Dependence of the Garter Snake Thamnophis elegans on Amphibians in the Sierra Nevada of California

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Society for the Study of Amphibians and Reptiles
Dependence of the Garter Snake Thamnophis elegans on Amphibians in the Sierra Nevada of
California
Author(s): W. Bryan Jennings, David F. Bradford, Dale F. Johnson
Source:
Journal of Herpetology,
Vol. 26, No. 4 (Dec., 1992), pp. 503-505
Published by: Society for the Study of Amphibians and Reptiles
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NOTES NOTES
thank J. Suffan for his valuable help during the field
work, and H. Nufiez and J. Frazier for helpful com-
ments on the manuscript.
LITERATURE
CITED
BENNETr,
A. F. 1980. The thermal dependence of
behavioral performance in small lizards. Anim.
Behav. 28:752-756.
DI CASTRI,
F., AND E. HAJEK. 1976. Bioclimatologia
de Chile. Imprenta Universidad Catolica de Chile,
Santiago. 129 pp.
HUEY,
R. B. 1974. Behavioral thermoregulation in
lizards: importance of associated cost. Science 184:
1001-1003.
, AND T. P. WEBSTER.
1976. Thermal biology
of Anolis lizards in a complex fauna: the cristatellus
group on Puerto Rico. Ecology 57:985-994.
LABRA,
A. 1992. Determinantes de variables fisiol6-
gicas y conductuales en dos especies de lagartos
Pristidactylus: filogenia y ambiente. Unpubl. M.S.
Thesis, Univ. de Chile, Santiago. 95 pp.
LAMBOROT, M., AND N. DIAZ. 1987. A new species
of Pristidactylus (Sauria: Iguanidae) from central
Chile and comments on the speciation in the ge-
nus. J. Herpetol. 21:29-37.
LEE,
J. 1974. The diel activity cycle of the lizard,
Xantusia henshawi. Copeia 1974:934-940.
MOORE-EDE, M., F. SULZMAN, AND C. FULLER. 1982.
The Clocks That Time Us. Harvard Univ. Press,
London. 448 pp.
PACKARD, G., AND T. BOARDMAN.
1988. The misuse
of ratios, indices, and percentages in ecophysio-
logical research. Physiol. Zool. 61:1-9.
SCHERER, E., AND S. HARRISON.
1988. Exogenous con-
trol of diel locomotor activity in the whitefish Co-
regonius clupeaformis:
effects of light and temper-
ature. Oecologia (Berlin) 76:254-260.
STEEL, R., AND J. TORRIE.
1985. Bioestadistica: Prin-
cipios y Procedimientos. McGraw-Hill Latinoam-
ericana, S.A., Bogota. 622 pp.
TANAKA, S. 1986. Thermal ecology of the forest-
dwelling agamid lizard, Japalura polygonata ishi-
gakiensis. J. Herpetol. 20:333-340.
TEMPLETON,
J. R. 1970. Reptiles. In G. C. Whittow
(ed.), Comparative Physiology of Thermoregula-
tion, Vol. 1., pp. 167-221. Academic Press, New
York.
Accepted: 28 July 1992.
Journal
of Herpetology, Vol. 26, No. 4, 503-505, 1992
Copyright 1992 Society for the Study of Amphibians and Reptiles
Dependence of the Garter Snake
Thamnophis elegans on Amphibians in
the Sierra Nevada of California
W. BRYAN JENNINGS, 4 DAVID F. BRADFORD,2 AND DALE
F. JOHNSON,3 'Department
of Biological
Sciences, Univer-
sity of California,
Santa Barbara,
California
93106, USA,
4
Present Address: Department of Biology, Box 19498,
University of Texas at Arlington, Arlington, Texas
76019, USA.
thank J. Suffan for his valuable help during the field
work, and H. Nufiez and J. Frazier for helpful com-
ments on the manuscript.
LITERATURE
CITED
BENNETr,
A. F. 1980. The thermal dependence of
behavioral performance in small lizards. Anim.
Behav. 28:752-756.
DI CASTRI,
F., AND E. HAJEK. 1976. Bioclimatologia
de Chile. Imprenta Universidad Catolica de Chile,
Santiago. 129 pp.
HUEY,
R. B. 1974. Behavioral thermoregulation in
lizards: importance of associated cost. Science 184:
1001-1003.
, AND T. P. WEBSTER.
1976. Thermal biology
of Anolis lizards in a complex fauna: the cristatellus
group on Puerto Rico. Ecology 57:985-994.
LABRA,
A. 1992. Determinantes de variables fisiol6-
gicas y conductuales en dos especies de lagartos
Pristidactylus: filogenia y ambiente. Unpubl. M.S.
Thesis, Univ. de Chile, Santiago. 95 pp.
LAMBOROT, M., AND N. DIAZ. 1987. A new species
of Pristidactylus (Sauria: Iguanidae) from central
Chile and comments on the speciation in the ge-
nus. J. Herpetol. 21:29-37.
LEE,
J. 1974. The diel activity cycle of the lizard,
Xantusia henshawi. Copeia 1974:934-940.
MOORE-EDE, M., F. SULZMAN, AND C. FULLER. 1982.
The Clocks That Time Us. Harvard Univ. Press,
London. 448 pp.
PACKARD, G., AND T. BOARDMAN.
1988. The misuse
of ratios, indices, and percentages in ecophysio-
logical research. Physiol. Zool. 61:1-9.
SCHERER, E., AND S. HARRISON.
1988. Exogenous con-
trol of diel locomotor activity in the whitefish Co-
regonius clupeaformis:
effects of light and temper-
ature. Oecologia (Berlin) 76:254-260.
STEEL, R., AND J. TORRIE.
1985. Bioestadistica: Prin-
cipios y Procedimientos. McGraw-Hill Latinoam-
ericana, S.A., Bogota. 622 pp.
TANAKA, S. 1986. Thermal ecology of the forest-
dwelling agamid lizard, Japalura polygonata ishi-
gakiensis. J. Herpetol. 20:333-340.
TEMPLETON,
J. R. 1970. Reptiles. In G. C. Whittow
(ed.), Comparative Physiology of Thermoregula-
tion, Vol. 1., pp. 167-221. Academic Press, New
York.
Accepted: 28 July 1992.
Journal
of Herpetology, Vol. 26, No. 4, 503-505, 1992
Copyright 1992 Society for the Study of Amphibians and Reptiles
Dependence of the Garter Snake
Thamnophis elegans on Amphibians in
the Sierra Nevada of California
W. BRYAN JENNINGS, 4 DAVID F. BRADFORD,2 AND DALE
F. JOHNSON,3 'Department
of Biological
Sciences, Univer-
sity of California,
Santa Barbara,
California
93106, USA,
4
Present Address: Department of Biology, Box 19498,
University of Texas at Arlington, Arlington, Texas
76019, USA.
2Environmental
Science and Engineering
Program,
School
of Public Health, University of California, Los Angeles,
California 90024, USA, and 3P.O. Box 461, Lee Vining,
California
93541, USA.
Thamnophis
elegans (western terrestrial garter snake)
is the only garter snake inhabiting the Sierra Nevada
above approximately 2400 m elevation (Stebbins, 1985),
ranging up to at least 3400 m elevation (pers. obs.).
In this region its geographic range largely overlaps
that of five species of aquatic-breeding amphibians:
Ambystoma
macrodactylum
(long-toed salamander); Bufo
boreas
(western toad); B. canorus
(Yosemite toad); Pseu-
dacris [=Hyla] regilla (Pacific treefrog); and Rana mus-
cosa (mountain yellow-legged frog) (Stebbins, 1985).
Together, these amphibians breed in a variety of hab-
itats, including both permanent and ephemeral wa-
ters such as lakes, ponds, shallow meadow pools, and
stream pools. Thamnophis
e. elegans, the subspecies in-
habiting the Sierra Nevada, is known to depend
heavily on at least some of these species as prey: Bufo
spp. (Fitch, 1941; Cunningham, 1955; Arnold and
Wassersug, 1978); P. regilla
(Fitch, 1941; Cunningham,
1955; White and Kolb, 1974; Arnold and Wassersug,
1978); and R. muscosa
(pers. obs.). In the present study
we document the distribution of T. elegans in the high
Sierra relative to the distribution of these amphibians,
and test the hypothesis that T. elegans is dependent
on amphibians to such an extent that the presence of
amphibians at a site is a prerequisite for its existence.
An implication of such a dependence would be that
as local amphibian populations become extinct in the
Sierra Nevada, which has been observed in recent
decades (Wake, 1991; Bradford et al., unpubl. obs.), T.
elegans may also disappear.
We surveyed for T. elegans as part of a study of
amphibian distribution and associated water chem-
istry above 2440 m elevation in the Sierra Nevada.
We included T. elegans in the study during 1991 when
a randomly-selected subset of 15 of the 30 total survey
areas was searched. The center of each survey area
was randomly selected from a uniform grid estab-
lished by the U.S. Environmental Protection Agency's
Environmental Monitoring and Assessment Program.
Each survey area consisted of a 15 km2 circle (i.e., 4.4
km diameter) with the selected point in the center,
exclusive of any portion of the circle that was below
2440 m elevation. Two individuals (Jennings and
Johnson) searched each survey area in a manner de-
signed to provide data for sites that contain each am-
phibian species and sites that do not, and to ascertain
whether a breeding population of each species exists
in the survey area. Survey areas were searched during
daytime in early and midsummer (12 June to 2 Au-
gust) when amphibian larvae are present and most
visible and abundant in shallow water near shore
(Bradford, 1984). The survey areas were searched in
a non-random manner until five "different or sepa-
rate" sites containing larvae of each amphibian spe-
cies were found, or until enough of the survey area
had been searched to be confident that a breeding
population of a species did not exist in the survey
area. "Different or separate" sites were defined as
ones separated by more than 200 m or ones that ap-
peared to differ in water characteristics or sources
(e.g., a pool in a stream versus an isolated pond). Sites
were surveyed for amphibian larvae and T. elegans by
2Environmental
Science and Engineering
Program,
School
of Public Health, University of California, Los Angeles,
California 90024, USA, and 3P.O. Box 461, Lee Vining,
California
93541, USA.
Thamnophis
elegans (western terrestrial garter snake)
is the only garter snake inhabiting the Sierra Nevada
above approximately 2400 m elevation (Stebbins, 1985),
ranging up to at least 3400 m elevation (pers. obs.).
In this region its geographic range largely overlaps
that of five species of aquatic-breeding amphibians:
Ambystoma
macrodactylum
(long-toed salamander); Bufo
boreas
(western toad); B. canorus
(Yosemite toad); Pseu-
dacris [=Hyla] regilla (Pacific treefrog); and Rana mus-
cosa (mountain yellow-legged frog) (Stebbins, 1985).
Together, these amphibians breed in a variety of hab-
itats, including both permanent and ephemeral wa-
ters such as lakes, ponds, shallow meadow pools, and
stream pools. Thamnophis
e. elegans, the subspecies in-
habiting the Sierra Nevada, is known to depend
heavily on at least some of these species as prey: Bufo
spp. (Fitch, 1941; Cunningham, 1955; Arnold and
Wassersug, 1978); P. regilla
(Fitch, 1941; Cunningham,
1955; White and Kolb, 1974; Arnold and Wassersug,
1978); and R. muscosa
(pers. obs.). In the present study
we document the distribution of T. elegans in the high
Sierra relative to the distribution of these amphibians,
and test the hypothesis that T. elegans is dependent
on amphibians to such an extent that the presence of
amphibians at a site is a prerequisite for its existence.
An implication of such a dependence would be that
as local amphibian populations become extinct in the
Sierra Nevada, which has been observed in recent
decades (Wake, 1991; Bradford et al., unpubl. obs.), T.
elegans may also disappear.
We surveyed for T. elegans as part of a study of
amphibian distribution and associated water chem-
istry above 2440 m elevation in the Sierra Nevada.
We included T. elegans in the study during 1991 when
a randomly-selected subset of 15 of the 30 total survey
areas was searched. The center of each survey area
was randomly selected from a uniform grid estab-
lished by the U.S. Environmental Protection Agency's
Environmental Monitoring and Assessment Program.
Each survey area consisted of a 15 km2 circle (i.e., 4.4
km diameter) with the selected point in the center,
exclusive of any portion of the circle that was below
2440 m elevation. Two individuals (Jennings and
Johnson) searched each survey area in a manner de-
signed to provide data for sites that contain each am-
phibian species and sites that do not, and to ascertain
whether a breeding population of each species exists
in the survey area. Survey areas were searched during
daytime in early and midsummer (12 June to 2 Au-
gust) when amphibian larvae are present and most
visible and abundant in shallow water near shore
(Bradford, 1984). The survey areas were searched in
a non-random manner until five "different or sepa-
rate" sites containing larvae of each amphibian spe-
cies were found, or until enough of the survey area
had been searched to be confident that a breeding
population of a species did not exist in the survey
area. "Different or separate" sites were defined as
ones separated by more than 200 m or ones that ap-
peared to differ in water characteristics or sources
(e.g., a pool in a stream versus an isolated pond). Sites
were surveyed for amphibian larvae and T. elegans by
503 503

NOTES
TABLE 1. Presence/absence of amphibians at 12
sites where Thamnophis
elegans was found. Ambystoma
macrodactylum
is omitted because it was not found in
any survey area. "+" = present; "-" = absent.
Presence/absence
of amphibians
Number
Survey Site of T. Any P. Bufo R.
area no. elegans Species regilla spp. muscosa
A 1 1 + + - -
B 2 3 + + +
C 3 3 + + - -
D 4 1 + + - -
5 1 + + - -
E 6 4 + + - -
7 3 + + -
F 8 1 + - + -
9 1 + + -
G 10 1 + + +
11 1 + + -
12 2 + + - -
Totals for T. elegans sites:
7 12 22 12 11 3 0
Totals for all sites:
15 115 22 73 59 10 15
walking near or in shallow water near shore. Also
surveyed were up to five "different or separate" sites
that appeared to represent potential breeding habitat
for each amphibian species, but which lacked the spe-
cies.
Individual T. elegans were usually captured, ex-
amined, and released. They were defined as "small"
if they appeared shorter than approximately 18 cm
snout-vent length, and as "large" if longer than this.
"Small" individuals were presumably young of the
year (White and Kolb, 1974).
Twenty-two T.
elegans
(10 small/ 12 large) were found
in 7 of the 15 survey areas and 12 of the 115 individual
sites (Table 1). Neither T. elegans
nor amphibians were
found in 3 of the 15 survey areas. Thamnophis
elegans
occurred only in sites where amphibians were present
(Table 1). The probability that T. elegans
would occur
by chance only at sites where amphibians were pres-
ent was extremely low (P = 0.0045; Table 2).
Thamnophis elegans was found primarily in associ-
ation with P. regilla
(Table 1). It occurred with P. regilla
alone (N = 9 sites), P. regilla and Bufo spp. together
(N = 2), and Bufo spp. alone (N = 1), but at no sites
with R. muscosa. These differences appear to be due
largely to the differences in relative abundance of the
three amphibian genera, because P. regilla
was by far
the most frequently represented amphibian in the
survey (Table 1). Comparisons of presence/absence
of T. elegans
versus each amphibian species showed a
significant relationship only for P. regilla (X2
= 7.03,
df 1, P < 0.01 for P. regilla;
Fisher exact test, P > 0.10
for Bufo spp. and R. muscosa).
The habitats in which T. elegans was found gener-
ally were in the lodgepole pine (Pinus
murrayana)
zone,
in or adjacent to permanent ponds with emergent
vegetation or shallow ephemeral meadow ponds. El-
TABLE 2. Probability (P) that all sites containing
T. elegans also contain amphibians. P is computed as
the product of the frequency of sites with amphibians
within each survey area (F) for all 12 sites with T.
elegans, i.e., P = F, F2 .. . F12,
where subscripts rep-
resent the 12 sites. F is computed as the fraction: num-
ber of sites with amphibians/total sites searched.
No. sites Frequency
of
with T. sites with
Survey
area Total sites elegans amphibians
(F)
A 16 1 0.625
B 13 1 0.615
C 11 1 0.364
D 4 2 1.000
E 7 2 0.429
F 12 2 0.500
G 9 3 0.889
Totals 72 12
P = 0.0045.
evation ranged from 2510 to 3260 m. Individuals were
found swimming in ponds (18 of 22), along the shore-
line of ponds (3), or within 1 m of a small creek (1).
Thamnophis
elegans
was never found in or near stand-
ing or running water containing fish rather than am-
phibians.
This study shows that the occurrence of T. elegans
in the Sierra Nevada at high elevation is strongly
associated with the presence of amphibians. Indeed,
it is possible that the presence of amphibians is a
prerequisite for the existence of T. elegans in this re-
gion. Thamnophis
elegans here may depend on am-
phibians as its primary food source. Thamnophis
e. ele-
gans elsewhere preys primarily on amphibians,
especially recently metamorphosed P. regilla and B.
boreas,
although it often takes a variety of other prey
including fish, leeches, mammals, lizards, and slugs
(Fitch, 1941;
Cunningham, 1955;
White and Kolb, 1974;
Arnold and Wassersug, 1978). Indeed, T. e. elegans in
some areas appears to prefer amphibian prey, but
switches to alternative prey such as fish and leeches
in years when amphibians are not available (Arnold
and Wassersug, 1978).
Interestingly, T. e. elegans
in the high Sierra appears
to be strictly an aquatic garter snake, whereas else-
where in its range its inhabits primarily terrestrial
habitats (Fitch, 1940; Cunningham, 1955; Stebbins,
1985). In this study we found 18 of the 22 snakes
swimming in water, and no individuals more than a
meter from standing water, despite travelling many
kilometers through terrestrial habitats within each
survey area. Indeed, the vast majority of the time
spent and area traversed in the study areas was in
terrestrial habitats. This apparently anomalous asso-
ciation with the aquatic environment has been ob-
served in northeastern California, where T. e. elegans
occurs in aquatic habitats in a generally arid region
(Fitch, 1940). Fitch argued that T. e. elegans
is primarily
aquatic in northeastern California because humid ter-
restrial habitats are scarce and other species of Tham-
nophis, which are typically aquatic, are absent. Such
may also be the case with T. e. elegans in the Sierra
504

NOTES NOTES
Nevada at high elevation. Terrestrial habitats beyond
the typically narrow riparian zone are quite arid in
comparison to many terrestrial habitats at lower el-
evation and farther north within the range of T. e.
elegans. Moreover, neither T. couchi nor T. sirtalis ex-
tend above approximately 2400 m elevation in the
Sierra Nevada (Stebbins, 1985; pers. obs.).
In this study T. elegans was not found at sites con-
taining R. muscosa,
although this apparent lack of as-
sociation was not statistically significant. It is unlikely
that T. elegans avoids R. muscosa because one of us
(Bradford) has observed T. elegans at other sites con-
taining only R. muscosa,
and has verified consumption
of both adults and tadpoles of this species by inducing
regurgitation of snakes. Moreover, Thamnophis
are of-
ten major predators of other ranid frogs (e.g., Licht,
1974).
During the past several decades, B. canorus and R.
muscosa
have disappeared from many localities at high
elevation in the Sierra Nevada (Phillips, 1990; Brad-
ford et al., 1992; D. L. Martin, pers. comm.; Sherman
and Morton, pers. comm.). Estimates of the magnitude
of these apparent extinctions are about 50% or more
of populations extant in 1950 for both species (Brad-
ford et al., unpubl. obs.; D. L. Martin, unpubl. obs.).
In contrast, P. regilla continues to remain an abundant
and widespread amphibian in the high Sierra, and it
shows no evidence of recent population declines
(Bradford et al., unpubl. obs.). Reasons for the de-
clines of B. canorus and R. muscosa
are not clear (Brad-
ford et al., 1992), but may be related to the recent
population declines of many amphibians around the
world (Wake, 1991). An implication from the present
study is that T. elegans should not be dramatically
affected by declines of B. canorus and R. muscosa,
be-
cause T. elegans
appears to be more strongly associated
with P. regilla than these species, and P. regilla is far
more widespread (Table 1). However, if populations
of P. regilla become extinct like many populations of
B. canorus
and R. muscosa,
sympatric populations of T.
elegans may also suffer the same fate.
Acknowledgments.-This study was conducted un-
der Contract No. A932-139 from the California Air
Resources Board to D. F. Bradford and M. S. Gordon.
LITERATURE
CITED
ARNOLD,
S. J., AND R. J. WASSERSUG.
1978. Differ-
ential predation on metamorphic anurans by gar-
ter snakes (Thamnophis):
social behavior as a pos-
sible defense. Ecology 59:1014-1022.
BRADFORD,
D. F. 1984. Temperature modulation in
a high-elevation amphibian, Rana muscosa.
Copeia
1984:966-976.
1989. Allotopic distribution of native frogs
and introduced fishes in high Sierra Nevada lakes
of California: implication of the negative effect of
fish introductions. Copeia 1989:775-778.
, C. SWANSON,
AND M. S. GORDON. 1992. Ef-
fects of low pH and aluminum on two declining
species of amphibians in the Sierra Nevada, Cal-
ifornia. J. Herpetol. 26:369-377.
CUNNINGHAM, J. D. 1955. Notes on the ecology of
Thamnophis
e. elegans (Baird and Girard). Herpe-
tologica 11:152.
FITCH,
H. S. 1940. A biogeographical study of the
Nevada at high elevation. Terrestrial habitats beyond
the typically narrow riparian zone are quite arid in
comparison to many terrestrial habitats at lower el-
evation and farther north within the range of T. e.
elegans. Moreover, neither T. couchi nor T. sirtalis ex-
tend above approximately 2400 m elevation in the
Sierra Nevada (Stebbins, 1985; pers. obs.).
In this study T. elegans was not found at sites con-
taining R. muscosa,
although this apparent lack of as-
sociation was not statistically significant. It is unlikely
that T. elegans avoids R. muscosa because one of us
(Bradford) has observed T. elegans at other sites con-
taining only R. muscosa,
and has verified consumption
of both adults and tadpoles of this species by inducing
regurgitation of snakes. Moreover, Thamnophis
are of-
ten major predators of other ranid frogs (e.g., Licht,
1974).
During the past several decades, B. canorus and R.
muscosa
have disappeared from many localities at high
elevation in the Sierra Nevada (Phillips, 1990; Brad-
ford et al., 1992; D. L. Martin, pers. comm.; Sherman
and Morton, pers. comm.). Estimates of the magnitude
of these apparent extinctions are about 50% or more
of populations extant in 1950 for both species (Brad-
ford et al., unpubl. obs.; D. L. Martin, unpubl. obs.).
In contrast, P. regilla continues to remain an abundant
and widespread amphibian in the high Sierra, and it
shows no evidence of recent population declines
(Bradford et al., unpubl. obs.). Reasons for the de-
clines of B. canorus and R. muscosa
are not clear (Brad-
ford et al., 1992), but may be related to the recent
population declines of many amphibians around the
world (Wake, 1991). An implication from the present
study is that T. elegans should not be dramatically
affected by declines of B. canorus and R. muscosa,
be-
cause T. elegans
appears to be more strongly associated
with P. regilla than these species, and P. regilla is far
more widespread (Table 1). However, if populations
of P. regilla become extinct like many populations of
B. canorus
and R. muscosa,
sympatric populations of T.
elegans may also suffer the same fate.
Acknowledgments.-This study was conducted un-
der Contract No. A932-139 from the California Air
Resources Board to D. F. Bradford and M. S. Gordon.
LITERATURE
CITED
ARNOLD,
S. J., AND R. J. WASSERSUG.
1978. Differ-
ential predation on metamorphic anurans by gar-
ter snakes (Thamnophis):
social behavior as a pos-
sible defense. Ecology 59:1014-1022.
BRADFORD,
D. F. 1984. Temperature modulation in
a high-elevation amphibian, Rana muscosa.
Copeia
1984:966-976.
1989. Allotopic distribution of native frogs
and introduced fishes in high Sierra Nevada lakes
of California: implication of the negative effect of
fish introductions. Copeia 1989:775-778.
, C. SWANSON,
AND M. S. GORDON. 1992. Ef-
fects of low pH and aluminum on two declining
species of amphibians in the Sierra Nevada, Cal-
ifornia. J. Herpetol. 26:369-377.
CUNNINGHAM, J. D. 1955. Notes on the ecology of
Thamnophis
e. elegans (Baird and Girard). Herpe-
tologica 11:152.
FITCH,
H. S. 1940. A biogeographical study of the
ordinoides
artenkreis of garter snakes (genus Tham-
nophis). Univ. California Publ. Zool. 44:1-150.
1941. The feeding habits of California garter
snakes. California Fish Game 27:2-32.
LICHT,
L. E. 1974. Survival of embryos, tadpoles, and
adults of the frogs Rana aurora aurora and Rana
pretiosa
sympatric in southwestern British Colum-
bia. Can. J. Zool. 52:613-627.
PHILLIPS,
K. 1990. Where have all the frogs and toads
gone? BioScience 40:422-424.
STEBBINS,
R. C. 1985. A Field Guide to Western Rep-
tiles and Amphibians. Houghton Mifflin, Boston.
336 p.
WAKE,
D. B. 1991. Declining amphibian populations.
Science 253:860.
WHITE,
M., AND
J. A. KOLB. 1974. A preliminary study
of Thamnophis
near Sagehen Creek, California. Co-
peia 1974:126-136.
Accepted: 28 July 1992.
Journal
of Herpetology, Vol. 26, No. 4, 505-508, 1992
Copyright 1992 Society for the Study of Amphibians and Reptiles
Northernmost Record of
Desmognathus ochrophaeus:
Biochemical Identification in
the Chateauguay River
Drainage Basin, Quebec
TIMOTHY F. SHARBEL1 AND JOEL BONIN,2 'Redpath Mu-
seum, McGill University, 859 Sherbrooke
West, Montreal,
Quebec
H3A 2K6, Canada,
and 2St. Lawrence
Valley Nat-
ural History Society, 21111 Bord du Lac, Ste-Anne-de-
Bellevue, Quebec
H9X 1CO,
Canada.
The two most common species of the salamander
genus Desmognathus,
D. fuscus and D. ochrophaeus,
are
widespread in Eastern North America (Conant and
Collins, 1991). Their similar external morphologies,
overlapping ranges, high degrees of intraspecific
variation, and propensity for hybridization have pre-
sented difficulties for field identification in regions
of sympatry (Karlin and Guttman, 1986; Conant and
Collins, 1991). Isozyme electrophoresis has therefore
become a useful tool for the identification of individ-
uals, especially within hybrid zones (Tilley et al., 1978;
Karlin and Guttman, 1981; Tilley and Schwerdtfeger,
1981; Karlin et al., 1984; Karlin and Guttman, 1986;
Tilley, 1988). To date, D. fuscus is the only member of
the genus documented in the Chateauguay River
drainage basin in southern Quebec (Conant and Col-
lins, 1991). In this paper we present biochemical data
documenting the northernmost record of D. ochro-
phaeus,
and the first record for this species in the basin.
During a survey of a brook (310 m elevation) on
Covey Hill, Quebec, at the northernmost edge of the
Adirondack Mountains (45001'18"N, 73?49'13"E;
340
m elevation), we discovered Desmognathus
with vari-
able dorsal coloration. The brook is part of the Cha-
teauguay River drainage basin (Ministere des Terres
et Forets du Quebec, 1971), which drains northward
into the St. Lawrence River. The brook is spring fed
ordinoides
artenkreis of garter snakes (genus Tham-
nophis). Univ. California Publ. Zool. 44:1-150.
1941. The feeding habits of California garter
snakes. California Fish Game 27:2-32.
LICHT,
L. E. 1974. Survival of embryos, tadpoles, and
adults of the frogs Rana aurora aurora and Rana
pretiosa
sympatric in southwestern British Colum-
bia. Can. J. Zool. 52:613-627.
PHILLIPS,
K. 1990. Where have all the frogs and toads
gone? BioScience 40:422-424.
STEBBINS,
R. C. 1985. A Field Guide to Western Rep-
tiles and Amphibians. Houghton Mifflin, Boston.
336 p.
WAKE,
D. B. 1991. Declining amphibian populations.
Science 253:860.
WHITE,
M., AND
J. A. KOLB. 1974. A preliminary study
of Thamnophis
near Sagehen Creek, California. Co-
peia 1974:126-136.
Accepted: 28 July 1992.
Journal
of Herpetology, Vol. 26, No. 4, 505-508, 1992
Copyright 1992 Society for the Study of Amphibians and Reptiles
Northernmost Record of
Desmognathus ochrophaeus:
Biochemical Identification in
the Chateauguay River
Drainage Basin, Quebec
TIMOTHY F. SHARBEL1 AND JOEL BONIN,2 'Redpath Mu-
seum, McGill University, 859 Sherbrooke
West, Montreal,
Quebec
H3A 2K6, Canada,
and 2St. Lawrence
Valley Nat-
ural History Society, 21111 Bord du Lac, Ste-Anne-de-
Bellevue, Quebec
H9X 1CO,
Canada.
The two most common species of the salamander
genus Desmognathus,
D. fuscus and D. ochrophaeus,
are
widespread in Eastern North America (Conant and
Collins, 1991). Their similar external morphologies,
overlapping ranges, high degrees of intraspecific
variation, and propensity for hybridization have pre-
sented difficulties for field identification in regions
of sympatry (Karlin and Guttman, 1986; Conant and
Collins, 1991). Isozyme electrophoresis has therefore
become a useful tool for the identification of individ-
uals, especially within hybrid zones (Tilley et al., 1978;
Karlin and Guttman, 1981; Tilley and Schwerdtfeger,
1981; Karlin et al., 1984; Karlin and Guttman, 1986;
Tilley, 1988). To date, D. fuscus is the only member of
the genus documented in the Chateauguay River
drainage basin in southern Quebec (Conant and Col-
lins, 1991). In this paper we present biochemical data
documenting the northernmost record of D. ochro-
phaeus,
and the first record for this species in the basin.
During a survey of a brook (310 m elevation) on
Covey Hill, Quebec, at the northernmost edge of the
Adirondack Mountains (45001'18"N, 73?49'13"E;
340
m elevation), we discovered Desmognathus
with vari-
able dorsal coloration. The brook is part of the Cha-
teauguay River drainage basin (Ministere des Terres
et Forets du Quebec, 1971), which drains northward
into the St. Lawrence River. The brook is spring fed
505 505