story?id=1905511&page=4

Pimentel, D. et. al, 1999 Will Limits Of The Earth’s Resources Control Human Numbers?
http://www.dieoff.org/page174.pdf

Food and Agriculture Organizations of the United Nations
http://www.fao.org/es/ess/faostat/foodsecurity/index_en.htm

Decline in Pet numbers blamed on shrinking backyards
http://www.vetclick.com/news/view_article.php?ArticleId=272

Netscape Home & Living- It’s Reigning Cats and Dogs: How many pets are in the U.S.?
http://webcenters.netscape.compuserve.com/homerealestate/feature.jsp?story=rainingcatsanddogs
US Census Bureau American Housing Survey
http://www.census.gov/hhes/www/housing/ahs/ahsfaq.html

Science Fact Finder- How much Water Does An Average Person Use Each Day
http://www.enotes.com/science-fact-finder/energy/how-much-water-does-an-average-person-use-each-day

Yukon Quest Sled Dogs
http://www.yukonquest.com/site/water-water-everywhere/