Home2019-2020Issue 4Disappearing nutria: Where did they go?

Disappearing nutria: Where did they go?

Sanja Zelen

Staff Writer

 Willamette University has undergone some significant changes this semester: no Montag store, no stir fry in Kaneko, renovation of the University Center—the list goes on. However, one of the biggest changes has gone unnoticed by some returning Bearcats. 

The green lawns have been looking emptier than usual this semester. There have been fewer sightings of glowing eyes at night in the light of iPhone flashlights. One of Willamette’s most asked questions, “Is that a beaver or a bearcat?” has barely been uttered.

That’s right: the nutria are gone. The brown semi-aquatic rodents, up to 14 pounds in size, have mysteriously disappeared from Willamette’s campus. Over the years, their presence on campus has manifested itself into jokes, memes and Instagram accounts. 

Mickey Cochrane, groundskeeper at Willamette, offered answers to the pressing question of the nutria’s whereabouts. Cochrane recalls last seeing a nutria on campus well before graduation in May. 

“It’s one of those unanswered phenomenons that has occurred. I think the reason they may have left is because we stopped feeding them. They may have just went on to some place that has a better food source. Maybe they went back to South America, where they came from.”

Nutria are highly invasive to Oregon. According to an Oregon Department of Fish and Wildlife report by Done VandeBergh, nutria were first introduced to California in 1899 to be used for their pelts and to compensate for the loss of beavers to overhunting. Since the pelt business was ultimately unsuccessful, the fur traders released the captured nutria into the wild, where they started to spread across the southern and northwestern United States.

Cochrane recalls when and how they first appeared at Willamette:

“They weren’t around for years, but it was just several years ago that we had a couple show up, and then we fed them all the time and they got full grown. All of Salem’s waterways are connected; there are all these streams and swamps around Salem. The nutria just come down the waterways. They’re a water animal. They just set up a home here. They’re pretty safe here on campus.”

Free from predators and sustained by a reliable water and food source, the nutria had made Willamette’s Mill Stream their home over the years. Cochrane notes several changes around campus that could explain their sudden migration.

“Salem does drop the water in this creek, especially over the summer to work on it, and there may have been a stretch when it was down pretty low for two or three days. Nutria burrow along the water’s edge for safety, so maybe they thought there was no water left and they just moved on.”

David Craig, professor of biology at Willamette, remembers a disease outbreak in 2005 that affected a majority of Salem’s nutria. He speculates that a similar epidemic could have affected the nutria population over the summer.

“I think an Epizootic Pneumonia is the best explanation for the missing nutria based on the complete absence of animals.” Craig defines this type of pneumonia as being widespread and caused by an infection. 

“I recall seeing a couple of weezing, shallow breathing juveniles [in 2005] and then the next week the nutria vanished. Diseases caused by microbial infections can result in significant mortality in nutria populations, especially in times of high population densities.”

There is a possibility that the nutria escaped this fate this year and are still around campus, since they are nocturnal animals. However, Cochrane’s observation of the campus’s ecology suggests otherwise.

“I think they’re gone. I don’t see any evidence of them in the Botanical Garden. They would come and eat the grass down and I don’t see that, so I do believe they’ve gone on their way.”

Considering nutria are invasive, their migration could serve as a benefit for Willamette. According to VandeBergh, nutria are a disturbance to waterways, since they “dig up roots, tubers, and bulbs, which disrupts soil stability and changes the hydrology of an area.” In addition, they spread disease and parasites to native animal species, such as muskrats. 

There have been countless attempts to control the negative impacts caused by nutria in Oregon, including setting up traps in waterways and calling a wildlife agency, which can enforce stricter measures. 

“The other potential source for a big population crash could be the use of poison baits,” Craig suggests of campus’ nutria, “but poison rarely kills all individuals and would require application by a USDA APHIS agent.”

The exact location of Salem’s nutria remains a mystery. They could have sought out areas in Salem with a more consistent water and food source, could have been wiped out by disease or may have simply migrated for the time being. 

Students should be on the lookout for nutria and contact Grounds if they spot one of them again. Should the nutria make an appearance, students should be sure to observe them from a distance. In the words of Cochrane, “Who knows what lurks in the mind of a nutria?”

szelen@willamette.edu

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