Great Basin Naturalist Memoirs
Volume 2 Intermountain Biogeography: A Symposium
Article 4
3-1-1978
Zoogeography of reptiles and amphibians in the
Intermountain Region
Wilmer W. Tanner
Life Science Museum, Brigham Young University, Provo, Utah 84602
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Recommended Citation
Tanner, Wilmer W. (1978) "Zoogeography of reptiles and amphibians in the Intermountain Region," Great Basin Naturalist Memoirs:
Vol. 2, Article 4.
Available at: http://scholarsarchive.byu.edu/gbnm/vol2/iss1/4
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ZOOGEOGRAPHY OF REPTILES AND AMPHIBIANS
IN THE INTERMOUNTAIN REGION
Wilmer W. Tanner
1
if any, amphibians and reptiles are endemic to Utah. This is also true for much of the Great
upper Colorado Plateau, southern Idaho, and Wyoming. Many species that would seemingly survive in this
inland, mountainous area are not here. Only one widespread salamander and a few frogs and toads have occupied suitable habitats in the area. Lizards and snakes, like the amphibians, provide few distributions that extend
Abstract.— Few,
Basin,
throughout the area.
A
migration which presumably followed the Pleistocene Ice Age brought most of the species
into the area as climatic conditions
warmed.
species and subspecies indicate rather clearly that these vertebrates have invaded the Intermountain Region in relatively recent geological time. Only the periphery of Utah and adjoining
states to the east and west have been penetrated by many of the species in the regional fauna.
Distribution
Few,
if
now
tiles
maps
of our
modern
perhaps also true for
is
by forests of pinyon and juniper. We assume that climatic conditions then existed
which permitted considerable movement of
both reptiles and amphibians.
Ballinger and Tinkle (1972) and Larsen
and Tanner (1975) have assumed that there
were Pleistocene refugia in the southern
deserts of the United States and /or Mexico
which maintained the ancestral stock from
which many of the present species and subspecies of intermountain amphibian and
reptilian fauna have arisen. The disjunct
any, of the amphibians and rep-
present in Utah are endemic. This
all
intermountain
states except those in the south.
There
time
at
is
the
evidence that for a period of
close
of
the
Pleistocene
the
southern Great Basin deserts were more hu-
mid than
rat
at present. Studies of fossil pack
middens (Neotoma lepida) by Wells and
Jorgensen (1964), indicate that the low
Frenchman
were significantly
arid than at present. Middens now
less
found in areas where the dominant desert
shrubs are Larrea and Coleogyne have the
leaves, seed, and twigs of Juniperus osteosperma imbedded in the crystalline
urine." Wells and Jorgensen (1964) suggest
desert "ranges in the vicinity of
Flat
that
(Nevada Test
the present
Site)
populations
about 600 meters above
its
Nevada
position
leys into cooler, moister
desert valleys of southern
New
changed the valleys
is
deserts for
of
tions were,
Mexi-
and California must have been
considerably more moist and humid during
at least part of each year at about the same
geological time as the valley floors and low
foothills of southern Nevada were covered
Museum, Brigham Young
"is-
mountains as post-
many
into
species.
uninhabitable
The
xeric condi-
however, an invitation for other
species to move in, so that the lower Sonoran valleys and their associated mountain
co, Arizona,
'Life Science
the
Pleistocene drying slowly but continuously
about 10,000 years ago.
The
throughout
New
Mexico and Arizona are highly suggestive of widespread
populations being forced from the low val-
zonal position of the pi-
nyon-juniper forest in southern
scattered
land" mountains of
refugia
now
support a rich and varied series
of amphibians
If
we
and
reptiles.
accept the hypothesis that there
was a period of time between the cold, wet
Pleistocene and the dry hot conditions of
University, Provo, Utah 84602.
43
GREAT BASIN NATURALIST MEMOIRS
44
today
when much of
warm
the
southwestern
more humid and moist than at present, we can envision a time in which a great migration of
amphibians and reptiles moved toward the
plateaus and the mountainous areas of the
United States was
United
but
still
west
central
many
species of the south did not penetrate
to
environments
gion which
in
we might
States.
Nevertheless,
the Intermountain Re-
expect to be compatible
with their needs.
Many North American
seemingly
survive
today
species that
in
would
intermountain
environments are not here. In June 1942 I
had the privilege of escorting Dr. A. H.
No. 2
in southern
15,000
sumably, their isolated mountain distribution
and the rapidly drying conditions prevented
two plethodontid
them from reaching Colorado. To the west,
north, and south of Utah the deserts developed rapidly. Glacial lakes which were
Nevada about 10,000
to
years ago.
We
are aware of only
salamanders that have survived. The widespread tiger salamander may have been
If
it
here during the Pleistocene,
it
may
sent one of the
period
that
Once
few species able
remaining
by
the valleys
were
became
in
present
did exist
here during the Pleistocene.
ders
45
INTERMOUNTAIN BIOGEOGRAPHY: A SYMPOSIUM
1978
to
Fig. 2. Distribution of
arenicolor; (b)
southern portions of
their range. Pre-
some amphibians
Woodhouse's
toad,
western toad, Bufo microscaphus.
in
the southwestern United States:
Bufo woodhoasei;
valleys
salty
dis-
rem-
in small areas around waterways
and desert springs (Figs. 2c, 2d, and 9).
The drying out and warming of the
dry, the salaman-
expand
Basin
reduced to
amphibians
region.
isolated in the mountaintops with
no opportunity
many Great
nants; associated vegetation changes isolated
to survive
the
in
appeared or were
repre-
(c)
(a)
this
vast
Canyon
inland area
treefrog,
red-spotted toad, Bufo punctatus; and
(d)
Hyhi
south-
No. 2
GREAT BASIN NATURALIST MEMOIRS
46
provided an opportunity for species
in
the
southern deserts (northern Mexico and per-
haps some areas
Chihuahua, and
in Sonora,
Coahuila) to expand their ranges northward.
It is
now
possible to detect
some such range
expansions along valleys running north and
west from the international border.
all
Time does not permit an examination of
species, but we can examine one. The
leopard
lizard,
Crotaphytus
wislizeni,
ap-
pears to have emerged from a refugium in
the Chihuahua-Coahuila area and followed
routes approximately as indicated
rows
in
by the
ar-
Figure 3a. The migration resulted
Fig. 4. Present-day distribution of
tiles:
Fig.
3.
(a)
The theorized flow
distribution for the
leopard lizard Crotaphytus wislizeni;
distribution as
known
today.
(b)
geographical
(a)
tortoise,
southwestern rep-
desert iguana, Dipsosaurus dorsalis; (b) desert
Gopherus
agassizi, (c) zebratailed lizard, Calli-
saurus draconoides; and
variegatus.
(d)
banded gecko, Coleonyx
INTERMOUNTAIN BIOGEOGRAPHY: A SYMPOSIUM
1978
in the distributional
shown
in
pattern for the species
Figure 3b. In
this
and other speareas produced
of some
and geographical subspecies
have evolved in such areas as the Colorado
Plateau, Virgin River Valley, and the Great
Basin of Utah and Nevada. This is true not
only for the leopard lizards but for most of
the species that have extended their ranges
into the northern and western valleys.
Not all species moved as far or perhaps
cies
occupation
semi-isolation,
Fig. 5.
Distribution of southwest reptiles:
Urosaurus ornata;
(c)
(a)
as
fast.
47
An examination
of
present-day
ranges are the best indicators of the general
movements
of
that occurred.
23 species
(Figs.
2
The following list
4-8) all show
and
range extensions into the Great Basin and
the valleys of the Colorado drainage.
species
more
have either expanded
their
Some
range
rapidly or have been able to cross ele-
vation barriers of 5,000 feet or higher (Figs.
5 and 6) while others have not (Figs. 4 and
8).
Desert spiny lizard, Sreloporus magister;
side-blotched lizard, Uta stansburiana; and
(d)
less earless lizard,
(b)
tree lizard,
Holbrookia macu-
No. 2
GREAT BASIN NATURALIST MEMOIRS
48
Southwestern toad (Bufo microscaphus)
Woodhouse toad {Bufo woodhousei)
15.
3.
Red-spotted toad (Bufo punctatus)
16.
Western Blind Snake (Leptotyphhps humilis)
Western Patch-nosed Snake (Salvadora hexdepis)
Coachwhip Snake (Masticophis flagellum)
4.
Canyon
17.
Glossy Snake (Arizona elegans)
5.
Desert tortoise (Gopherus agassizi)
18.
Common
6.
Banded gecko (Coleonyx
variegatus)
19.
Black-necked Garter Snake (Thamnophis cyrtopsis)
1.
2.
14.
treefrog (Hyla arenicolor)
Kingsnake (Lampropeltis getulus)
7.
Desert iguana (Dipsosaurus dorsalis)
20.
Western Ground Snake (Sonora semianulata)
8.
Zebra-tailed lizard (Callisaurus draconoides)
21.
Mojave Rattlesnake (Crotalus scutulatus)
9.
Lesser Earless lizard (Holbrookia maculata)
22. Speckled Rattlesnake (Crotalus mitchelli)
23.
10.
Desert spiny lizard (Sceloporus magister)
11.
Side-blotched lizard (Uta stansburiana)
12.
Tree lizard (Urosaurus ornata)
13.
Western Whiptail (Cnemidophorus
Sidewinder (Crotalus cerastes)
Some
species
must
have
survived
Coachwhip
WESTERN STATES
Fig.
6.
Distribution of southwestern reptiles:
western blind snake, Leptotyphhps humilis;
tail,
Cnemidophorus
tigris.
the
Pleistocene in refugia that lay between the
tigris)
(c)
(a)
Western patchnosed snake, Salvadora hexalcpis;
coachwhip, Masticophis flagellum; and
(d)
(b)
western whip-
INTERMOUNTAIN BIOGEOGRAPHY: A SYMPOSIUM
1978
and
mountains
the
cold
climates
drier,
mild climates of southern plains. Such
of
the
49
northern or central Great Plains. Such species include:
species include:
2.
The Chorus Frog (Pseudacris tnseriata)
Smooth Green Snake (Opheodrys vernalis)
3.
Racer (Coluber
1.
1.
The Western Toad (Bufo
2.
Spotted Frog (Rana pretiosa)
3.
Rubber Boa (Charina bottae)
Western Garter Snake
4.
boreas)
These are eastern species which seem to
have entered through the northern Great
Plains (Fig. 10). Presumably, the smooth
(Thamnophis
Such species seemingly have moved north
as climatic
conditions permitted.
cupied only mountain valleys
They
into
the
species
have
Intermountain
oc-
in the south-
ern parts of their present range (Fig.
Other
apparently
Region
moved
the
Lampropeltis getulus.
(c)
much wider
distribution
in earlier times than at present. This
dicated by
If
9).
from
green snake had a
its
is
in-
disjunct distribution.
there are reptile species that survived
the Pleistocene in the lower valleys of the
Great Basin of Utah and Nevada, the short-
Arizona elegans;
(b)
black-necked garter
western ground snake, Sonora semianulata; and
(d)
common
Fig. 7. Distribution of southwestern reptiles: (a) Glossy snake
snake, Tluimnophis cyrtopsis;
constrictor)
kingsnake,
GREAT BASIN NATURALIST MEMOIRS
50
horned lizard (Phrynosoma dougkissi), the
western skink (Eumeces skiltonianus), Fig.
10a),
and the sagebrush
are
graciosus)
the
(Sceloporus
lizard
species
most
likely
to
now
range
from the valleys up to at least 9,000
the mountains and plateaus.
feet in
done
have
In
These
so.
species
reptiles
of
east
No. 2
originated
area
the
numbers of both amphibians and
came from
The Intermountain West
He
dan theory.
stated
the environment:
majority
the south or the south-
east.
present day intermountain amphibians and
great
or
the
far
reptiles
three alternatives
the
of
south
By
greater
of
stocks
the
to
question.
a good,
is
if
not
a classical, example of the David Starr Jor-
summary, we can conclude that the
ancestral
either
in
They can
1.
if
that
animals have
radical changes occur in
follow the environment and thus remain
constant.
They can remain and adapt
2.
to the
new
environ-
ment.
It
they can do neither, they will become extinct.
If
3.
may
not be possible to cite an example
of a reptile or amphibian that has remained
we do have some that have
wide distributions and little morphological
divergence. Two examples are the Charina
bottae and the Bufo boreas. Both have wide
constant. Yet
Mojave Rattlesnake
STERN STATES
distribution with
s \i*
f^.
little
external variation.
Without a fossil record, we do not know
how many amphibians and reptiles existed
in our area since late Pleistocene time and
were unsuccessful in the struggle for survival. Presumably, we have had during the
last
'V
ten thousand to fifteen thousand years
substantial
environmental changes that
\
_
fered challenges
LI
beyond the
ability of
of-
some
species to adapt. Other species have extend-
Sidewinder
WESTERN STATE!
ed their range through adaptive radiation,
which increased the number of geographical
subspecies
or
morphological clines
in
the
were occupied.
believe that the moveoccurring. The estab-
species as isolated habitats
There is reason to
ment north is still
Aj
lishment of populations of Crotalus mitchelli
Utah appear to be respecimen of C.
first
scutulatus was taken in 1954 and the first
C. mitchelli in 1960. Both were taken on
the southwest slope of the Beaver Dam
and
C. scutulatus in
cent
Speckled
\
N
Rattlesnake
WESTERI
(Fig.
8).
The
Mountains, only a few miles inside Utah.
Fig. 8. Distribution of southwestern reptiles: (a)
jave
rattlesnake,
Crotalus
Crotalus cerastes; and
mitchelli.
(e)
scutulatus;
(b)
Mo-
sidewinder,
speckled rattlesnake, Crotalus
then, these species have apparently
expanded their ranges and are seen more often by field workers.
Since
The northern plateau Lizard
(Sceloporus
INTERMOUNTAIN BIOGEOGRAPHY: A SYMPOSIUM
1978
u.
elongatus) has in recent times crossed the
central
areas
plateaus of Utah
through the low
between Emery and Salina and now
51
occurs along the foothills extending north to
Ephraim and south
have records of
to
Monroe.
this species
We
do not
west of the Se-
Western Toad
,'l
Fig. 9.
STATES
Amphibians and
Charina bottae;
(c)
more northern distribution but with populations extending south
West and the Great Basin: (a) Spotted frog, Rana pretiosa; (b) rubber boa,
reptiles with a
into parts of the Intermountain
western toad, Bufo boreas; and
(d)
common
garter snake, Ttiamnophis
sirtalis.
52
GREAT BASIN NATURALIST MEMOIRS
ELL
No. 2
INTEKMOL .STAIN BIOGEOGRAPHY!
1978
River.
vier
A specimen
long-nosed
the
of
M
A SYMI'OSH
53
LlTERAl HI. Cll ED
i
snake
(
Rhniocheilus
was recentl)
lecontet)
taken south of Dragerton- an indication that
this species
is
Ballinceb,
its
range.
Sauna
Ufa
conclusion,
In
many
areas in Utah
tensive)
have had
reduced by
mon
it
should
be
souk-
local,
their
human
reptile
that
others ex-
has
Etheridce
K
I
over-
on
some
Management, and
private,
Bureau
of
Land
state lands.
Stebbins
from
Stebbins
Figure
1966).
fa
is
for
10 years, the ranges of species used
this
study have changed
Fig.
10.
Amphibians and
in
35
eodrys
i.errui':
1
L966
and
the
J
genus
Mu*
Zool
Cenozou
glass
lizards
fOUtheni
Great
Plains.
186.
T'j
lizards
L975
Evolution
[guanidae
'
A held guide
to
Houghton
western repMifflin
Wells
B.
v.,
Pleistocene
changes
and C. D. Jobcensek
wood rat middens and
the Moja
in
)
which bav<
per woodlands. Science 143
i
re ord
1964
of juni-
1171-1173.
irthem distribution hut which seemingly have
Bla.
more comparable to those in Fig. 9 b smooth green
Cohtber "jnArutor: and d chorus frog. Pseudocrii mgfita.
this distribution
is
Co
limatic
<
little.
reptiles
Jreal
20
amphibians
entered the interrnouritain and Great Basin areas from the central Great
mec&s skiltonumu.%
IT
Publ
tin-
Boston
from
Etheridge fr961j. Even though the distribution maps have not been brought up to date
Late
from
of
83
I
scleroporine
C
R
tiles
i~
Misc
Tinkle
VV.
D.
and W. W. Tanneb
R
the-
Basin Nat
Figures lb, 3b, and 4-10 are taken largely
1
L961
Herpetologica
of
grazing
R
OphisaUTUi
populations
been
[guanidae]
Univ. Michigan
The most com-
activity.
influence
disruptive
noted
and
K.,
R.
Systematica and evolution
1072.
expanding
still
;
snake, ftyh-