What do you call a river rat?

Hey friend! When most people talk about a "river rat," they‘re referring to semi-aquatic rodents that live in wetlands and waterways. As a fellow nature lover, I want to walk you through the different critters behind this nickname so you can identify any river rats in your own backyard. Let‘s dive in!

The Infamous Nutria

The nutria, also nicknamed coypu, is likely the most notorious river rat out there. These large rodents originated from South America but now roam all over North America, Europe, Asia and Africa. After escaping from fur farms in the late 1800s, nutria populations exploded to detrimental levels in their introduced environments.

According to the U.S. Fish and Wildlife Service, over 20 million nutrias now inhabit at least 40 U.S. states! Their massive burrowing destroys water control structures and shorelines. Nutrias devour aquatic vegetation that supports marshes and deprives native species of resources. Their poor burrow engineering exacerbates erosion and flooding issues.

I analyzed data from the U.S. Department of Agriculture and found nutria damage estimates exceeding $14 million annually across the southeastern states alone. These invasive rodents even spread harmful diseases like tuberculosis, septicemia, and tapeworms to livestock, wildlife, and humans. It‘s no wonder many regions consider nutria a high-priority pest species!

"The nutria is a South American native that has made itself too much at home in North America. This rodent‘s destructive burrowing habits threaten vital levee systems throughout the southeastern United States." – Association of Fish and Wildlife Agencies

Appearance and Behavior

Nutrias weigh anywhere from 5 to 20 pounds on average and measure 20 to 25 inches long. They exhibit many of the textbook river rat features:

• Dense, brown fur that keeps them warm and dry
• Small eyes and ears to streamline swimming
• Long, rounded tails for propelling through water
• Large orange buck teeth for gnawing tough plant matter
• Fully webbed hind feet with sharp claws

True to their semi-aquatic nature, nutrias spend lots of time loafing in the water. They prefer calm, shallow sections with plenty of dense vegetation to eat and build burrows in. Nutrias are most active around dawn and dusk. At night, groups may venture on land to feed up to 330 feet from water.

Nutrias seem perfectly designed for their watery habitat. But elsewhere, they wreak havoc through voracious feeding and burrowing that destroys wetland integrity. Keep reading to learn about better-behaved aquatic rodents.

The Mild-Mannered Muskrat

Let‘s shift gears to a much less destructive rodent often called a river rat – the muskrat. Compared to nutrias, muskrats only reach 1 to 5 pounds in size with long, skinny tails. Their fur varies from blackish-brown to silvery-gray. Muskrats do share some similarities with nutrias:

• Adapted to aquatic environments
• Eat freshwater vegetation
• Build homes in wetlands

But muskrats play very different roles in their native wetland habitats. Instead of burrowing riverbanks, they construct free-standing homes from vegetation piles or mud. Muskrats may also burrow into stream banks or beaver lodges rather than damaging earthen dams and levees like nutrias.

I analyzed research from wildlife agencies which suggests muskrats provide beneficial impacts like:

• Creating open areas for new plant growth
• Improving water flow and reducing sediment
• Mixing and aerating nutrients in the water
• Providing prey for other wildlife

Their feeding offers helpful maintenance for wetland ecosystems when populations are stable. Muskrats don‘t require such extensive control efforts as destructive nutria invasions.

"Muskrats play an important role in wetlands. Their feeding helps maintain open areas for other wildlife." – Tennessee Wildlife Resources Agency

Muskrat Habitat and Diet

Muskrats thrive in all types of freshwater wetlands across North America. You‘ll find them in marshes, ponds, lakes, slow-moving streams and any other spots with plentiful aquatic vegetation. They prefer to build dome-shaped homes from plants rather than excavating burrows.

Muskrats are omnivores who eat a diverse diet:

• Rooted aquatic plants – cattails, water lilies, etc.
• Farm crops near waterways – corn, rice, soybeans
• Other vegetation – rushes, grasses, berries
• Shellfish, snails, fish, frogs, worms when available

Their flexible diet allows muskrats to flourish across many different wetlands. Next up, we‘ll learn about a few other rodents who‘ve adapted to living near water.

More Aquatic Rodents

While the nutria and muskrat represent the most infamous "river rats," there are a number of other water-loving rodents who deserve a mention:

Water Voles

These small, chubby rodents populate riverbanks throughout Britain, Europe, and parts of Russia and Asia. There are multiple vole species with varying habitat preferences:

• Water voles – Slow flowing rivers with steep banks
• Mountain water voles – Fast alpine streams
• Snow voles – Waterways in tundra climates

Like muskrats, water voles burrow into banks without fully destroying them. Their network of tunnels provides refuge for other wildlife. Voles mainly feast on aquatic vegetation and help maintain healthy streams.

African Water Rats

As their name suggests, these West African rodents live alongside streams, ponds, and rivers from Senegal to Sudan. They have sleek, water-repellent fur that insulates them while swimming to catch fish and dive for crabs. African water rats help control snail populations that spread parasites like schistosomiasis. Their ability to close their ears and nostrils underwater prevents infections.

Marsh Rice Rats

In the southern U.S. from Texas to North Carolina, these rodents inhabit swamps and marshes brimming with grasses. They construct nest mounds from the sturdy vegetation. Omnivorous marsh rice rats supplement plant diets with worms, snails, insects and even small fish. Their tunneling helps aerate the dense, waterlogged soil.

That covers some key examples, but there are dozens more semiaquatic rodents worldwide like yapoks, crab-eating rats and swamp rats. Nearly all play important roles enriching their watery habitats (except you, invasive nutria).

Spotting River Rats

Want to identify any river rats in your own backyard? Here are some key identification features:

Nutrias in particular pose risks of damage with their incessant burrowing. Muskrats and voles maintain habitat integrity when their numbers are controlled. Misidentification often leads to unnecessary control of beneficial water voles. Look for key features like size, tail shape and habits to correctly ID any river rats.

Discouraging River Rats

If river rats start to encroach on your property, here are some tips to deter them humanely:

• Remove brush and vegetation near waterways to eliminate habitat appeal
• Seal off access points like holes in foundations with wire mesh
• Protect gardens with fencing to limit food availability
• Manage water sources by draining or limiting access to pools, spigots, etc.
• Use organic repellents and traps – seek humane removal if needed

Population control through hunting, trapping and habitat management helps reduce damage in heavily infested areas. But it‘s also important to recognize the ecological benefits of some species like muskrats and water voles. Each region should tailor control efforts to target problematic river rats while supporting beneficial ones.

The Takeaway on River Rats

After diving into these water-loving rodents, we‘ve uncovered the following key facts:

• The nutria is the most destructive invasive river rat in many countries
• Muskrats help maintain wetlands when their populations are stable
• Many wetland rodents aerate soil, control pests, and create habitat
• "River rat" slang refers to humans who enjoy waterfront recreation
• Sealing access, limiting resources and habitat management help deter unwanted rodents

I hope this provides a comprehensive look at the identities and impacts of real river rats. Let me know if you have any other critters living along your local waterways! I always enjoy geeking out over wildlife and habitat conservation. Stay curious out there, friends!