Exotic Animals - the pros and cons
The word exotic means “imported from another country” or “not native to the place where found.” In terms of nature, exotics are animals or plants that are not historically found in the area they’re living in. Some of them might have been introduced intentionally, others accidentally.
In some cases exotics have been very successful and provide benefits to the environment and people who enjoy it. Other exotics can be real troublemakers.
All organisms on earth fill an ecological niche. This means that they survive in a relationship with all the other plants and animals in the environment.
When a new species is introduced, it can fill a vacant niche and become a valuable asset to the ecosystem. If it needs to compete with other organisms already in that niche, one of them will likely be eliminated from the system.
The introduction of new species into the wild is controlled by wildlife agencies and the U.S. Department of Agriculture. Officials want to be very careful about what species are moved around and how they will affect those already living in each niche.
An exotic success story
Ring-necked pheasants were first introduced in America in the mid 1800s. Originally from China, these game birds quickly became established in a niche that was unfilled.
Farms at that time had lots of fence lines and ditch banks, perfect habitat for pheasants, but not so great for the native birds, such as grouse, which preferred more undisturbed habitat.
Pheasants are now found throughout the United States and are very popular game birds. They have been around so long it seems like they ought to be considered natives.
An exotic nightmare
Zebra mussels originally came from the lakes of southeast Russia. The first ones to come to America probably hitched a ride in a ballast tank of a ship that sailed into the Great Lakes. The first zebra mussels were discovered in America in 1988.
Since that time they have spread across the United States. They are quite small, but their colonies can grow to cover the bottoms of boats and docks. Sometimes their colonies get so big they plug up pipes and damage other underwater equipment.
Reasons for intentional introductions
FINANCIAL - The most common reason to introduce a new species is to make money. The eurasian carp was brought to America as a source of food. Foxes were introduced to Alaskan islands to supplement the fur trade. The Monterey Pine was transplanted to Australia and New Zealand for its timber production. These are just a few examples of economically motivated introductions.
RECREATIONAL - Some species are introduced for recreational use or some other way of increasing human enjoyment. Brown trout were brought to America from England as a sport fish.
AESTHETICS - Some plants have been introduced because they look nice. The Norway maple is one such plant. Sometimes these plant introductions backfire and the plants become pests. The water hyacinth is one example. They are beautiful plants, but in some places have taken over entire waterways.
NOSTALGIA - Another reason people introduce exotic species is nostalgia. They might have come from a different place or visited a foreign land and seen a species they liked. In order to re-live their pleasant memories, they bring the plant or animal that reminds them of their experiences.
That’s why starlings were introduced to New York City in 1890. Since then, these birds have spread across the land and are often nuisances in both city and agricultural areas.
PROBLEM RESOLUTION - One more reason for species introduction is an attempt to solve an environmental problem. The kudzu plant was brought to America to help control erosion.
Unintentional introductions happen when species are transported by humans without planning to. For example, over 200 different species have been introduced to the San Francisco Bay in ship ballast tank water. Three species of rats have spread to most of the world as hitchhikers on ships.
There is also the accidental release of the Africanized honey bees, sometimes called "killer bees" to Brazil in 1957. They have since spread across south and central America and into the United States.
Sometimes animals kept as pets escape into the wild and reproduce. Domestic animals that have gone wild are called feral. You can find feral cats in every part of the world.
Many non-native species have become such a common part of our lives that we don’t even think about them as being exotics.
For example, soybeans, kiwi fruit, wheat and all livestock except llamas and turkeys are non-native species to North America.
Non-native plants and animals make up 98% of the food produced in America.
Activity: Not in my niche
The animals on the left are native to the United States, those on the right are not. Draw a red line between animals that would be in direct competition with each other for food and habitat. Draw a blue line from those on the right to the ones on the left that they might eat. Draw a circle around the exotic animals that have already been introduced to America.
A note on the niche challenge.
Not even scientists can foresee all the impacts a new species might have on the environment. In this challenge, there my not be a right answer. Discuss the possibilities.
What is an invasive species?
An invasive species is a non-native species that can cause economic harm, environmental harm, or harm to human health. They are aggressive species that grow and reproduce rapidly, causing major problems to areas they move into.
The longer they live in their new environment, the harder it becomes to control them.
Invasive species can be detrimental to the environment and cost people a lot of money. They can reduce crop production, damage timber stands and spread disease among animals, including humans.
Another way they cause problems is by making our outdoor experiences less pleasant. They can make it harder to enjoy hunting, fishing, camping, hiking, boating and other recreational activities.
They can also be a threat to native species. Studies show that almost half (42%) of threatened or endangered species are at risk because of invasive species. Every year people in the United States spend billions of dollars trying to stop the spread of invasive species.
The Burmese python can grow as long as 20 feet and weigh as much as 200 pounds. Join hands with four or more other people and make a python parade. Without letting go of hands, walk around the room or yard, weaving around objects as you go.
Pythons might look scary, but it would be pretty hard for one to catch you. They can only move about one mile an hour. That’s about 1.5 feet per second.
Measure ten feet on the floor and see if you can walk that distance in exactly ten seconds. That’s how fast a python moves. Can you move faster than that?
How many species in America are considered invasive?
82 (mostly game and tropical fish)
78 (mostly feral pets)
32 (mostly rodents or feral pets)
92 (about half feral pets)
31 (mostly ticks and mites)
Venezuelan yellow frog
The American bullfrog can get up to eight inches long, even longer if you count its extended legs.
They are very aggressive and will eat anything that fits in their mouth. They eat fish, mice and baby ducks.
Some people like to eat frog legs and have introduced these big amphibians all over the globe.
One of the species they have become a threat to is the Venezuelan yellow frog.
Now people are trying to control the bullfrog before it’s too late for the yellow frog.
These silver carp (below) are an invasive species. They jump into the air when they are disturbed by the sound of a boat motor.
Because of their large size, voracious appetite, and high reproductive rate they are a very real threat to the Great Lakes ecosystem. Scientists are concerned that the Asian carp would eat such large quantities of phytoplankton that they would upset the ecological balance of the lakes. They would also compete with native fish for habitat.
Jumping silver carp
Illegal introductions hurt the environment and reduce recreational opportunities.
Many wildlife agencies are facing an epidemic of illegal stocking of fish, Sometimes called "bucket biology." In most states it is illegal to transport live fish without a permit or to dump live fish into any water.
"It's a national problem that's rapidly spreading across Montana," said Chris Hunter, chief of fisheries for Montana Fish, Wildlife & Parks in Helena. "We believe that more than 20 percent of Montana's illegal fish introductions occurred in the past 10 years."
FWP recently confirmed the state's 500th unauthorized fish introduction. At least 50 different species of fish have been illegally dumped into state waters.
"It's an epidemic that's threatening Montana's native fish populations and the state's planned for and managed fisheries from Lake Mary Ronan near Polson to Broadwater Pond near Billings," Hunter said.
Illegally introduced fish and other aquatic species can harm native, wild and stocked fish populations, spread disease, and create water-quality problems. The consequences of an illegal fish introduction diminishes fishing opportunities and increases management costs by exhausting hatchery stocks or by requiring the rehabilitation of a lake or stream to restore a fishery.