February 26, 2025 • 14 mins
In honor of National Invasive Species Awareness Week, Sarah Marsh Janish discusses the recent focus on nutria in California. Although this semi-aquatic mammal is not new to California, the surge in population and range across the state is of some concern, especially to those of us who work in the habitats they prefer to inhabit.
Report Nutria: "Suspected observations or potential signs of nutria in California should be photographed and immediately reported to CDFW ONLINE, by email to Invasives@wildlife.ca.gov, or by calling (866) 440-9530."
Nutria Links
UCCE Annual Meeting - Emerging Pest Presentation
Upcoming Events!
Propanil Stewardship Meetings
March 17 in Woodland at the Yolo County Farm Bureau office
March 18 in Richvale at the Community Church.
Other Resources
UC Rice Blog
UC ANR is an equal opportunity provider and employer
Mark as Played
Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
SPEAKER_03 (00:00):
Hello and welcome to Thoughts on Rice, a podcast
hosted by the University ofCalifornia Cooperative Extension
Rice Advisors.
I'm one of your hosts, SarahMarchionish, and I'm a rice farm
(00:21):
advisor for Colusa and Yolocounties.
SPEAKER_00 (00:24):
I'm Whitney from DeForest.
I'm the Cooperative ExtensionRice Advisor for Sutter, Yuba,
Placer, and Sacramento counties.
SPEAKER_01 (00:32):
My name is Luis Espino.
I'm the Rice Farming SystemsAdvisor for Butte and Glynn
counties.
SPEAKER_02 (00:39):
I'm Michelle
SPEAKER_01 (00:40):
Leinfelder-Miles.
SPEAKER_02 (00:41):
I'm a farm advisor in the Delta region.
I work on all sorts of fieldcrops, grains and forages, but
one of those is rice.
And the counties that I coverare San Joaquin, Sacramento,
Yolo-Solano, and Contra Costacounties.
SPEAKER_03 (00:56):
Together, the UCC rice farm advisors seek to
provide relevant, topical,research-backed information
relating to California riceproduction.
Forgive me if I sound a bit offtoday.
We just got back from the RiceTechnical Working Group
(01:17):
conference in New Orleans lastweek, and I have been fighting
off the cold that everybodyseemed to have.
Disregarding that, it was afantastic conference, with a lot
of great talks from all over theUS and the globe, and I can't
wait to go to the next one inTexas in 2027.
Today, in honor of InvasiveSpecies Week, I'll be discussing
(01:37):
the recent focus on Nutria inCalifornia.
Although this semi-aquaticmammal is not new to California,
the search Urge and populationand range across the state is of
some concern, especially tothose of us who work in the
habitats they prefer to inhabit.
This talk is paraphrased fromone that I gave during the
annual UCCE grower meetingsearlier this month, so if it
(02:00):
sounds a bit familiar, that'swhy.
Music Nutria, or koipu if that'sa name you're more familiar
(02:22):
with, are large semi-aquaticrodents that are native to South
America.
The species is invasive in theU.S.
and currently established in 17states, including California.
Nutria inhabit both freshwaterand brackish coastal water areas
and can be found near permanentwater sources, including rivers,
(02:43):
streams, lakes, ponds, wetlands,and continual rice production.
However, they can still thrivein urban conditions.
In cities, they can be found intheir buildings, in overgrown
lots, on golf courses, and instorm drains.
Nutria thrive in warmerconditions, such as the
southeastern region of the U.S.,and their reproductive success
(03:06):
is reduced by severe winterconditions.
However, that's not to saythey're not found in the north.
They are there.
They just have a little bit lesssuccess in terms of
reproduction.
They can grow in size up to 20pounds and have partially webbed
feet.
Often mistaken for small beaveror very large muskrats, Nutria
(03:27):
can be differentiated by largefront teeth that are yellow to
orange in color, a heavy,rat-like tail, and prominent
white whiskers that protrudefrom either side of their nose.
Incidentally, Nutria haveactually been present in
California for over a century.
Introduced in 1899 to stoke thefur trade, the first members of
(03:49):
the species were spectacularlyunsuccessful, and the species
was declared eradicated fromCalifornia in the 1970s.
This remained true until thespring of 2017, when the
California Department of Fishand Wildlife, or CDFW, trapped
and necropsied a pregnant femalenutria in Merced County.
(04:10):
This action triggered monitoringand eradication efforts across
the state, which have indicatedthat nutria is spreading further
north every year.
Nutria are known for theirherbivory and burrowing
behavior, which we'll go furtherinto detail about, but they also
serve as hosts for tuberculosisand septicemia, which are
(04:30):
threats to humans, livestock,and pets.
Additionally, nutria carrytapeworms, a nematode that
causes a rash known as nutriaitch, and blood and liver
flukes, which can contaminateswimming areas and drinking
water supplies.
Nutria can consume up to 25% oftheir body in above and below
(04:51):
ground plant tissue, but theycan waste and destroy up to 10
times as much.
They clip the plant stems at thewaterline and can denude entire
landscapes with relatively smallpopulations, causing extensive
damage to the native plantcommunity and soil structure, as
well as significant losses tonearby agricultural crops.
(05:14):
Nutria do not make dens, butrather burrow into levees,
riverbanks, or other watercontrol structures, frequently
causing water retention or floodcontrol levees to breach,
weakening structuralfoundations, and eroding banks.
Thanks.
Their burrows have entrances atthe waterline for easy access
from the water.
Additionally, nutria can beproblematic in the ways that
(05:37):
they increase their populations,because this species is
excellent at population growth.
Nutria are such prolificbreeders that one female can
lead to 200 offspring in just ayear.
In a population modelingexperiment from Oregon State
University, a hypotheticalnutria population was mapped,
(05:58):
assuming two litters per yearand a 20% predation or loss
rate.
One breeding pair, after fiveyears, resulted in 2,048 nutria.
Part of the reason of thisexponential population growth is
because nutria reach sexualmaturity at about four to six
months.
Females have anywhere from fiveto seven babies in a litter, and
(06:22):
they can have several littersevery year.
Additionally, nutria have a highrate of migration and can The
current geographic distributionof nutria in California concerns
those of us involved in riceproduction.
Current maps from the CDFW placenutria hotspots in the Delta,
(06:45):
near rice production areas.
However, maps also show thatnutria is being spotted as far
north as Fairfield, which startsencroaching on the Sacramento
Valley rice production areas.
As the preferred habitat ofthese rodents is identical to
that of a rice field, thepotential for damages is high.
Additionally, identifying therice damage caused specifically
(07:08):
by nutria can be challenging, asit is easy to confuse it with
the damage caused by muskrats,as both rodents clip the stems
of the rice plants at thewaterline.
At high densities, nutria cansubstantially impact plant
communities.
In the U.S., rice is one of theprime However, nutria also favor
(07:31):
crops and plants that canneighbor rice fields, including
corn, grain sorghum, alfalfa,wheat, barley, oats, melons, and
a variety of vegetables fromhome gardens and farms.
When it comes to current methodsto try and control the spread of
nutria in California, CDFW iscollaborating with other
(07:53):
agencies and local partners todevelop the most effective
strategy for eradicating nutriafrom California.
CDFW believes that the currentstate of nutria population in
California indicates thateradication is possible if rapid
response is taken.
This is really good news,especially compared to other
(08:13):
states where eradication is nolonger a feasible goal, but
instead population control isthe attempt.
As an example, the nutriapopulation in Louisiana, where
the population control costs upto$2 million per year for bounty
harvest alone, is an indicationwhere eradication is not an
option.
(08:35):
In California, nutria areclassified as a non-game animal.
Fish and Game Code 4152specifies that property owners
or their agents who possesswritten permission from the
owner or tenant may take nutriaat any time by any legal means
to address damage to crops orproperty.
(08:56):
Restrictions apply to the use oftraps and the types of traps,
but this does indicate aterminal take, because nutria
are a restricted species inCalifornia under the California
Code of Regulations, Title 14,Sections and cannot be imported,
transported, or possessed livein the state of California.
(09:17):
In other states, bounty programsare underway to encourage the
taking of nutria.
However, in California, it isillegal to offer a bounty for
nutria.
California Fish and Game CodeSection 2019 clearly states, it
is unlawful for any person,including state, federal,
county, and city officials ortheir agents, to authorize,
(09:39):
offer, or or pay a bounty forany bird or mammal.
State legislation changes wouldhave to take place to alter the
code to provide an exemption fornutria.
Any nutria taken on private orpublic land should be reported
to CDFW as soon as possible forpurposes of delineating the
extent of the infestation.
(10:01):
At minimum, CDFW needs photos toconfirm identification.
Preferably, CDFW needs thecarcass to determine sex, age,
and reproductive status.
Suspected observations orpotential signs of nutrient
California should bephotographed and immediately
(10:21):
reported to CDFW online, byemail to
invasivesatwildlife.ca.gov, orby calling 866-440-9530, and
we'll have that informationlinked in the show notes.
Observations on state or federallands should be immediately
(10:41):
reported to local agency staff.
If this species is captured, donot release it.
Immediately contact your localCDFW office or county ag
commissioner.
Finally, to wrap up, I'mreaching out to you, our
listeners.
If you live in California andyou think you've seen a nutria,
(11:01):
let us know.
We're hoping to raise awarenessof this invasive pest in the
state.
Feel free to reach out throughany of the contact methods I'm
going to mention shortly.
(11:26):
We have a few upcoming events.
The UCCE Rice team will beholding a propanil stewardship
meeting.
And this will take place in twolocations on two different
dates, but it'll be the samemeeting.
And the first will be March 17thin Woodland at the Yolo County
(11:47):
Farm Bureau office.
And the second date will beMarch 18th in Richvale at the
Community Church.
We'll have the agenda and allother information up on our
resources, but that is still tobe announced.
So for more information aboutthese and other upcoming events,
feel free to check out ourresources, which include the UC
(12:07):
Rice blog and the UC AgronomyRice website.
In terms of other resources youmay want to take advantage of,
you can also look at our Thanksfor listening to Thoughts on
(12:38):
Rice, a University of CaliforniaCooperative Extension podcast
from the University ofCalifornia Agriculture and
Natural Resources.
You can find out more about thispodcast on our website,
thoughtsonrice.buzzsprout.com.
We'd love to hear from you,whether it's from using our text
link in the show notes, a surveysubmission in our feedback form,
(13:00):
also in the show notes, or in acomment or rating on your
podcast streaming service ofchoice.
We're also experimenting withpolls on Spotify, so if you're
listening on Spotify, you mayhave an option to answer some of
those questions, and we might beable to talk about that on air.
You can also email us with anycomments, questions, or concerns
(13:21):
at thoughtsonrice atucdavis.edu.
Spring has sprung for those ofus here in the Sac Valley, and
rice season is right around thecorner.
Remember, like the growers liketo say, Have a rice life.
Mention of an agrochemical doesnot constitute a recommendation,
(13:44):
merely the sharing of researchfindings.
Always follow the label.
The label is the law.
Find out more at ipm.ucanr.edu.
The views, thoughts, andopinions expressed are the
speaker's own and do notrepresent the views, thoughts,
and opinions of the Universityof California.
(14:04):
The material and informationpresented herein Thank you.
Hello and welcome to Thoughts on Rice, a podcast
hosted by the University ofCalifornia Cooperative Extension
Rice Advisors.
I'm one of your hosts, SarahMarchionish, and I'm a rice farm
(00:21):
advisor for Colusa and Yolocounties.
SPEAKER_00 (00:24):
I'm Whitney from DeForest.
I'm the Cooperative ExtensionRice Advisor for Sutter, Yuba,
Placer, and Sacramento counties.
SPEAKER_01 (00:32):
My name is Luis Espino.
I'm the Rice Farming SystemsAdvisor for Butte and Glynn
counties.
SPEAKER_02 (00:39):
I'm Michelle
SPEAKER_01 (00:40):
Leinfelder-Miles.
SPEAKER_02 (00:41):
I'm a farm advisor in the Delta region.
I work on all sorts of fieldcrops, grains and forages, but
one of those is rice.
And the counties that I coverare San Joaquin, Sacramento,
Yolo-Solano, and Contra Costacounties.
SPEAKER_03 (00:56):
Together, the UCC rice farm advisors seek to
provide relevant, topical,research-backed information
relating to California riceproduction.
Forgive me if I sound a bit offtoday.
We just got back from the RiceTechnical Working Group
(01:17):
conference in New Orleans lastweek, and I have been fighting
off the cold that everybodyseemed to have.
Disregarding that, it was afantastic conference, with a lot
of great talks from all over theUS and the globe, and I can't
wait to go to the next one inTexas in 2027.
Today, in honor of InvasiveSpecies Week, I'll be discussing
(01:37):
the recent focus on Nutria inCalifornia.
Although this semi-aquaticmammal is not new to California,
the search Urge and populationand range across the state is of
some concern, especially tothose of us who work in the
habitats they prefer to inhabit.
This talk is paraphrased fromone that I gave during the
annual UCCE grower meetingsearlier this month, so if it
(02:00):
sounds a bit familiar, that'swhy.
Music Nutria, or koipu if that'sa name you're more familiar
(02:22):
with, are large semi-aquaticrodents that are native to South
America.
The species is invasive in theU.S.
and currently established in 17states, including California.
Nutria inhabit both freshwaterand brackish coastal water areas
and can be found near permanentwater sources, including rivers,
(02:43):
streams, lakes, ponds, wetlands,and continual rice production.
However, they can still thrivein urban conditions.
In cities, they can be found intheir buildings, in overgrown
lots, on golf courses, and instorm drains.
Nutria thrive in warmerconditions, such as the
southeastern region of the U.S.,and their reproductive success
(03:06):
is reduced by severe winterconditions.
However, that's not to saythey're not found in the north.
They are there.
They just have a little bit lesssuccess in terms of
reproduction.
They can grow in size up to 20pounds and have partially webbed
feet.
Often mistaken for small beaveror very large muskrats, Nutria
(03:27):
can be differentiated by largefront teeth that are yellow to
orange in color, a heavy,rat-like tail, and prominent
white whiskers that protrudefrom either side of their nose.
Incidentally, Nutria haveactually been present in
California for over a century.
Introduced in 1899 to stoke thefur trade, the first members of
(03:49):
the species were spectacularlyunsuccessful, and the species
was declared eradicated fromCalifornia in the 1970s.
This remained true until thespring of 2017, when the
California Department of Fishand Wildlife, or CDFW, trapped
and necropsied a pregnant femalenutria in Merced County.
(04:10):
This action triggered monitoringand eradication efforts across
the state, which have indicatedthat nutria is spreading further
north every year.
Nutria are known for theirherbivory and burrowing
behavior, which we'll go furtherinto detail about, but they also
serve as hosts for tuberculosisand septicemia, which are
(04:30):
threats to humans, livestock,and pets.
Additionally, nutria carrytapeworms, a nematode that
causes a rash known as nutriaitch, and blood and liver
flukes, which can contaminateswimming areas and drinking
water supplies.
Nutria can consume up to 25% oftheir body in above and below
(04:51):
ground plant tissue, but theycan waste and destroy up to 10
times as much.
They clip the plant stems at thewaterline and can denude entire
landscapes with relatively smallpopulations, causing extensive
damage to the native plantcommunity and soil structure, as
well as significant losses tonearby agricultural crops.
(05:14):
Nutria do not make dens, butrather burrow into levees,
riverbanks, or other watercontrol structures, frequently
causing water retention or floodcontrol levees to breach,
weakening structuralfoundations, and eroding banks.
Thanks.
Their burrows have entrances atthe waterline for easy access
from the water.
Additionally, nutria can beproblematic in the ways that
(05:37):
they increase their populations,because this species is
excellent at population growth.
Nutria are such prolificbreeders that one female can
lead to 200 offspring in just ayear.
In a population modelingexperiment from Oregon State
University, a hypotheticalnutria population was mapped,
(05:58):
assuming two litters per yearand a 20% predation or loss
rate.
One breeding pair, after fiveyears, resulted in 2,048 nutria.
Part of the reason of thisexponential population growth is
because nutria reach sexualmaturity at about four to six
months.
Females have anywhere from fiveto seven babies in a litter, and
(06:22):
they can have several littersevery year.
Additionally, nutria have a highrate of migration and can The
current geographic distributionof nutria in California concerns
those of us involved in riceproduction.
Current maps from the CDFW placenutria hotspots in the Delta,
(06:45):
near rice production areas.
However, maps also show thatnutria is being spotted as far
north as Fairfield, which startsencroaching on the Sacramento
Valley rice production areas.
As the preferred habitat ofthese rodents is identical to
that of a rice field, thepotential for damages is high.
Additionally, identifying therice damage caused specifically
(07:08):
by nutria can be challenging, asit is easy to confuse it with
the damage caused by muskrats,as both rodents clip the stems
of the rice plants at thewaterline.
At high densities, nutria cansubstantially impact plant
communities.
In the U.S., rice is one of theprime However, nutria also favor
(07:31):
crops and plants that canneighbor rice fields, including
corn, grain sorghum, alfalfa,wheat, barley, oats, melons, and
a variety of vegetables fromhome gardens and farms.
When it comes to current methodsto try and control the spread of
nutria in California, CDFW iscollaborating with other
(07:53):
agencies and local partners todevelop the most effective
strategy for eradicating nutriafrom California.
CDFW believes that the currentstate of nutria population in
California indicates thateradication is possible if rapid
response is taken.
This is really good news,especially compared to other
(08:13):
states where eradication is nolonger a feasible goal, but
instead population control isthe attempt.
As an example, the nutriapopulation in Louisiana, where
the population control costs upto$2 million per year for bounty
harvest alone, is an indicationwhere eradication is not an
option.
(08:35):
In California, nutria areclassified as a non-game animal.
Fish and Game Code 4152specifies that property owners
or their agents who possesswritten permission from the
owner or tenant may take nutriaat any time by any legal means
to address damage to crops orproperty.
(08:56):
Restrictions apply to the use oftraps and the types of traps,
but this does indicate aterminal take, because nutria
are a restricted species inCalifornia under the California
Code of Regulations, Title 14,Sections and cannot be imported,
transported, or possessed livein the state of California.
(09:17):
In other states, bounty programsare underway to encourage the
taking of nutria.
However, in California, it isillegal to offer a bounty for
nutria.
California Fish and Game CodeSection 2019 clearly states, it
is unlawful for any person,including state, federal,
county, and city officials ortheir agents, to authorize,
(09:39):
offer, or or pay a bounty forany bird or mammal.
State legislation changes wouldhave to take place to alter the
code to provide an exemption fornutria.
Any nutria taken on private orpublic land should be reported
to CDFW as soon as possible forpurposes of delineating the
extent of the infestation.
(10:01):
At minimum, CDFW needs photos toconfirm identification.
Preferably, CDFW needs thecarcass to determine sex, age,
and reproductive status.
Suspected observations orpotential signs of nutrient
California should bephotographed and immediately
(10:21):
reported to CDFW online, byemail to
invasivesatwildlife.ca.gov, orby calling 866-440-9530, and
we'll have that informationlinked in the show notes.
Observations on state or federallands should be immediately
(10:41):
reported to local agency staff.
If this species is captured, donot release it.
Immediately contact your localCDFW office or county ag
commissioner.
Finally, to wrap up, I'mreaching out to you, our
listeners.
If you live in California andyou think you've seen a nutria,
(11:01):
let us know.
We're hoping to raise awarenessof this invasive pest in the
state.
Feel free to reach out throughany of the contact methods I'm
going to mention shortly.
(11:26):
We have a few upcoming events.
The UCCE Rice team will beholding a propanil stewardship
meeting.
And this will take place in twolocations on two different
dates, but it'll be the samemeeting.
And the first will be March 17thin Woodland at the Yolo County
(11:47):
Farm Bureau office.
And the second date will beMarch 18th in Richvale at the
Community Church.
We'll have the agenda and allother information up on our
resources, but that is still tobe announced.
So for more information aboutthese and other upcoming events,
feel free to check out ourresources, which include the UC
(12:07):
Rice blog and the UC AgronomyRice website.
In terms of other resources youmay want to take advantage of,
you can also look at our Thanksfor listening to Thoughts on
(12:38):
Rice, a University of CaliforniaCooperative Extension podcast
from the University ofCalifornia Agriculture and
Natural Resources.
You can find out more about thispodcast on our website,
thoughtsonrice.buzzsprout.com.
We'd love to hear from you,whether it's from using our text
link in the show notes, a surveysubmission in our feedback form,
(13:00):
also in the show notes, or in acomment or rating on your
podcast streaming service ofchoice.
We're also experimenting withpolls on Spotify, so if you're
listening on Spotify, you mayhave an option to answer some of
those questions, and we might beable to talk about that on air.
You can also email us with anycomments, questions, or concerns
(13:21):
at thoughtsonrice atucdavis.edu.
Spring has sprung for those ofus here in the Sac Valley, and
rice season is right around thecorner.
Remember, like the growers liketo say, Have a rice life.
Mention of an agrochemical doesnot constitute a recommendation,
(13:44):
merely the sharing of researchfindings.
Always follow the label.
The label is the law.
Find out more at ipm.ucanr.edu.
The views, thoughts, andopinions expressed are the
speaker's own and do notrepresent the views, thoughts,
and opinions of the Universityof California.
(14:04):
The material and informationpresented herein Thank you.
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