of Vildlife
Journal
DYNAMICS
OF PLAGUE
COMPLEX
Jack
FROM
F. Cully,
Jr.,12
IN A GUNNISON’S
NEW
Allan
33(4).
Diseaces.
© Wildlife
PRAIRIE
1997.
Disease
DOG
pp.
706-719
1997
Association
COLONY
MEXICO
M. Barnes,34
Thomas
J. Quan,3
Maupin3
Gary
and
Museum
of Southwestern
Biology,
Department
of Biology,
University
of New Mexico,
Albuquerque,
New Mexico
87131,
USA
2 Present
address:
USGS,
Biological
Resources
Division,
Kansas
Cooperative
Fish and Wildlife
Research
Unit,
204 Leasure
Hall, Kansas
State University,
Manhattan,
Kansas
66506,
USA
Plague
Section,
Bacterial
Zoonoses
Branch,
Division
of Vector-borne
Infectious
Diseases,
Centers
For Disease
Control
and Prevention,
Fort Collins,
Colorado
80522-2087,
USA
Deceased
1
(Yersinia
pestis)
epizootic
spread
through
Gunnison’s
prairie
dogs
(Cynoinys
possibly
other rodent
species,
in the Moreno
Valley
in north-central
New
Mexico
between
winter
1984-1985
and autumn
1987.
We observed
the progress
of the epizootic
and
subsequent
population
recovery
at four
prairie
dog towns
within
the valley during
this period.
At
two towns
(Midlake
and Val Verde)
the prairie
dogs
were
marked
prior
to the epizootic.
At two
A plague
ABSTRACT:
and
gunnisoni),
additional
In 1988,
collected
burrows.
towns
(Vega
and
South
Entrance)
prairie
dogs were
marked
following
the epizootic.
a second
epizootic
occurred
at Vega.
One
hundred
thirty-nine
serum
samples
were
from
prairie
dogs
and other
rodents
and 1,750
fleas were
collected
from
animals
and
Fleas
infected
with
1’. pestis
were
collected
from
prairie
dogs,
deer
mice
(Peromyscns
maniculatus),
and thirteen-lined
ground
squirrels
(Spermophilus
tridecemlineatus).
Prairie
dog
fleas
included
Oropsylla
hirsuta,
0. labis
and
0.
tuberculata;
deermouse
associated
fleas were
Aetheca
wagner!
and
Rhadinopsylla
sectilis,
and Oropsylla
bacchi
was associated
with
thirteenlined
ground
squirrels.
All of the
above
flea species
were
collected
from
prairie
dog burrows.
All
rodent
plague
epizootic
Vega
dog
some
in
mortality
that
at
more
plague
became
in
summer
all
ground
than
dogs
abundant
1988.
of the
few
plague
prairie
in
1987,
and disappeared
we collected
serum
was
dogs
left
in
words:
Key
Cynornys
Yersinia
dynamics,
Plague
(Yersinia
in
New
gunnisoni,
pestis.
prairie
epizootiology,
in
1982
had
been
found
infected
1978).
Moreno
Plague
prairie
reported
excess
of
99%.
disappeared
were
at the
rare
time
from
(Microtus
prairie
Serum
colonies
fleas,
shortly
following
the
of the second
Gunnison’s
prairie
pennsylvanicns),
dogs.
antibody
Prairie
titers
following
with
it
was
(Link,
further
observations
1983
when
a teen-age
of Eagle
Nest
(NM)
interspecific
disease
and
Improvement
discov-
Fe, NM,
dog
and
the town
positive
in Gunis
by
ciate
of 33 coun-
dog
indicate
epizootics
survived
Y.
nopsylla
pestis
found
1955).
(Weber,
in the
in Auwere
sectilLs,
ceptible
study
a deer
flea
prairie
to
the
terrupted
al., 1962;
706
ground
species
dogs,
squirrels
0.
hirassociated
and
Rhadi-
mouse
(NMEID,
(Peromysunpub-
records).
Gunnison’s
of plague
there
until
boy from
the town
became
ill with
the
pop-
Environmental
(NMEID,
Santa
tridecemlineatus),
and
0. labis,
flea
Gunnison’s
prairie
lished
no
NM
thirteen-lined
snaniculatus)
in Gunnison’s
There
The
Division
plague,
USA)
collected
fleas from
prairie
ground
squirrel
burrows
around
of Eagle
Nest
and found
Y. pestLs
Oropsylla
bacchi,
fleas
that
asso-
with
suta
with
transmission,
died.
(Spermophilus
NM,
21 species
of
of fleas have
been
was
first
recorded
Colfax
County,
NM,
when
dogs
first
USA)
in 31
1982).
In
16 species
Valley,
1949
was
(NM;
dogs
(Cynomys
gunnisoni)
1938
(Link,
1955).
Plague
throughout
the state,
and
Zuni
found
ties (Barnes,
rodents
and
pestis)
Mexico
near
now
gust
voles
meadow
voles
only in Gunnison’s
to establish
INTRODUCTION
nison’s
Meadow
infection.
ulation
ered
squirrels
Midlake.
mice,
and
Y. pestis
against
by
ground
at
Although
deer
titers
affected
40%
prairie
squirrels,
serum
towns
Thirteen-lined
species.
in
1986,
epizootic
thirteen-lined
identified
elevated
we
flea
identified
was
at
prairie
dogs,
shared
species
before
plague,
dogs
and
are
highly
sus-
three
attempts
to
species’
social
behavior
were
inby the
disease
(Lechleitner
et
1968;
Fitzgerald,
1970;
Rayor,
CULLY
1985).
Mortality
in Gunnison’s
as
a result
of
l)ut
those
reports
of
cover>’
ET AL-PLAGUE
plague
prairie
prairie
populations
(luent
to plague.
In this paper,
a wave-like
plague
epizootic
through
prairie
a 100 km2
dog
towns
NM,
between
1987;
we
covery
also
of
to
attempt
plague
1985
the
dog
and
epizootic.
disease
interspecific
the
in
Autumn
we describe
that
swept
IEU Summer
course
dynamics
both
re-
1986
EJ
km2.
100
cattle
The
land
#{149}o
2,560
Cattle
because
daily
temperatures
warmest
m,
Forest
month
of
usually
occurs
of
the
winter
18
C.
during
privately
owned
grazing
State
snow
also
The
July
heaviest
and
precipitation
August
Climatologist,
is
(NM
1984),
important
#{149}0
ley
Creek
Nest
town
geographic
to
bound
the
flows
features
in
plague-affected
east
from
Lake,
approximately
of Eagle
Nest
(Fig.
SE
123
404k
4040
#{149}400
4000
“
the
the
range
Moreno
areas.
0404
444
04444
2
400
II
#{149}
Ii
444
IIII
440
44
II
IIII
O
44
*440
I
64
440,
044
64
1.
FIGURE
the
=
locations
South
NIap
Entrance,
044 04
of
of the
the
study
\‘V
444
004
444
Moreno
areas
(ML
\‘al Verde),
period
March
=
Valley
=
and
0440640 6 0
showing
SE
Midlake.
the
progress
of plague
(luring
the
1985 to Novem1)er 1986.
Plague
probably
began
in prairie
(logs
north and east of Eagle Nest during
the summer
of
1983. The shading
shows
the course
of plague
(hiring
the period
winter
1985-summer
1987. The three
regions
were
separate(l
h
1)olmndaries
at Six-mile
Creek
(I) and Jackson
Hill (2).
Of-
although
veg-
etation.
Two
04404
4644
4404
KM
is lo-
winters
perature
fice
mostly
ML
406
4004
400
is limited
to sumare very cold with
mean
of -5
C in January.
The
is July
with
a mean
daily
tem-
ranches.
mers
is
4044
4044
#{149}
,#{149}
elevation
46
44
44
1
the
cated
in
the
Sangre
de Cristo
Mountains
(:36#{176}:30’N,105#{176}15’W) Colfax
County,
NM (Fig.
1). The bottom
of the Moreno
Valley
supports
a variety
of grasses
and shrubs;
plant
cover
and
productivit
are high.
Suitable
prairie
dog habitat
in the Moreno
Valley
covers
approximately
446
.
__)
6040
44
4*0
Roads
Valley.
Valley,
est
444-’VEG
444
METHODS
Moreno
040
0444
604
4444
34,4
,/
44
The
0444
04444
04406
004*
Dirt Roads
-
of the
intraspeof
0 40444*
/3
0044
4400
1985
\
707
/
0o,0
#{149}
Trap Site
we
transmission
4,,,:/
4000400
0444
04
44
46
sub-
Additionally,
Moreno
esoo#{149}
Paved
of
DYNAMICS
Eagle
summer
populations
to analyze
the
epizootic,
including
cific
POPULATION
of plague
subse-
and
the
prairie
DOG
Spring 1985
of Gunnison’s
Moreno
Valley,
document
the
sequent
complex
in the
spring
Time
PRAIRIE
been
not
dog
dogs
GUNNISON’S
described,
followed
the re-
has
have
AND
Val-
Six-mile
the
forest
into
Eagle
4 km south
of the
1). The valley
formed
by this
stream
contains
mesic
grassland
with
the
water
table
close
to the surface.
Prairie
dogs
did not dig burrows
in this habitat,
and
the
rarely
ventured
into
it more
than
5 to 10
ni. The
grass
was usually
high
enough
to obstruct
a prairie
dog’s view
of its surroundings.
The second
boundary
was Jackson
Hill, a ridge
that
crosses
the
valley
approximately
7 km
south
of Six-mile
Creek.
The
ridge
is covered
by shallow
soil and
xeric
grassland
similar
to
that
of uplands
throughout
the valley.
Prairie
dog colonies
were
present
both north
and south
of Jackson
Hill, hut were
separated
by approxiniately
1 km.
The
first
study
area
(Midlake)
was located
adjacent
to Eagle
Nest
Lake
in October
1984,
and
consisted
dog
town
of 9 ha
in the
that covered
1). The Val Verde
(Fig.
the south
end
Both
were
middle
of a prairie
approximately
100
site was identified
ha
at
the valley
in October
1985.
established
in advance
of the
plague
epizootic.
After
plague
eliminated
prairie dogs
at Midlake,
the Vega
study
site was
established
in March
1986,
at the north
end of
the valley
2 km west of the town of Eagle
Nest,
and
sites
South
of
Entrance
was
identified
in
June
1987,
near
the south
end of Eagle
Nest
Lake
approximately
2 km south
of the original
Midlake study
site.
Prairie
dogs
were
trapped
in small
Tomahawk
live traps
(14 X 14 X 40 cm) baited
with
rolled
oats.
When
captured,
prairie
dogs
were
weighed
on a triple
beam
balance,
sexed,
aged
to juvenile
or adult
age class
by weight
and
pel-
age color
(Cully,
1997),
uniquely
marked
by toe
clip or numbered
fingerling
tags attached
to the
ear, and individually
marked
with
commercial
hair dye. We attempted
to trap all of the prairie
dogs
at the study
sites.
Visual
observations
of
708
JOURNAL
OF WILDLIFE
DISEASES,
VOL.
33, NO. 4, OCTOBER
marks
combined
with
recaptures
in
indicated
that
more
than
90%
of prairie
at the staked
study
sites
at Midlake,
Vega
South
Entrance
were
marked.
At Val Verde
proximately
50% of the active
prairie
dogs
captured
on the
1 ha area
trapped.
Mark
capture
trapping
was inappropriate
during
ulation
declines
because
the high rates
of
tality
would
bias the analysis.
In 1988
at Vega,
South
Entrance,
and
fur
Verde,
prairie
dog
populations
were
traps
dogs
and
apwere
repopmorVal
estimated
1997
groups
of prairie
the same vial for
Disease
Control
sion of Vector-borne
Collins,
Colorado,
and analyzed
for
In the laboratory,
amined
microscopically
and
identified
to species following
the classification
of Traub
et al.
(1983)
or Hopkins
and Rothschild
(1962).
After
identification,
and Biggins,
1986;
Menkens
and Anderson,
1993).
At Vega
and
South
Entrance,
2 ha plots
were
marked
with wood
stakes;
the grids
were
100
X 200
m
with stakes
placed
at 20 m intervals.
The stakes
made
it possible
to systematically
count
prairie
dogs
on areas
of known
size
during
periods
site,
cies.
when
6-wk-old
days
of
by
visual
scan
it
was
counts
not
(Fagerstone
possible
to
trap
animals
or
when
Visual
the
populations
were
changing
rapidly.
counts
were
made
from
a car parked
approximately
100
m from
the prairie
dog towns.
Counts
were
made
with
the aid of lox
binoculars
and
a 3O
spotting
scope
three
or four
times
in the
morning
while
prairie
dogs
were
most
active
above
ground.
The
highest
count
was used
for the population
or density
estimate.
During
1985,
blood
samples
were
collected
from
toes
when
the animals
were
marked
by
toe clipping.
This
method
was satisfactory
only
during
warm
weather
when
the wounds
bled
freely.
Consequently,
beginning
in April
1986,
blood
samples
were
collected
by cardiac
puncture.
Newly
captured
animals
were
anesthetized
with
ether
to reduce
stress
during
handling,
and to simplify
collecting
fleas which
also
were
anesthetized
tested
for
antibodies
by
the
ether.
All
to Y.
pestis
using
sera
were
the pasHealth
Or1:16 were
test
(World
1970).
Sera
with titers
considered
positive.
Beginning
in July
1985,
fleas and blood
samples were
collected
from
newly
captured
prairie dogs.
Fleas
were
brushed
from
the anesthetized
animals
during
the handling
procedure.
Fleas
also were
collected
from
prairie
dog burrows by swabbing
the burrows
with a square
of
flannel
attached
to the end
of a sewer
cable.
The
swab
was inserted
1 to 2 m into burrows.
Fleas
were
immediately
removed
with
forceps
and
placed
in a 2% NaCl
solution
in a small
vial. If no fleas
were
captured
on the first swab,
another
burrow
was selected.
If the swab
collected
fleas,
the burrow
was swabbed
repeatedly
until
fleas were
no longer
captured.
Burrows
were
selected
from
throughout
the
marked
portions
of the study
sites,
and represent
a cross
section
of the burrows
in the colony.
Fleas
from
burrows
that
were
close
together
and shared
by individuals
within
social
sive
hemagglutination
ganization,
dogs were often combined
in
submission
to the Centers
for
(CDC,
Plague
Branch,
DiviInfectious
Diseases,
Ft.
USA).
Fleas were identified
1’. pestis
at CDC.
fleas were individually
ex-
fleas
were
host species
(or
Fleas
collected
social
pooled
by
collection
group),
and
from
different
flea
spesocial
groups
or towns
were
kept
separate
as described
above.
Flea pool size never
exceeded
25 individuals.
Flea pools were triturated
in a
small amount
of physiological
saline and 0.1 ml
aliquots
were
inoculated
subcutaneously
into
and
mice.
The
inoculation
spleen
logical
tissues
analysis
cause
of
mice
were
that
died
necropsied
within
and
21
liver
were
to
death
removed
for bacteriothat plague
was the
described
by Quan
et al.
verify
as
(1981).
Rodents
other
than
prairie
dogs
were
trapped
at Midlake,
Val Verde,
and Vega to determine
which species
were present
and to collect fleas and serum
samples
for plague
analysis. Small
rodents
were
trapped
at study
areas
on three
or more
occasions
between
September 1985
and September
1988.
Folding
aluminum
8 x 9 x 23 cm Sherman
Live Traps
were set in parallel
rows of 10 with 10 in between
traps. The number
of rows set varied between
trap sessions
at the three
areas.
Traps
were baited
each evening
and examined
in early morning
and at least two times
during
the
day. Because
of high mortality
during
blood
collection,
(blood was collected
from these species by cardiac
puncture
in order
to obtain
adequate
sized
samples
for antibody
analysis),
mark-recapture
population
estimation
was not
appropriate
for deer mice and meadow
voles
(Microtus
pennsylvanicus).
Relative
population
estimates,
fort, were
based
on
calculated.
captures
per
trap-night
ef-
RESULTS
Plague
occurred
between
in
autumn
(Table
1, Fig.
1).
in three
spatially
phases.
killed
In
valley
gle
Nest
(Fig.
1).
Moreno
and
The
and
dogs
west
of
Valley
summer
epizootic
temporally
winter-spring
prairie
the
the
1984
1987
occurred
distinct
1985,
in the
northern
Moreno
Creek
Lake,
north
of
Six-mile
From
July
1985
to
plaguethird
and
of
Ea-
Creek
July
1986
CULLY
ET AL-PLAGUE
AND
‘
GUNNISON’S
PRAIRIE
s
DOG
POPULATION
DYNAMICS
709
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710
JOURNAL
TsBI.E
2.
OF WILDLIFE
Results
of
DISEASES,
1)100(1
samples
VOL.
collected
Area
NIidlake
from
Area
Stud
Cjnmnys
mammals
at
the
Moreno
Verde
Gynonijs
3
2
12
13
1
4
1
15 (2)
tridecemlineatus
pennsyh)anzcus
Ctjnoinys
gunnzsoni
of sainph’s
analyzed.
of
with
aultih(xlies
prairie
dogs
samples
plague-killed
valley
Underline
between
Jackson
Hill.
June
1986 and
Hill.
There
was
:3
99 (2)
I
in the
Six-mile
pesti.s
samples
were
in parentheses.
middle
of
Creek
and
Plague
occurred
July 1987,
south
between
of Jackson
no
plague
of
collected
declined
third
of
during
similarly
the valley.
throughout
At the
One
litter
of
three
juveniles
adult
200 m south
on 14 June
1986.
was
captured,
but
tober
1984.
The density
estimate
trapping
at Midlake
in October
positive
for Y. pestis.
were
no longer
any
and
1985,
been
from
on
was
On
in July
1985,
was
28/ha.
an adult
in the
male
trap
died
for
in a trap.
He
<2
hr when
24
burrows
ples
ples
dogs
first
et
1’.
al.
1981).
pestis
fleas were
collected
from
burrows
lake
(see below).
By September
ulation
had
declined
noticeably,
On
6
positive
at Midthe popand
by
early
October
1985,
approximately
25 prairie dogs
remained
where
168 had
been
marked.
At the same
time
the population
a single
the
juveniles
were
On 5 July 1986,
there
prairie
dogs
at Mid-
and eight
Y pestis
were
collected
in
laboratory
(Quan
flea
by
and
lake.
bles 2, 3) from
Val Verde.
The
the
central
study
all that
remained
of these
animals
samples
collected
None
used
tive for Y. pestis;
however,
Gunnison’s
prairie dogs
die so quickly
from
plague
that
they
may fail to develop
measurable
antibodies
before
death;
this also is true
for
mice
were
There
were
no indications
the
south
end
of the
valley
1986.
Three
antibody
negative
found,
and at that time
he was moribund.
Two hr later
he was dead.
A blood
sample
obtained
from
this animal
was sero-nega-
1985,
the
Midlake
area
only
7 to 10 animals
emerged
from
hibernation
in April
1986, where
there
had
been
approximately
90 one
year
earlier.
in
based
1984,
:32 (4)
epizootic.
prairie
dogs in the middle
of the valley
until July 1985.
Visual
observations
indicated
that the density
of Gunnison’s
prairie
dogs
was
similar
throughout
the valley
in Oc-
30/ha,
9
5 (2)
that
indicates
against
evidence
16
tridecem!ineatus
8
Number
4
I
Total
b Number
(2)1)
1
4
maniculatus
Microtus
Spermophilus
August
23
gunnzsonz
Peronnjscus
July
had
1
2
pennsylvanicus
Sperinophilus
the
1
inaniculatus
Microtu,s
1987
4
tridecernlineatus
Peroini,scus
USA).
7
5S
gunnzsonz
Mexico,
1986
maniculatus
Spermophilus
Entrance
(New
tridecemlineatus
(7ijnomys
Vega
Valley
1985
gunnisoni
Peromijscus
South
1997
Species
Spennophilus
Val
33, NO. 4, OCTOBER
disappeared
to US
negative
October
flea
1985
sam(Ta-
18 prairie
dogs
trapped
first indication
of plague
the south
end
of the
tween
1 and
14 June
cent
of plague
at
until
June
serum
sam-
valley
1986,
from
Highway
at
at
occurred
bewhen
prairie
a 2 ha
field
adja-
64 at Val Verde.
From
4 to 6 July
1986,
30 prairie
dogs
were
trapped
and
marked
at a 1 ha area
near
the center
of the Val Verde
Town.
Visual
counts
of
marked
and
at
the
trap
area
indicated
of
the
prairie
dogs
unmarked
were
that
marked
animals
about
half
so
the
CULLY
3.
Tutl.t:
Fleas
from
ET AL-PLAGUE
Gumnnison’s
prairie
Number
AND
clog
GUNNISON’S
burrows
PRAIRIE
in the
Moreno
DOG
Valley
POPULATION
(New
DYNAMICS
Mexico,
711
USA).
of
Inirrosvs/nomber
Area
Nlidlake
Val
sampled
Year’
Verde
16/78’
56
(6/10)d
18
1986
12141’
58
(2/6)
22
1987
4/25
1985
7/21
20/59
1987
South
Entrance
Underline
Oil
indicates
.et/u’ea
fleas
population
50 per
10,000
tested
ii
96
1987
2/25
plague
collected.
but
( miumnber
pestis.
By
11 August
a massive
dogs
There
die-off
remained
were
town
was
highest
tion
was
eral
area.
prairie
in pramfle
OTC
=
the
number
of
plague
positive
dogs
town
at the
where
in
mid-summer,
dogs
all were
duration
end
of
there
burrows
been
colony.
across
valley
more
occurred
between
deep
grass
dogs.
By
were
was
than
8
no active
of the Val
had
been
the
popula-
at the
1987,
we
the center
nulliparous
of the epizootic
However,
1(1/1)
2
periph-
trapped
of the
four
town
adult
females.
at the south
approximately
90%
of the
July
and
1 yr.
mortality
11 August
8 (3/3)
2 (212)
4 (1/2)
7
7
6
(logs.
tu/wrculaia
without
pools/total
5 prairie
of the
dogs
and
from
and
The
had
with
prairie
reduced
July
(3/11)
Oropsylla
collectfor Y.
4 to
central
areas
densities
noticeably
In
there
only
center
prairie
1986,
the
(5/6)
a concentration
of approxia ridge
400
m to the northseparated
from
the rest of
mid-September
prairie
Verde
active
Fleas
were
not assayed
by mesic
habitat
little
used
by
1
77(1/6)
blood
samples
negative
anti-
1986,
and
at the
scattered
the town,
and
mately
100 on
west
that
was
1986.
of
prairie
dogs.
Four
from
that
time
had
body
titers
to Y. pestis.
ed and
identified,
but
the
that
was
01. = Oropsylla
labis,
Caiallagia
rleezp:ens.
were
CD1’
4
4/25
collected
A\V1’
79
15/25
=
(2/6)
143
109(1/3)
1988
when
OB1’
I
(2/19)
at that time
was approximately
The
colony
covered
approxiha and
consisted
of 5,000-
ha.
200
mately
18
235
1987
CI)
samples
of
Number
1/25
15/108
year
wagnm’rm.
Additional
1988
OTG1’
13
12/35’
1986
/iirsuta,
()ropsujlla
=
01.1
1985
198(1
Vega
0111
number
eynomuns.
wa.s
fleas
of
miot
OB
Oropsylla
=
A\V
and
May
=
recorde(l.
pls
Between
September
1987,
the Gunnison’s
tion
in the
Moreno
from
more
tween
250
imum
than
mortality
and
1984
prairie
Valley
dog
was
100,000
500.
rate
1986
north
At
and
end
lined
traps
ground
without
animals
of 99.5%.
their
density
This
epizootic
mor-
at
1984,
noting
frequently
that
captured
dogs.
During
spring
1985,
teen-lined
ground
squirrels
Midlake
be-
a min-
the
thirteen-
were
released
from
so we cannot
estimate
beyond
as
to
because
the
born
during
1987,
after
the
of the valley.
Midlake
in October
squirrels
marks,
populareduced
represents
This
tality
estimate
is conservative
survivors
included
animals
nearly
bare/mi,
compared
to
they
as
only
thirat
three
were
77
were
prairie
caught
prairie
dogs.
Thirteen-lined
ground
squirrels
disappeared
from
Midlake
by the end
of June
1985,
but whether
they
had plague
is not
known.
Limited
trapping
at Midlake
indicated
that
there
October
was
the
deer
mouse
high
(0.12/trap
1985,
at the peak
dog
epizootic
one
meadow
(Table
vole
negative
antibody
trapped.
In
later
4).
Also
without
titer
trap
population
night)
of the
at that
fleas
to
during
prairie
1.
sessions
and
time,
with
a
pestis
was
the
deer
712
JOURNAL
TABLE
4.
OF WILDLIFE
Results
DISEASES,
of live-trappimsg
VOL.
(leer
33, NO. 4, OCTOBER
mice
and
meadow
1997
voles
Peronmyscu
Midlake
Val
Trap
Year’
Area
Verde
nights
1985
200
1986
120
1987
80
1985
1986
April
Vega
1986
September
Underline
mouse
half
voles
At Val
dropped
Verde,
teen-lined
ceded
the
to
in October
captured
0
0.0667
8
0.0400
120
0
1
0.0083
80
0
active
night,
the
no
4).
in thir-
local
prairie
after
growth
population
at
October
1987.
Voles
were
first captured
at
Val Verde
in August
1986,
and were
still
present
there
in 1987
(Table
4).
Rodents
other
than
prairie
dogs
were
not trapped
at Vega
until
1986,
1 yr after
dogs
common.
Later
that
lation
increased
and
1987.
In September
rie dogs disappeared
ulation
were
was
present
August
1987
The
varied
cases
tionship
and
and
population
species
most
again
at
September
subsequent
was
the
in
of the
area
no
time.
predictable
number
plague
different
over
of
In
rela-
rodents
phenology
at
in
disappearance
1988;
of
thirteen-lined
to
the
(2)
the
ground
prairie
and
of
and
dog
plague
concurrent
with
prairie
dogs
(six
from
thirteen-lined
from
26
squirrels
mice
(zero
(zero
positive),
positive),
and
(zero
were
positive;
before,
positive
prairie
1986,
and two
1987,
had titers
of
samples
from
South
May 1987,
had titers
were
were
of 15 post-epizootic
while
at South
positive
positive.
One
thousand
were
collected
(Table
lined
deer
2).
and
Although
during,
and
sera
the
were
colepizootic.
all positive
more
after
April
antibody
ground
20
from
deer
30 from
meadow
Table
collected
epizootic,
1 yr or
Two
two
itive
mice
1988.
densities
there
and
un-
the
the
vole
ters,
61
positive),
sera
year
the vole
popustayed
high
through
1988,
when
the praiat Vega,
the vole pop-
low (Table
4). Deer
Vega
in low numbers
at each
between
the
dogs.
In March
deer
mice
were
to
and
of the
at Vega in 1988.
thirty-nine
serum
samples
and tested
for antibody
ti-
ter the
lected
pearance
of the prairie
April
1986,
voles
and
to
epizootic
One hundred
were
collected
bers
disap-
decline
Midlake,
the
voles
the
Exceptions
epizootic,
at Vega
disappearance
the plague
epizootic
there.
Thirteen-lined
ground
squirrels
were
present
in low numdis-
plague
prior
epizootic
with
0.0167
towns.
subsequent
curred.
At the south
end
mouse
populations
were
throughout
the
period
of the valley,
deer
consistently
low
October
1985
to
dog
the
and
prior
simultaneously
0.0661
this generalization
were:
(1) the absence
of
voles
in the meadow
near
Vega
in Spring
1986
prebut
they
0.4 125
37
5
squirrels
when
33
clogs.
in prairie
change
0.0107
prairie
appeared
0.0050
0.0750
1985,
and
there
(Table
1988,
night
6
squirrel
numbers
in prairie
dogs,
summer
trap
24
since
little
trapping
occurred
there
prior
to June
1986,
it is unlikely
that
we could
have
detected
a reduction
if one had oc-
until
pennsylvanicmis
Per
1
USA).
80
0.5/trap
no obvious
ground
epizootic
Mexico,
Captures
0
0
that
were
night
0.0500
300
density
<one
more
trap
0.1150
1988
was
Microtus
6
6
plague
Per
(New
360
1986
when
Valley
23
560
ear
Moreno
s maniculatus
Captures
1987
indicates
in the
af-
dog sera from
Vega in
from
Val Verde
in July
1:256;
the two positive
Entrance
taken
in
of 1:128.
At Vega only
samples
Entrance
at Val
were
postwo of five
Verde
seven
hundred
from
prairie
dogs
two
of two
fleas
burrows
fifty
3), prairie
dogs
(Table
5), thirteenground
squirrels,
meadow
voles,
and
mice
(Table
6). The
highest
number
CULLY
5.
TxBI.I.:
Nuumrmber
of fleas
Area
Midlake
Val
Verde
ET AL-PLAGUE
collected
Emutrance
Oil
15
6
12 (1/3Y1
3
1985
8/8
63
1986
19/30”
1987
1/1
fleas/miuimmiber
Iunlicatel
of fleas taken
a prairie
dog
prior
to the
number
row
at
after
pools
dogs;
one
(4%),
the
epizootic
ble
5).
rows
1.4)
SD
=
fleas.
at
26.7)
=
SD
at
without
and
6.
37
Numnsber
Spennopimilus
.fiC’I’u)tu15
=
=
not
tele/,inu.s.
CN
imum
were
of fleas
collected
=
Catallagia
1
Orop.sqlla
=
hare/mi.
RS
=
(Ta-
bacchi,
bur-
and
bur-
the
(n
rows
29,
Midlake
EW’
Oil
=
8
37
1
Oropsylla
()ropsylla
?aeweyi.
32
CD
=
litter
were
Catallagia
other
OIl
0.
(n
38
=
for
and
than
prairie
OL
OTC
OB
2
6
2
98
2
2
clogs
OS
On
from
three
An additional
of
prairie
hirsuta
RS
01.
=
=
Oropstlla
R/iathimopsylla
(/m’ci/)iens.
lahis.
seetilis.
MAB
=
OTC
A’s’
dogs
was
1986,
one
dogs
present
which
at
we
Mid-
A\’
MT
(:N
4
1
1
64
10
.fegahot/mrzs
Oropstlla
=
=
.%et/ieea
ahanti.s.
16
18
14 June
Moreno
1
at
1985,
in the
6
3
Y
bur-
September
prairie
trap
was
RS
hirsuta,
collected
from
four
pooi
of 0.
for Y. pestis.
burrows),
0.
prairie
dog
the epizootic
collected
examined.
of juvenile
unable
to
spe-
1) for
for 0.
(n
burrows)
August
min-
flea
6 burrows)
positive
fleas
from
at Midlake.
During
in
pools
The
among
100%
labis
58
=
most
flea.
Valley
(New
Mexico,
(:1)
SlAB
MAS
5
2
/mirsvaa.
stanforils.
for
(n
positive
The
rodents
and
one
rates
fleas were
collected
in 1986,
and one
regularly
collected
from
infection
21 fleas
were
prairie
dogs
samples
of burrows
positive.
than
most
abundant
flea species.
On 6 August
1985,
NMEID
31,
2:3
=
3%
=
(n
positive
4%
pestis
5.0
pool
positive
fleas
was
of positive
pools
flea would
make
cies in burrows
varied:
A. wagneri,
9% (n =
SD
ii
OS
OB
of more
field
2,
pools
(41%)
ueenunan:,
bare/mi.
1
of pools).
entire
3.9
counted
Ninety
the
during
flea
/)t’lm?isi/ltiI?lit’US
I’/)itU/(’(1
1
4
eynoinuris.
consisted
were
number
inanzculatus
()rop.sylla
tuberculata
4 (n =
17.3
(n
and
tndt’ceinlin’u’itus
ont/sc’us
27
percentage
of Y pestis
lower
than
the number
because
a single
positive
flea
prairie
infested
Species
Pets
Oropsylla
dog burrows
during
or followwere
analyzed
for Y pestis,
of these
Tsni.t:
USA).
7
1 yr
censused
Other
the
were
from
prairie
ing epizootics
2
=
Y. pestis
fleas
Verde,
1986.
June
370
of
but
fleas
until
2
a bur-
Midlake
Among
Vega.
collected,
1’
4
25 from
1985,
highest
1987,
for
at Midlake,
Entrance,
at Val
5.9)
were
at
of
2.6)
South
1
3
fur plague.
from
June
positive
numbers
SD
MVt’
1
1)ools/total number
assavel
not
98
30
hundred
mean
8,
=
were
was
taken
contained
RS”
:3
6
OT(:
Twenty-seven
directly
from
was
One
rows,
1986
on
epizootic.
collected
USA).
exaumuinecI.
Verde
the
were
Mexico,
OB”
59
(miuimiilwrof phugume positive
burrows
Val
(New
713
Ui5011.
from
any animal
was
at Val Verde
in October
epizootic
there.
The
from
\‘allev
DYNAMICS
active.
lahis.
Oropsujlla
=
July
from
was
.‘tfmflmOJ)syll(l
=
80
18
plague
Moreno
126
5
collected
saoiples
P/21
POPULATION
OTC”
9
27”
6
9/4:3
01.
Nuimmiber
40”
1:3/1:3
54
ml which
/iirsuta,
r of hosts
DOG
01,1
4/4
‘a’’tilis.N1\’
with
011k’
in the
3/16’
Ii/maI:uimsylla
1 Nummumber of flt.as
clogs
1986
ear
()ropsylla
=
prairie
1985
1987
indicates
Umiclerlimie
Guinmsisoms’s
PRAIRIE
Nuimnbc
1987
South
from
GUNNISON’S
Year’
1986
Vega
AND
tU/E’I5’Ulata
MAS
=
OB
‘ym)muns.
MT
uagm’ri.
26
=
.fegahmt/arz.s
,falaram’us
asso.
714
JOURNAL
lake.
rows
We collected
they
were
were
positive
suta,
two
bacchi.
At
OF WILDLIFE
DISEASES,
66
using;
six
Midlake
labis
four
and
mouse
flea
(Table
at
mice
labis,
a species
rie
clogs
(Table
On
eight
prairie
Only
fleas
one
and
it
24 fleas,
one
were
Verde
on
14 June
blood
samples
July.
Ten
June
July
were
1986,
from
flea
fleas
1986,
and
prairie
pools
taken
at the
beginning
per
host
was
flea
species
prai-
and
6 to 7
burrows
in
Verde
in
sampled
epizootic
suta,
gust,
0.
the
labis,
prairie
ter of Val
flea pools
center
were
the
and
0. bacchi.
dog population
By
at the
Verde
had crashed.
Five
collected
from
burrows
of the
town
on 12 August
positive
for Y. pestis.
Prairie
small
satellite
by mesic
habitat
Verde
town
was
collected
there
on
ative
for
10 pools
colony
that
was
Au-
cenof 18
at the
1986,
dogs
at
isolated
from
the rest of the
still at high
density.
Val
We
five
flea
pools
from
burrows
13 August
1986,
and all were
negY. pestis.
In June
1987,
three
of
from
prairie
dog burrows
at the
center
of the town,
including
0. labis,
and A. wagneri
were
Y pestis.
Deer
11
mice,
meadow
squirrels
were
voles,
lined
Verde.
ground
There
voles.
were
though
Thirteen-lined
ground
mostly
infested
with
0.
they
also
carried
two
no
0. hirsuta,
positive
for
and
thirteen-
were
trapped
at Val
fleas
on meadow
squirrels
bacchi,
species
alof
dogs in spring
Y. pestis.
The
mice
fleas.
3.6
eight
from
1986.
mean
14
All were
number
(range
0-18,
present
captured
However,
fleas
in
3).
prairie
samples
dog
0.
from
bacchi,
and
tis
hirsuta;
wenniani
We
Vega
the
Catallagia
fleas
only
three
neweyi.
at Vega.
vole
M.
at
did
we
Thirteen-lined
parent
(mean
=
2.2 fleas/prairie
dog,
SD = 2.5,
range
0-8).
Fleas
collected
in July were
identified
to species
but were
not checked
for plague.
Those
samples
included
0. hir-
with
on
SD
prairie
dogs
at Vega were
0. hirsuta,
0. labis,
0.
tuberculata
cynomuris,
Pthadinopsylla
sectilis, and Ceratophyllus
vison;
the last two
species
are deer
mouse
fleas
(Haas
et al.,
1973).
Deer
Y. pesat Val
on
=
of fleas
collected
The
was
fleas.
one
flea
of the
diversity
4.9).
took
from
highest
(Table
6).
Vega,
fleas
were
of fleas
for
fleas
not infected.
At Val
30 prairie
dogs
were
the
vole
on
dogs
had
adult
prairie
negative
for
had
no
including
negative
for
prairie
dog flea,
0. hirsuta
and
0. labis,
and A. wagneri,
a deer
mouse
flea (Table
5; Thomas,
1988).
Deer
mice
at Val Verde
species
At
6).
All were
burrows
1997
squirrels
one deer
found
typically
0.
24 to 26 October
1985,
at Val Verde,
flea
samples
were
collected
from
dogs,
and
seven
were
collected
from
burrows.
tis. We
flagged
for
of
ground
flea and
5).
Midlake,
yielded
0.
0 of
species
taken
from
thirteen-lined
including
1 prairie
dog
caught
Deer
the bur15 pools
of eight
0. hir-
five
0.
33, NO. 4, OCTOBER
fleas
from
seven
of
including
of
VOL.
Vega
find
had
mouse
(Table
burrows
there
ground
squirrel
included
its
prairie
dog
flea
specialist,
fleas,
Meadow
voles
These
included
specialists,
the
asio;
aban-
dog
and
a deer
mouse
(Thomas,
1988).
collected
fleas
from
flea,
flea,
all
and
yielded
the ap-
Megabothris
prairie
no
deer
0.
Epitidia
four
rodent
species
in the valley,
and only found
Y pestis positive
fleas on prairie
dogs or in prairie dog
burrows.
It is important
to note
that three
species
fleas,
0. bacchi,
were
found
that were
R. sectilis
to be
lined
prairie
dog
A. wagneri
plague-infected
rie dog
burrows.
fleas were
collected
east
gust
one
not
and
Yersinia
in praipestis
at a gravel
positive
pit on the
side of Eagle
Nest
by NMEID
in Au1983:
one pool
of nine
0. bacchi
and
pool
of one 0. hirsuta
from
thirteenground
squirrel
burrows
and
one
pool of seven
0. labis,
and one pool of two
0. hirsuta
from
prairie
dog burrows.
Later, on 1 November
1983,
one
pool
containing
one
R.
sectilis,
hirsuta
and
one
pool
one
of eight
pool
of
0.
labis
48
0.
were
found
positive
at the same
area
(NMEID,
CDC,
unpublished
records).
Prairie
dog population
recovery
following plague
was variable.
Subsequent
to the
epizootic
at the north
end of the valley
in
CULLY
late
South
summer
the
vidual
vicinity
In
1985,
late summer
and late summer
Entrance,
AND
GUNNISON’S
1986 near
1987 in
of Val Verde,
there
were
indidogs
or small
aggregations.
prairie
spring
ET AL-PLAGUE
1986,
Vega
consisted
of
ha.
Because
ha
of
not
17 ani-
three
nearly
70 animals,
20 in August
1986.
but hunters
Approximately
We
rie
dogs
and
1987
entered
hibernation
October,
indicated
winter.
In
spread
over
and
that
April
emerged
the
ha
in June
counts
in
all survived
population
and
1987,
when
there
imately
200 animals.
had
good
over-winter
April
the
were
approxagain
when
June
(Cully,
in
began
the
July,
a steady
prairie
decline
at
numbers.
and
Fleas
pools
from
September
were
positive
pools
included
cynmnurzs,
and
itive
t.
September,
collected
were
10
on
8
on
1988,
for
0.
0.
hirsuta,
pools
bacchi
In
fewer
the middle
of the
valley
small
towns
recovering
At
Lake
the
September
there
were
still
at
prairie
over
following
dogs
a larger
25
time
area,
Eagle
located
at
This population
25 in September
that
0.
the
in spring
dogs
approximately
in
July
of six nullipano offspring.
determine
the
com-
there
were
apdogs,
both
adults
areas.
There
prairie
dog
of the
valley
source
of
is unknown.
at least
that
ley
appeared
again
we
of prairie
were
also other
colonies
at the
in July
1988.
three
plague
in the
It could
have
ways.
plague
is enzootic
in rodent
species
dogs,
Nest
on
of
in
but
goes
First,
it is possible
Moreno
Valthan
prairie
unnoticed.
recorded
Plague
there
and
was
by
been
or mammalian
from
other
areas
ground
At
1
the
reno
time
Valley,
underway
South
Piedras,
that
the
squirrels
were
been
25
es do
NM
epizootic
Moreno
1988,
predators
where
not
km
(J.
overlap
Third,
outside
species
Yersinia
in the
Taos
Jr.,
voles
the
their
plague
was
and
pers.
the source
thirteen-lined
because
Mo-
epizootic
near
F. Cully,
thirvoles
from praiValley.
epizootic
west
meadow
origin
that
plague
plague.
plague
was
Valley
and
the
of the
the
ranchers.
introduced
associated
with
squirrels,
meadow
another
40
by
in
Valley.
from
rodent
enzootic
fleas
pre-
1949
epizootic
described
may have
maintain
was
in
another
plague
Moreno
entered
in the
other
and deermice
were
all collected
rie dog burrows
in the Moreno
were
in
numbered
1987,
and
prairie
end
pestis-positive
teen-lined
spring
the
at those
isolated
that
and
there
than
consisted
is active
outside
the Moreno
plague
may
be introduced
the Moreno
Valley
by other
neg-
hirsuta
of
were
The
approximately
although
spread
end
dogs
10
0.
two
to
ac-
could
groups
year
before,
28 prairie
by raptors
carry
fleas
3).
1986.
Entrance
town.
approximately
was
of 25
south
prairie
two
labis,
The
the
mid-1960’s
Second,
none.
at Vega
0.
bacchi.
population
consisted
produced
unable
NMEID,
and
11 of 13 flea
Y. pestis.
The pos-
ative
3 0.
north.
consisted
(Table
there
were
burrows
the
1.5
an
of the two other
groups.
In July
where
the
six females
had
been
viously
1988,
there
were
143 prairie
2 ha grid;
on 10 August,
there
on 28 August,
there
were
four,
80;
were
The
Valley
On 4 July
dogs
on the
were
group
and
about
DISCUSSION
ha
19
dogs
in
on
715
colony,
separated
One
females
south
1997).
Beginning
Vega
1987.
rous
dogs
small
they
emerged
in Spring
1988,
the town’s
area had increased
in size to approximately
15 ha and
was
coalescing
with
another
small
colony
to the south.
When
the juveniles
emerged
in June
1988,
a visual
count
of prairie
dogs
on a marked
two
plot at Vega
found
180 prairie
dogs
on
trapped
and pups.
The two other
groups
to be of similar
size;
however,
were
unable
to get a clear
count
juveniles
These
animals
survival
and
DYNAMICS
Entrance
of
widely
present
proximately
had
only
South
estimate
position
1988,
in September
visual
nearly
1987,
8
about
prai-
POPULATION
be made
at that time.
At Val Verde
the population
that
occupied
approxthe juveniles
emerged
population
increased
to
50
DOG
we
the
curate
mals
in two groups
imately
2 ha. When
in June
1986,
the
killed
PRAIRIE
Tres
obs.).
If
of plague
in
ground
could
species
sites
not
have
rang-
outside
716
JOURNAL
the
OF WILDLIFE
Sangre
de
deermouse
that
does
Cristo
has
overlap
sible
source
been
implicated
DISEASES,
plague.
a
33, NO. 4, OCTOBER
Mountains.
a continuous
both
sites,
of
VOL.
Most
The
reservoir
for
plague
in NM
(Holdenried
and
Quan
1956)
and Colorado
(Barnes,
1982).
It took a minimum
of 3 yr for plague
to
progress
the
in
Gunnison’s
had
three
length
of the
prairie
dogs.
geographic
during
this
from
the
vegetative
study.
The
and
Each
Valley
epizootic
temporal
phase
as
of
temporary
isolated
the
barriers
epizootic.
At
to
the
middle
sections
of the valley
took
about
1 yr to extirpate
from
affected
colonies.
This
north
or,
1985).
about
County
At the
height
of the
ruptions
caused
We
speculate
dogs
by collapsing
that
it was
dispersing
towns
that
hospitable
prairie
Those
graphic
from
carried
habitat
and
cies as well. Oropsylla
were
the species
most
itive.
Oropsylla
labis
at
unmay
dis-
populations.
usually
prairie
dog
populations
to
same
barriers,
combined
isolation
of recovering
the
to
inthe
the
south.
with
geoprairie
dog
towns,
apparently
restricted
the backward
dispersal
of plague
into previously
affected
areas
so that
recovering
populations
were
not immediately
reinvaded
by plague
from
other
prairie
dog towns
to the south.
At all areas,
samples
rie dog fleas
on prairie
dog burrows.
species
at
probably
reflect
abundance
samples
while
the
seasonal
and
were
others
were
differences
activity
collected
because
in
collected
0.
erculata
spring.
These
volved
the
spring
late
on
found
that
dogs
or when
jumped
buronto
0.
to naive
labis,
the
dogs;
other
and
0.
predomiall three
rodent
spe-
and 0. labis
often
Y. pestis
posand
0. tuberculata
hirsuta
active
during
different
in summer
and 0. tubin the
species
cynomuris
flea
in prairie
dog
prairie
late
were
plague
dogs
et al.,
(Lechleitner
prairie
infected
on
were
labis
Gunnison’s
1968;
fall-early
also
in-
epizootics
in
in
South
Park
Fitzgerald,
1970,
1993)
and
Gunnison
County
(Rayor,
1985),
and among
white-tailed
prairie
dogs
(Cynomys
leucurus)
near
Meeteetse
(Wyoming,
USA;
Ubico
et al., 1988).
At South
Park
and Meeteetse
Oropsylla
idahoensLs,
a species
not found
in the Moreno
Valley,
was
important.
Oropsylla
hirsuta,
the
dominant
prairie
dog
flea species
in the
Moreno
Valley,
was present
in small
numbers
at South
Park,
and was not reported
at Meeteetse.
At the Gunnison
County
site
hirsuta
and 0. labis
were
important.
With
the high
rates
of mortality
recordamong
Moreno
in
in
seasons,
ed
flea
areas
found
were
hirsuta,
plague
among
prairie
dogs
(Barnes,
1993)
were
prairie
cynomuris
cynomuris
0.
non-praiin prairie
The differences
between
Vega
and
the other
two
flea
Vega
summer.
included
dogs
or
from
hirsuta,
species
epizootic
across
barriers
fleas
Oropsylla
0.
cynomuris
spread
of
if dispersing
camivores
the
plague-destroyed
plague
of the
infected
resulted
fleas,
contact
and
fleas
tuberculata
nant
fleas
to the rate
USA;
Ray-
Midlake,
in addition
to
residents,
marked
prairie
dogs were
caught
that
have
been
moving
as a result
of the
rculata
between
and
to
the epizootic
prairie
dogs
was similar
to
1 mo, similar
(Colorado,
dog
tube
new
hosts.
The
towns
may occur
or wide
ranging
within
probably
prairie
close
social
were
shared
towns.
the
progress
in South
Park,
(Colorado,
USA;
Lechleitner
et al., 1968;
Fitzgerald,
1970).
At Val Verde
the
initial
mortality
event
lasted
in Gunnison
infected
during
rows
transmission
here
0. labis and 0.
were
transferred
carry
phases
was
others
by natural
geographic
boundaries
that
appeared
function
spread
Moreno
plague
reported
from
have
species
of the
towns
distribution
and is a pos-
Deermice
1997
Gunnison’s
Valley
prairie
and
at
dogs
sites
in
in
the
Colorado
(Lechleitner
et al., 1962;
1968;
Fitzgerald,
1970;
Rayor,
1985;
Barnes,
1993).
Gunnison’s
prairie
dog
is an unlikely
maintenance
host species
for plague
between
epizootics.
There
are
simply
not
enough
imals
alive
after
an epizootic.
mammal
and flea species
are
Many
involved
sylvatic
Seventy-three
genera
dents
plague
and
have
world-wide.
more
been
than
found
species
naturally
200
another
with
of roinfected
CULLY
(Poland
and
(1978)
14
flea
0.
Weber
report
sectilis.
dent
species,
wild
carnivore
plicated
NM.
plification
be
as
in
Moreno
Valley.
populations
stable
as
bined
with
at two
sites
ment
of
dogs.
to
The
to the
points
thirteen-lined
were
found
along
than
in
stream
prairie
land
habitats
tween
the
valley,
dogs.
between
Verde
the
main
and
its
thirteen-lined
ground
inhibited
from
introduced
plague
middle
the
of
the
most
ground
cies
flea
and
also
often
found
on
dogs
and
squirrels
dog
burrows
and
at
fleas;
refuge
Midlake,
be-
mice
the
tant
opsylla
were
less
found
creek,
and
to
were
the
the
0.
positive
bacchi
from
a prairie
et al., 1964).
However,
no other
evidence
involved
with
an en-
plague
foci in
et al., 1964;
that
plague
at this time
meadow
in the
Mo-
Valley.
The presence
of Y. pestis
posR. sectilis
and A. wagneri
from prairie
burrows
provides
evidence
between
Near
Santa
were
found
to plague
to
and
a possible
(Holdenried
bacchi,
not
be
R.
dog
in prairie
and
dog
for plague
1956).
OrA. tvagneri
but
were
all
positive
in
of each
species
burrows,
and
Mo-
were
two
of plague.
col-
have
at
adults
Y.
prairie
flea species
for interspe-
Moreno
antibodies
Valley
tested
positive
(13%
at Vega,
40%
Entrance,
their
titers
and
100%
at Val Verwere
high.
At Vega
and South
reproduction
that
squiranother
the
spe-
transmission
at South
de),
and
from
the
Following
the
epizootics,
a large
proportion
of the surviving
Gunnison’s
prairie
dogs
in the
for Y. pestis
collected
consid-
cific
burrow
were
host
Quan,
fleas,
to be Y. pestis
Valley.
Positives
and
deer
resis-
were
sectilis
prairie
a route
mice
(NM)
moderately
therefore
enzootic
and
for
deer
Fe
ground
was
dog
collected
Califorare
spe-
ground
was
plague.
californicus)
hosts.
prairie
ground
1988
from
and
between
Thus,
each
position
predators,
lected
from
a thirteen-lined
rel burrow
and in September
1985
in
themselves.
in an excellent
thirteen-lined
pool
in
at
of
dogs
was
disappeared
shortly
before
the
epizootic
in prairie
dogs.
In August
a
found
voles
times
also
flea
thirteen-lined
meadow
cies
alternate
used
species,
populations
resulted
were
2,
interspecific
was
thirteen-lined
from
ered
there
epizothat
bacchi
was
rodent
(Microtus
of transmission
prairie
dogs.
of
north
frequently
for
dog
ap-
thirteen-lined
exchanged
squirrels
squirrels
plague
on
squirrels,
Prairie
ground
the
Oropsylla
abundant
most
1983,
from
valley.
itive
portion
Six-mile
the
zootic
host
for Y. pestis
at
California
(USA;
Goldenburg
squir-
outlier
squirrels
crossing
have
reno
of
peared
to slow
the progress
of the
otic among
prairie
dogs.
It is possible
for
mice,
also were
potential
hosts
for plague.
The
appar-
high
voles
Hudson
we have
wet-
thirds
deer
and
voles
Creek,
middle
colony
nia
frequent-
Six-mile
and
of plague.
two other
epizootics
could
grass-
drained
route
dogs
involve-
more
Poorly
along
north
and
Val
courses
spread
The
this
collection
(Tables
in prairie
of
mesic
supports
1988
squirrels.
deep
burrow
combined
with
frequent
bacchi
from
prairie
dogs
the
the
as un-
ground
the
positive
flea
may
at Midlake
dogs,
combacchi
fleas
ground
4),
dog
717
(0. bacin September
squirrel
meadow
at the
mortality
potential
thirteen-lined
in a prairie
1988,
of 0.
of a Y. pestis
ground
cycle
of
populations
in
be
discovery
DYNAMICS
ent population
Vega
with
low
ground
appeared
ground
squirrels
epizootic
in prairie
Y. pestis
positive
0.
Furthermore,
lands
cycle
Thirteen-lined
prairie
thirteen-lined
prior
to the
plague
chi)
POPULATION
am-
an
squirrels
the
The
DOG
thirteen-lined
voles
and
maintenance
with
NM,
serving
ground
involved
squirrel
the
Y.
species.
Thirteen-lined
ly
imto
species
in
dog
six
been
rodent
plague
prairie
and
antibodies
Multiple
did
or R.
20 ro-
have
or
maintain
Gunnison’s
rels
that
infection
PRAIRIE
Vega.
0.
but
species,
species
in
bacchi,
rabbit
two
probably
also
0.
GUNNISON’S
Weber
including
tuberculata
cynornuris,
(1978)
also identified
by
pestis
and
AND
In NM,
species,
A. tvagneri,
hirsuta,
not
1979).
Barnes,
listed
ET AL-PLAGUE
Entrance
there
may have
following
the
epizootic,
pestis
been
which
positive
among
had
individuals
a
smaller
established
been
so
might
number
the
popula-
of
718
JOURNAL
tion
OF WILDLIFE
a year
that
earlier.
tested
DISEASES,
Some
negative
of
at Vega
yearlings
epizootic
which
had
in spring
marked
yearlings
and
plague.
leitner
may
could
1970)
dogs
had
of 37
bodies
Such
sults
Y. pestis
zootics.
Valley
after
the
be
Gunnison’s
is similar
Valley
during
titers
in
from
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