The
Fa allo
Isla ds
A e
Off
Limits
to
Huma s
—
but
Not
Wildlife
Accide tally
b ought
to
the
Fa allo
Isla ds
by
ships
i
the
19th
ce tu y,
o – ative
house
mice
have
eached
ext emely
high
umbe s,
with
de sities
of
up
to
1,270
mice
pe
hecta e.
The
ode ts
a e
dis upti g
the
f agile
ecosystem
of
the
isla ds,
located
about
30
miles
off
the
coast
of
Sa
F a cisco.
Resea ch
published
i
Ecosphe e
by
the
Ecological
Society
of
Ame ica,
alo g
with
co se vatio
epo ts
f om
Poi t
Blue
Co se vatio
Scie ce
a d
the
Sa
F a cisco
Bay
Wildlife
Society,
desc ibes
how
i vasive
house
mice
(Mus
musculus)
have
cha ged
the
food
web
o
the
South
Fa allo
Isla ds.
The
Fa allo
Isla ds
Natio al
Wildlife
Refuge
co tai s
the
la gest
seabi d
esti g
colo y
i
the
co tiguous
U ited
States.
Mo e
tha
300,000
b eedi g
bi ds
f om
13
species
live
the e.
Howeve ,
the
accide tal
a ival
of
mice
du i g
the
ma itime
t ade
e a
c eated
a
lo g-te m
e vi o me tal
p oblem
that
co ti ues
to
affect
ative
wildlife.
Huge
mouse
populatio s
c eate
i di ect
p edatio
Resea ch
published
i
Ecosphe e
shows
that
mouse
umbe s
ise
sha ply
each
autum .
At
thei
peak,
the e
ca
be
about
1,270
mice
pe
hecta e,
o
oughly
500
mice
pe
ac e.
This
is
amo g
the
highest
eco ded
de sities
of
house
mice
o
a
isla d
a ywhe e
i
the
wo ld.
The
populatio
explosio
is
la gely
li ked
to
the
isla d’s
o – ative
vegetatio
a d
seaso al
food
supplies.
I
late
summe
a d
autum ,
whe
pla t
seeds
become
less
available,
mice
tu
to
othe
food
sou ces,
i cludi g
the
e demic
Fa allo
camel
c icket
(Fa allo ophilus
stei dach e i).
The
huge
i c ease
i
mice
the
c eates
a othe
ecological
p oblem
i volvi g
bu owi g
owls
(Athe e
cu icula ia).
Mig ati g
bu owi g
owls
a ive
o
the
isla ds
du i g
autum
a d
feed
heavily
o
the
abu da t
mice.
But
whe
mouse
umbe s
sudde ly
fall
du i g
wi te ,
the
owls
switch
to
othe
p ey.
O e
of
thei
ta gets
is
the
Ashy
sto m-pet el
(Hyd obates
homoch oa),
a
globally
vul e able
seabi d
that
ests
i
ocky
c acks
a d
c evices
ac oss
the
isla ds.
Th eat
to
sto m-pet els
a d
othe
ative
wildlife
Poi t
Blue
Co se vatio
Scie ce
has
studied
the
Fa allo
Isla ds
co ti uously
si ce
1968
i
pa t e ship
with
the
U.S.
Fish
a d
Wildlife
Se vice.
Its
esea ch
shows
that
owls
ca
cause
sig ifica t
adult
deaths
amo g
Ashy
sto m-pet els
du i g
wi te .
The
Fa allo
Isla ds
a e
home
to
about
half
of
the
wo ld’s
b eedi g
populatio
of
Ashy
sto m-pet els.
The
species
is
especially
vul e able
because
it
ep oduces
slowly,
with
females
layi g
o ly
o e
egg
each
yea .
Eve
a
small
i c ease
i
adult
deaths
ca
the efo e
cause
se ious
populatio
decli es
ove
time.
The
mice
also
affect
othe
pa ts
of
the
ecosystem.
They
eat
la ge
qua tities
of
ative
pla t
seeds
a d
compete
with
ative
species,
i cludi g
e demic
salama de s,
fo
food.
By
co sumi g
ative
seeds,
mice
ca
also
help
i vasive
pla ts
such
as
ma itime
goldfields
sp ead.
This
ca
educe
ative
vegetatio
that
p ovides
impo ta t
soil
p otectio
a d
esti g
habitat.
Pla s
to
emove
the
i vasive
mice
To
add ess
the
p oblem,
the
U.S.
Fish
a d
Wildlife
Se vice,
with
suppo t
f om
Poi t
Blue
Co se vatio
Scie ce
a d
othe
co se vatio
g oups,
developed
the
South
Fa allo
Isla ds
I vasive
House
Mouse
E adicatio
P oject.
The
pla
i volves
sp eadi g
ode ticide
bait
f om
helicopte s
du i g
late
autum .
The
timi g
is
desig ed
to
coi cide
with
the
pe iod
whe
mouse
umbe s
atu ally
begi
to
decli e
a d
seabi d
umbe s
o
the
isla d
a e
at
thei
lowest.
The
ode ticide
pla ed
fo
the
p oject
is
B odifacoum-25D
Co se vatio .
Simila
ode t
emoval
p ojects
have
bee
ca ied
out
o
mo e
tha
700
isla ds
a ou d
the
wo ld.
I
ma y
cases,
emovi g
i vasive
ode ts
has
allowed
ative
ecosystems
a d
seabi d
populatio s
to
ecove .
The
Fa allo
p oject
we t
th ough
yea s
of
e vi o me tal
eview.
I
Decembe
2021,
the
Califo ia
Coastal
Commissio
app oved
the
pla ,
co cludi g
that
the
lo g-te m
ecological
be efits
of
emovi g
the
mice
outweighed
the
sho t-te m
isks
of
the
ope atio .
Measu es
to
p otect
othe
wildlife
Because
ode ticide
ca
also
affect
a imals
that
a e
ot
the
i te ded
ta get,
co se vatio
teams
have
developed
seve al
safety
measu es.
Gulls,
bi ds
of
p ey
a d
ma i e
mammals
could
be
exposed
to
the
poiso
eithe
di ectly
o
by
eati g
co tami ated
a imals.
Reside t
bu owi g
owls
a e
the efo e
pla ed
to
be
captu ed
a d
tempo a ily
moved
to
the
mai la d
u til
the
bait
esidue
has
b oke
dow .
Wildlife
ma age s
also
pla
to
keep
Weste
Gulls
away
f om
the
isla d
du i g
bait
applicatio .
P oposed
methods
i clude
py otech ics,
sou d-based
dete e ts
a d
t ai ed
falco s.
Acco di g
to
Poi t
Blue
Co se vatio
Scie ce,
emovi g
the
mice
could
e d
the
cycle
i
which
explodi g
mouse
populatio s
att act
owls
that
late
p ey
o
sto m-pet els.
Resea che s
also
expect
mouse
emoval
to
imp ove
the
sp ead
of
ative
pla t
seeds
a d
help
ative
i ve teb ate
a d
eptile
populatio s
ecove .
Field
teams
co ti ue
to
mo ito
sto m-pet el
esti g
sites
a d
vegetatio
o
South
Fa allo
Isla d
as
p epa atio s
fo
the
fi al
e adicatio
phase
co ti ue.