Swamp ro­dents set off Calif. alarms

Armed with $10M, agency takes aim at in­va­sive nu­tria

The Morning Call - - NATION & WORLD - By Sa­man­tha Mal­don­ado and Terry Chea

LOS BANOS, Calif. — One of the most re­cent threats to Cal­i­for­nia’s en­vi­ron­ment has webbed feet, white whiskers, shaggy fur and or­ange buck teeth that could be mis­taken for car­rots.

“Boy, they’re an ugly-look­ing thing,” said David Pas­sadori, an al­mond and wal­nut grower in cen­tral Cal­i­for­nia. “And the way they mul­ti­ply — jeez.”

The swamp ro­dents, called nu­tria, are set­ting off alarms in Cal­i­for­nia. They weigh about 20 pounds each and eat the equiv­a­lent of about a fourth of their weight each day by bur­row­ing into river­banks and chomp­ing into plants that emerge from the wa­ter.

The an­i­mals can de­stroy the wet­land habi­tats of rare and en­dan­gered species, de­grad­ing soil, ru­in­ing crops and car­ry­ing pathogens that may threaten live­stock.

Most of all, they pose a public safety risk: Left unchecked, nu­tria could jeop­ar­dize Cal­i­for­nia’s wa­ter sup­ply, es­pe­cially if they get into the Sacra­mento-San Joaquin River Delta.

The delta is the “heart­beat of Cal­i­for­nia’s wa­ter in­fra­struc­ture,” ac­cord­ing to Peter Tira, spokesman for the state’s Depart­ment of Fish and Wildlife. It con­tains a net­work of more than 1,000 miles of canals and lev­ees that pro­tect the area from flood­ing, pro­vide drink­ing wa­ter to mil­lions of Cal­i­for­ni­ans and ir­ri­gate the lush agri­cul­tural re­gion.

Now, armed with $10 mil­lion in state funds, the wildlife agency is de­ploy­ing new tac­tics to erad­i­cate the nu­tria and try to pre­vent the wide­spread de­struc­tion they are known to cause.

“Over the past two years, our best ef­forts were try­ing to not even con­trol the pop­u­la­tion but keep it from ex­plod­ing while we pur­sued the re­sources needed to ac­tu­ally pur­sue erad­i­ca­tion,” said Va­lerie Cook, en­vi­ron­men­tal pro­gram man­ager for Fish and Wildlife’s newly es­tab­lished Nu­tria Erad­i­ca­tion Pro­gram.

“We haven’t had nu­tria in Cal­i­for­nia for 50 years, so no­body re­ally knows much about them,” Tira said. “We’ve had to learn on the job as we go.”

An in­va­sive species orig­i­nally from South Amer­ica and brought to the United States at the height of the fur trade in the late 19th cen­tury, nu­tria were be­lieved to have been erad­i­cated in the state in the 1970s un­til one turned up in a beaver trap in 2017. Since then, more than 700 nu­tria have been trapped and killed, in­clud­ing four on Pas­sadori’s prop­erty.

Farm­ers, landown­ers and bi­ol­o­gists in the Cen­tral Val­ley, an agri­cul­tural re­gion 130 miles north of Sacra­mento, have been on high alert.

On a re­cent morn­ing in Merced County, where the most nu­tria have been found, state bi­ol­o­gists Greg Ger­sten­berg and Sean McCain pad­dled in kayaks in a wet­land pond thick with cat­tails. Wear­ing waders, they trudged through chest-deep wa­ter to check surveil­lance cam­eras and cage traps where they leave sweet potato pieces to en­tice the in­va­sive ro­dents.

Last year, wildlife of­fi­cials re­moved al­most 90 nu­tria from this pond. Ger­sten­berg and McCain have re­turned be­cause they be­lieve at least a few nu­tria are back. But on this morn­ing they found only muskrats, smaller swamp-dwelling ro­dents, and re­leased them back into the pond.

“Our goal is to get out here and find them and erad­i­cate them be­fore they be­come fully es­tab­lished through­out our Cen­tral Val­ley,” said Ger­sten­berg, a se­nior Fish and Wildlife bi­ol­o­gist.

The Cen­tral Val­ley is the United States’ most pro­duc­tive agri­cul­tural re­gion, re­spon­si­ble for more than half the na­tion’s fruits, veg­eta­bles and nuts, in­clud­ing al­most all its apri­cots, ta­ble grapes, car­rots, as­para­gus and tree nuts. Fed­eral Depart­ment of Agri­cul­ture fig­ures put the mar­ket value of Cen­tral Val­ley agri­cul­tural pro­duc­tion in 2017 at al­most $29 bil­lion.

Dam­age to the re­gion’s soil or wa­ter in­fra­struc­ture would be dev­as­tat­ing to the econ­omy and diet.

“It would mean no more sushi be­cause the al­ter­na­tive would be to buy rice from Ja­pan or Korea, where the price is five times higher,” said Daniel Sum­ner, direc­tor of the Agri­cul­tural Is­sues Cen­ter at the Univer­sity of Cal­i­for­nia-Davis. “Kiss off car­rots, or live with­out ta­ble grapes in the sum­mer­time.”

Trail cam­eras and landown­ers have helped lo­cate the elu­sive, noc­tur­nal crea­tures over an area of al­most 13,300 square miles that wildlife of­fi­cials are eval­u­at­ing for nu­tria habi­tats. Live traps baited with sweet potato do­nated by farm­ers help cap­ture them. Once iden­ti­fied as nu­tria, the an­i­mals are shot. Tira said about three-quar­ters of fe­male nu­tria have been found preg­nant — they can have up to three lit­ters a year, al­low­ing them to re­pop­u­late quickly.

The new at­ten­tion and fund­ing will al­low Fish and Wildlife to hire 46 ded­i­cated staff. By De­cem­ber, the agency will launch what’s known as a Ju­das Nu­tria pro­gram that would out­fit sur­gi­cally ster­il­ized nu­tria with ra­dio col­lars and send them out in the wild. Be­cause the an­i­mals are so so­cial, they will lead the team to other nu­tria.

Be­fore year’s end, Fish and Wildlife will start ge­net­i­cally test­ing the nu­tria to de­ter­mine where they came from. Tira said mi­gra­tion from Ore­gon or Wash­ing­ton is doubt­ful, but the team isn’t sure whether the nu­tria were rein­tro­duced to Cal­i­for­nia or part of a rem­nant pop­u­la­tion.

Tak­ing a cue from Mary­land’s eastern shore and parts of Delaware and Vir­ginia, of­fi­cials also will test dogs trained to sniff out the ro­dents’ scent and scat.

“We can’t be suc­cess­ful if we can’t find ev­ery sin­gle an­i­mal,” Cook said.

Be­sides threat­en­ing agri­cul­ture and in­fra­struc­ture, nu­tria can harm wet­lands, which play a crit­i­cal role in keep­ing car­bon diox­ide out of the at­mos­phere and help­ing mit­i­gate global warm­ing.

The Cen­tral Val­ley also hosts the largest con­cen­tra­tion of mi­gra­tory water­fowl on Earth, said Ric Ortega, the Grass­land Wa­ter Dis­trict’s gen­eral man­ager.

“We only have so much sur­face wa­ter stor­age in Cal­i­for­nia,” he said. “It’s not a wet­land if it’s not wet. The nu­tria com­pli­cate that.”


The swamp ro­dents, known as nu­tria, are an in­va­sive species orig­i­nally from South Amer­ica that were brought to the U.S. in the late 19th cen­tury.

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