Invasive vs. native: Why it is dangerous to release non-native animals

Inspiration for columns arrive at my desk from many different angles. Some, of course, develop in my own mind. Others are suggested by readers, family and friends.

Recently the following e-mail arrived in my inbox from Assistant District Wildlife Biologist Ella Rowan: “Dennis, perhaps you can do an article on the damage caused and millions (if not billions) of dollars in eventual damage by people releasing non-native animals.

“Releases of non-native mussels or plants on boats is presumably unintentional and due to ignorance or being lazy, but many animal releases are intentional. We occasionally find released “pets” such as pythons or get reports about released animals.

“Reading about the problems Florida has with pythons should be enough to convince anyone who cares about native wildlife that they will destroy native populations. While our winters are sometimes cold enough to kill many non-native species from warmer climates, they aren’t long and cold enough to kill many.

“Outdoor and feral cats are the worst offenders when it comes to wildlife mortality by a non-native. They kill billions of songbirds, billions of mammals, likely as many others species such as lizards, butterflies and just about anything that moves.

“Pet turtles and bullfrogs released kill native species through the diseases they have, and predation (by bullfrogs). Pythons, nutria, pike, other fish…the damage is enormous and sometimes impossible to reverse (such as introduced bullfrogs, non-native deer farms with exotic lice that escape and infect native deer, CWD which is sometimes moved around by elk farms, etc.).

“Just a few birds released nearly 100 years ago in the eastern US has turned into the overwhelming populations of house sparrows, European starlings, and Eurasian collared doves that out-compete native species for food and nest sites.”

Ella’s message arrived months ago. This has allowed time to consider a plan to present all of this information to my readers. It is time.

Therefore, this week is dedicated to addressing the questions of invasive vs. native species in Eastern Washington. We will not be able to discuss all invasive species, but we can cover a bunch of them.

Today we discuss the nutria. This animal looks like a large rat, which can weigh between 15 and 20 pounds. It was first imported from South America between the late 1800s through 1930. The incentive was to bolster the fur industry.

Only one live nutria has crossed my path in the wild. My boat was anchored near Split Rock on South Twin Lake on the Colville Indian Reservation.

There was no sound, but movement caught my eye. A nutria was swimming past at about five feet distance. Then it was gone, out of site.

Tomorrow: Another invasive species.