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10 Types of Overpopulated Animals (Pictures)

Around the world, there are various animal species that have populations veering close to one and two billion. These overpopulated animals have gotten that way due to multiple regions, and some of them have grown to have negative impacts on other animals and their habitats. Multiple overpopulated species are kept as pets or used as livestock.

10 Overpopulated Animals

There are various overpopulated pet species in the world, and this guide will look at the top nine. The populations of these animals vary from a few million to over one billion. Multiple overpopulated animals have grown to such high numbers due to being bred as livestock or pets.

1. Cats

Cat stares at the sky | Image by Susann Mielke from Pixabay
  • Scientific name: Felis catus
  • Population: over 600 million
  • Range: worldwide

Cats can be found throughout the entire world, and are one of the most popular domesticated pets. While there is a huge number of pet cats, there are also large populations of homeless cats around the globe.

It is difficult to know the exact number since it is hard to know the exact population of feral cats. However, it is estimated there are more than 600 million cats in the world.

2. Pigs

pigs inside the cage with hay
Pigs inside the cage with hay | image by K-State Research and Extension via Flickr | CC BY 2.0
  • Scientific name: Sus
  • Population: more than 600 million
  • Range: various countries

Pigs are a common livestock animal bred and raised for meat. It is estimated that more than 600 million pigs are found around the globe.

They can be kept as pets as well, though the main purpose of these animals has become meat. Since pigs can eat plenty of old fruits and vegetables, they can also be helpful for composting.

3. Donkeys

donkey roaming in the grass field
Donkey roaming in the grass field | image by LHOON via Flickr | CC BY-SA 2.0
  • Scientific name: Equus asinus
  • Population: over 40 million
  • Range: Mexico, Africa, China, Asia

There are more than 40 million donkeys in the world, and these are well-known companion animals. They were domesticated thousands of years ago, and are beneficial in farms around the globe.

Donkeys can be good pets, and are helpful on farms to keep certain predators away from sheep, cows, and other livestock. These hardy animals can survive for a while with barely any water or food.

4. Goats

Goat eats fresh grass | Image by svklimkin from Pixabay
  • Scientific name: Capra Hircus
  • Population: around 900 million
  • Range: Americas, Europe, Africa, Asia

Goats are prevalent livestock animals but are also commonly found in the wild. These animals are found in multiple countries, including the Americas, Africa, Asia, and Europe. Goats are bred and raised for meat, as well as their hides.

Female goats are often raised for milk and cheese. They are sometimes kept as pets given their typical docile and gentle nature.

5. Sheep

group of sheep in the grass field
Group of sheep in the grass field | image by Katriona McCarthy via Flickr | CC BY 2.0
  • Scientific name: Ovis aries
  • Population: more than one billion
  • Range: multiple countries

Even though sheep are popular livestock animals, they have a reputation for being difficult to handle. They are often raised for wool, and need to be sheared often. Sheep can also fall victim to predators quite easily, and need to be enclosed, or guarded by another animal like a dog or donkey.

It is estimated over a billion sheep live in the world, but the total number is thought to be declining. These animals are raised as livestock in multiple countries.

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6. Cows

Cows roaming in the grass field
Cows roaming in the grass field | image by steve p2008 via Flickr | CC BY 2.0
  • Scientific name: Bos taurus
  • Population: over one billion
  • Range: worldwide

It is estimated there are more than one billion cows around the globe, and they are one of the most commonly raised livestock animals. Cows are raised for milk, meat, and their hide.

They are grazing animals known for chewing cud. In western regions, the population of cows is on a steady decline, though they are still one of the most overpopulated animals in the world.

7. Dog

A dog resting on hardwood floor.
Dog resting on hardwood floor. | image by llee_wu via Flickr | CC BY-ND 2.0
  • Scientific name: Canis lupus familiaris
  • Population: around 900 million
  • Range: worldwide

While there are over 400 million pet dogs found around the world, there are also millions of stray dogs. Europe, Russia, and North America have some of the highest populations of pet dogs.

Asia and Africa have some of the highest populations of stray dogs. There are hundreds of dog breeds in the world. These canines can be varying sizes and colorings.

8. Squirrels

Squirrel looking in his front direction | Image by JoeBreuer from Pixabay
  • Scientific name: Sciuridae
  • Population: over 2 billion
  • Range: worldwide

Squirrels are a common rodent that can be found in multiple countries around the globe. There are various species of squirrels, with the total number of squirrels in the world being somewhere over 2 billion.

These animals can be found in North America, Asia, China, Russia, Africa, and Europe. Squirrels are just as overpopulated as many domesticated animals, but they are not suited to be pets.

9. Rabbits

Rabbit rests on the grass Image by Pexels from Pixabay
  • Scientific name: Oryctolagus cuniculus
  • Population: over 700 billion
  • Range: various countries

Rabbits can be found in the wild, but have also become popular pets in multiple parts of the world. There are more than 700 million rabbits found around the globe, and in areas with high numbers of these rodents, they are known to damage gardens or crops.

Even though rabbits are overpopulated animals, certain species have seen a rapid decline, and some species have been listed as endangered.

10. White-tailed Deer

White-tailed Deer evadaing capture
White-tailed Deer evadaing capture | image by Jill Rogan via Flickr | CC BY 2.0
  • Scientific name: Odocoileus virginianus
  • Population: 30 million in the contiguous United States
  • Range: Southern Canada, most of the United States, and into Mexico

These animals are found in a variety of habitats including, but not limited to, woodlands and forested areas but also fields and brushland. White-tailed deer are the smallest type of deer in North America and also one of the most hunted animals in the United States. Despite that, they remain overpopulated in many states.

Because of that, governments allow a certain amount of hunting to be done in order to help control the population. Some states, like in New England, are having overpopulation problems because these animals have no natural predators int he wild and hunting rates are declining.


Overpopulated animals found around the world have gotten this way due to various reasons. Some were bred as pets and livestock, while others reached large populations without human interference.

In some cases, these populations can be harmful to the habitats they are found in, and can destroy crops or property. Sometimes overpopulated animals will negatively impact other animal species.

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