Humans have co-existed with mammals for a long time. Mammals are important for the balance of the ecosystems in which they exist. However, they can also be very destructive causing damage to not only plants but also the birds, humans, and other mammals. Some of the 14 worst invasive mammal species include goats, rats, mice, red deer, and cats among others as summarized below.
14. Goats (Capra hircus)
Capra hircus, simply referred to as goats, survive in the harshest conditions. Although domesticated from the wild goats of Southwest Asia and Eastern Europe, goats have since spread across the globe as they are kept for their milk, meat, fur, etc. When given the opportunity, goats are one of the quickest domesticated animals to return to feral life. There are strong feral goat populations in Great Britain, Australia, New Zealand, and the Galapagos among others. Goats are herbivores that eat most plants within their environment. However, in the course of their feeding, the eating habits of the goats may result in an ecologically imbalanced environment.
13. Red Deer (Cervus elaphus)
Commonly referred to as the red deer, Cervus elaphus is native to Eurasia. However, with time it has spread to other parts of the world such as Australia, the Americas, and New Zealand. Red deers inhabit open grasslands, temperate rain forests, human-made clearings, and mountain ridges. They devour the plants within their surrounding such as the thick, moist grasses. Consequently, there is soil erosion and severe overgrazing. To control the red deer populations, humans are encouraged to engage in red deer hunting.
12. Feral Cats (Felis catus)
The feral cats, scientifically known as the Felis catus, are among the favorite pets reared by humans. Despite giving people company, they also help in preventing rats, mice, and snakes from invading homes. Notwithstanding these benefits, cats are among the worst invasive mammal species. Firstly, they are responsible for killing about 480 million birds annually. Some of the affected species of birds are the Okinawa woodpecker and seabirds. Besides, cats also spread diseases such as toxoplasmosis and rabies.
11. Mongoose (Herpestes javanicus)
Also called mongoose, Herpestes javanicus are native to South and Southeast Asia, more specifically Myanmar, India, Iran, and the Thai Malay peninsula.The species is now found in South America, the West Indies, parts of Europe such as Croatia, and islands such as Fiji and Hawaii. The mongoose may be used to control populations of rats. However, they endanger the existence of animals such as Hispaniola’s racer and Fiji’s barred-wing rail.
10. Crab-eating Macaque (Macaca fascicularis)
Scientifically known as Macaca fascicularis, the crab-eating macaque is native to South East Asia. They are considered invasive species in western New Guinea and Hong Kong. As they are opportunistic omnivores they create a threat to the biodiversity in the areas to which they are invasive as well as agricultural pests.
9. Mice (Mus musculus)
Besides human beings, Mus musculus, the scientific name for mice, are considered to be the most widely spread animal in the world. Native to South Asia they are now an invasive species worldwide. Mice are invasive in two ways. First, they eat human food reserves as well as dig up crops. Secondly, they carry pathogens such as salmonella and bubonic plague. Mice also prey on albatross chicks and are good at breeding. Interestingly, female mice give birth to between 30 and 60 litters every year. As a result, the mice population rises at a high rate. Consequently, the effect of the mice’s destruction also increases proportionately.
8. Short-tailed Weasels (Mustela erminea)
A native of North America and Eurasia, Mustela ermine is responsible for decimating many mammal and bird species. New Zealand’s baby kiwis are examples of animals that are at risk of extinction because of the weasels. Also called stoats or short-tailed weasels, these mammals are very intelligent. They are also excellent swimmers as well as swift animals. They can attack animals larger than themselves for food. They are often used to manage species of smaller invasive mammals such as rats.
7. Nutria (Myocastor coypus)
Myocastor coypus is the scientific name of a rodent called the nutria. The nutria is a semi-aquatic mammal that is native to South America. It resembles a rat, but has softer fur than the rat. Nutria are excellent burrowers that enjoy feeding on vegetation. However, they consume so much vegetation that they often wipe them out completely. Japan’s deepbodied bitterling fish and Libellula angelina dragonfly are endangered by the nutria. Furthermore, in Italy, these rodents have destroyed the water lilies responsible for the breeding of whiskered terns.
6. Rabbits (Oryctolagus cuniculus)
The Oryctolagus cuniculus are commonly referred to as rabbits. Besides their sweet meat and popularity as pets, rabbits are quite invasive. If their populations are not controlled, rabbits could single-handedly wipe out every bit of vegetation. Native to the Iberian Peninsula, these mammals have spread to other parts of the world such as the Americas, Africa, and Australia. They endanger vegetation through overgrazing and persistent burrowing.
5. Black Rats (Rattus rattus)
Native to India, the Rattus rattus is one of the most invasive mammals in the world. Also called black rats, Rattus rattus inhabit both homes and the wild. It is not surprising to find them living in woodlands and forests as well as in buildings. The rats destroy any edible thing including plants, clothes, seeds, and wood. They are responsible for the extinction of small mammals, birds, plant species, and reptiles among others. Rats also carry pathogens such as trichinosis, typhus, and toxoplasmosis. In most cases, households get rid of invasive rats by rearing cats.
4. Grey Squirrels (Sciurus carolinensis)
Native to eastern America, the Sciurus carolinensis has spread to Britain, South Africa, Italy, and Ireland today. Also called grey squirrels, they often feed on seeds, nuts, fungi, and fruits. However, whenever their supply of food runs out, they invade barks of trees such as sycamore and beech. Whenever the red and grey squirrels exist in the same habitat, the grey squirrels are likely to out-compete the red squirrels. Besides destroying barks of trees, the grey squirrels also carry a virus known as parapoxvirus. This virus causes a deadly disease in red squirrels.
3. Wild Boar (Sus scrofa)
Sus scrofa is the scientific name for pigs also known as boars, wild hogs, or feral hogs. Native to Eurasia, North Africa, and the Greater Sunda Islands, they are invasive worldwide. These pigs are known to be very destructive. In Texas alone, the damage caused by pigs is estimated at $400 million every year. Pigs carry foot-and-mouth disease and other diseases that affect animals existing around them.
2. Brushtail Possum (Trichosurus vulpecula)
Trichosurus vulpecula is the scientific name of Brushtail possum which is a nocturnal marsupial. It is the size of a cat and mostly lives in trees. It is native to Australia but is an invasive species in New Zealand. Dingoes and bush fires maintain a population check on the possums. The possums feed on eucalyptus leaves resulting in imbalance of vegetation. They also feed on birds which has led to the depletion of bird species such as the kokako bird and kereru pigeons.
1. Red Fox (Vulpes vulpes)
Vulpes vulpes is the scientific name for the red fox. The red fox is the largest real fox in the world. Within its natural habitat, the red fox is essential for checking the populations of rodents and other small mammals. The red fox is native to the Northern Hemisphere, however, whenever it invades other areas, it becomes destructive. In Australia, the red foxes have contributed to the significant decline of native animals such as the newborn lambs. They also carry diseases like rabies. Red foxes can be controlled through poisoning, fencing, and hunting.