Thamnophis
HumboldtHerps.com
| California Red-sided Garter Snake (T. s. infernalis) |
COLUBRIDS: Family - Colubridae
COLUBRIDS: Family - Colubridae
Information regarding species' and subspecies' nomenclature, general ranges, diet, reproduction,
and threats was cross-referenced using:
1. Pages 664-668, 669-670, 674-676, and plates 504, 511, 512, 530, and 545, The Audubon
Society Field Guide to North American Reptiles and Amphibians. c. 1979.
2. Pages 210-235, Reptiles of the Northwest. c. 2002.
3. Pages 373-387, Western Reptiles and Amphibians (3rd ed.). c. 2003.
Information regarding grass snake manure piles and the garter snake "pheromone mating trick" :
5. Pages 191-192, Encyclopedia of Reptiles and Amphibians (2nd ed.). c. 1998 / 2003.
Information regarding protection status of Common Garters:
Web6. (www.dfg.ca.gov/regulations/07-08-inland-fish-regs.pdf)
or page 18, California Freshwater Sport Fishing Regulations, 2007-2008.
and threats was cross-referenced using:
1. Pages 664-668, 669-670, 674-676, and plates 504, 511, 512, 530, and 545, The Audubon
Society Field Guide to North American Reptiles and Amphibians. c. 1979.
2. Pages 210-235, Reptiles of the Northwest. c. 2002.
3. Pages 373-387, Western Reptiles and Amphibians (3rd ed.). c. 2003.
Information regarding grass snake manure piles and the garter snake "pheromone mating trick" :
5. Pages 191-192, Encyclopedia of Reptiles and Amphibians (2nd ed.). c. 1998 / 2003.
Information regarding protection status of Common Garters:
Web6. (www.dfg.ca.gov/regulations/07-08-inland-fish-regs.pdf)
or page 18, California Freshwater Sport Fishing Regulations, 2007-2008.
Complete
Subfamily - Natricinae
Genus - Thamnophis
Genus - Thamnophis
Garter Snakes! These snakes are one of the most
common snakes found throughout North America. Often called "garden" snakes,
garter snakes belong to a large subfamily of serpents called natricines. Natricinae
includes snakes from both Asia and Europe and is one of the world's larger
subfamilies within the family Colubridae. In North America this group also contains
both ribbon snakes (also in the genus Thamnophis)) and a variety of water snakes.
Here in Northwestern California we have four species of garter snakes (underlined)
with a total of up to six subspecies. (White numbered names refer to all species or
subspecies within the area):
Common Garter Snake (Thamnophis sirtalis) - This species has up to 12
subspecies within its ranks throughout a good portion of the lower 48 states
(including extreme SE AK), Canada and Northern Mexico. In our area we may find;
[1] Caliornia Red-sided Garter Snake (T. s. infernalis)
[2] Valley Garter Snake (T. s. fitchi)
[3] Northwestern Garter Snake (Thamnophis ordinoides)- This species stands on
its own.
Pacific Coast Aquatic Garter Snake (Thamnophis atratus) - One of two subspecies
of this snake lives in our field of study;
[4] Oregon Garter Snake (T. a hydrophilus) - This subspecies hybridizes with the
Sierra Garter Snake (Thamnophis couchii) in Shasta (Pit River drainage). T.
atratus was once considered as a ssp. of the Sierra Garter Snake ( aka the Western
Aquatic Garter), however has recently joined the Santa Cruz Garter Snake
(Thamnophis atratus atratus) as a partner subspecies under the name of Pacific
Coast Aquatic Garter [T. atratus complex].
Western Terrestrial Garter Snake (Thamnophis elegans) - This species has 3
subspecies. In our range we may find:
[5] Coast garter Snake (T. e. terrestris)
[6] Mountain garter Snake (T. e. elegans)
[7] Wandering Garter Snake (T. e. vagrans) Note: Although this ssp. is not in
our range, its intergrade effects may be noticed in NC California.
Who's Who?
Identification of these species and subspecies is often quite a challenge due to the
fact that many of them have very similar features at first glance. In addition, hybrids
between individual species and intergrades between subspecies are common; this
often muddies up any standard attributes (unique colors, patterns, scale rows,
labial scale counts, internasal scale shape, head shape, etc.) ascribed to a certain
species or subspecies. It is important to note that recent studies reflect the
possibility that many species of garters may actually belong to only one "super"
species comprised of many races. Further research is pending.
If we are to base our comparisons on the current standards of species definition,
then understanding the common physical characteristics of each species and
subspecies is the first step in closing in on an ID. This, combined with the
cross-referencing of range maps in field guides (they don't all agree), as well as
knowing a species' preferred terrain, may add to an understanding of what species
or subspecies may be influencing the mixture of traits in hybrids or intergrades.
Please see Thamnophis (2) and (3) for ID comparisons.
General Information on Thamnophis
The genus Thamnophis may be found in every one of the mainland states of the
U.S. (except parts of Western Utah, Southern Nevada, Western Arizona, and SE
California), most of the southern provinces in Canada, throughout parts of Mexico,
and all the way south to Costa Rica. Most members of this genus are excellent
swimmers and, like both their New World and Old World cousins, are commonly
found near freshwater rivers, streams, lakes, brackish ponds and tidal marshes.
Therefore it is reasonable to ascertain why areas like the Mojave Desert and parts
of the Great Basin Desert are so inhospitable to these snakes. Desert species do
exist, but usually only when a regular supply of water is nearby.
Not surprisingly, garter snakes are generally known for their consumption of
amphibians and fish. Some species have even become immune to the skin toxins
of toads and newts. Many of the more terrestrial species will feed on lizards, small
snakes, small mammals, and birds and their eggs. Young garter snakes often
start their lives feeding on slugs, earthworms, and leeches.
All New World natricines bear live young (Most Old World species are egg-layers).
This is important among reptile species that live in colder climates as it allows the
mother to incubate her young "on the run." Cold climates don't offer consistently
warm incubation sites for eggs. This is one of the main reasons why some garters
have succeeded in establishing wide ranges throughout Canada.
As with most reptiles inhabiting cooler climates, many northern species of
Thamnophis hibernate. Garter snakes are often found hibernating in communal
dens often housing hundreds of individuals. These overwintering sites are often
shared with rattlesnakes (another cold weather-tolerant group of snakes).
Witnessing a "spring thaw" where the mouth of a cave belches hundreds of snakes
must be a sight to see!
Another such sight that has either fascinated or repelled human onlookers is that of
the mating practices among some species of Thamnophis. In many cases female
garters are much larger than males and are often outnumbered by them. Instances
have been photographed and documented where dozens of males have been
found competing for one large female. These "orgies" are often so competitive,
behavioral evolution has come up with a new trick. Occasionally a larger male
competing for the heat of the moment will emit pheromones that fool other
surrounding males into thinking he's the female. Often this distracts enough males
from the real target, and then, in the blink of a slink the imposter doubles back
towards the female for a better chance!
In regards to pheromones, all the members of this genus have a wonderful little
way of deterring predators. When under attack they will expel fecal matter
combined with a foul-smelling musk that comes from their anal glands. This nasty
habit is common among many natricines. Catch one! You'll see! Count on using
extra soap washing it off!
Garter snakes have a good reason for making such a big stink. Avid hunters though
they may be, garter snakes fall victim to variety of predators: Predatory shore birds
such as herons and egrets dine on them voraciously as do most raptors;
kingsnakes can take down adult garters, whereby some smaller species of
snake-eating snakes may feed on the juveniles; in the Eastern U.S. crocodilians
often take their share; larger frogs such as bullfrogs and even large fish take their
sweet revenge on these snakes when they are young; on land Thamnophis often
fall prey to raccoons, cats, foxes, skunks, and the like. While garters may not be at
the bottom of the food chain, they are certainly not near the top.
Of course man's influence, whether active or passive, has become the greatest
threat to these animals. Land development, pollution, irresponsible timber
harvesting, over-collecting, and the fear of snakes - all take their toll on populations.
The monitoring of garter snake populations is crucial, for these snakes are often
secondary indicators for determining water quality in streams, rivers, and lakes.
Fish, frogs and salamanders are primary indicators. Because they spend their
whole lives or part of their lives in water, pollutants like pesticide run-off directly
impact these animals. Resultant birth defects in amphibians is common due to the
permeability of their skin. Likewise, too much silt from landslides caused by
logging operations combined with current global warming trends often result in toxic
algae blooms that choke the water's oxygen supply. Here, entire aquatic
ecosystems just die off. Fish and amphibians are often at the top of a garter
snake's menu, so it is easy to imagine how fast one of these negative domino
effects can ripple throughout the food chain.
Throughout many areas of North America once common species are now teetering
on the brink of endangerment or extinction. One of the most beautiful snakes in the
United States is the San Francisco Garter Snake (a subspecies of the Common
Garter Snake). Land development as well as over-collecting has driven this snake's
numbers into the ground. It is now protected by law. In much of Southern California
it is prohibited to collect any Common Garter Snakes (Los Angeles, Orange,
Riverside, Ventura, and San Diego Counties).
common snakes found throughout North America. Often called "garden" snakes,
garter snakes belong to a large subfamily of serpents called natricines. Natricinae
includes snakes from both Asia and Europe and is one of the world's larger
subfamilies within the family Colubridae. In North America this group also contains
both ribbon snakes (also in the genus Thamnophis)) and a variety of water snakes.
Here in Northwestern California we have four species of garter snakes (underlined)
with a total of up to six subspecies. (White numbered names refer to all species or
subspecies within the area):
Common Garter Snake (Thamnophis sirtalis) - This species has up to 12
subspecies within its ranks throughout a good portion of the lower 48 states
(including extreme SE AK), Canada and Northern Mexico. In our area we may find;
[1] Caliornia Red-sided Garter Snake (T. s. infernalis)
[2] Valley Garter Snake (T. s. fitchi)
[3] Northwestern Garter Snake (Thamnophis ordinoides)- This species stands on
its own.
Pacific Coast Aquatic Garter Snake (Thamnophis atratus) - One of two subspecies
of this snake lives in our field of study;
[4] Oregon Garter Snake (T. a hydrophilus) - This subspecies hybridizes with the
Sierra Garter Snake (Thamnophis couchii) in Shasta (Pit River drainage). T.
atratus was once considered as a ssp. of the Sierra Garter Snake ( aka the Western
Aquatic Garter), however has recently joined the Santa Cruz Garter Snake
(Thamnophis atratus atratus) as a partner subspecies under the name of Pacific
Coast Aquatic Garter [T. atratus complex].
Western Terrestrial Garter Snake (Thamnophis elegans) - This species has 3
subspecies. In our range we may find:
[5] Coast garter Snake (T. e. terrestris)
[6] Mountain garter Snake (T. e. elegans)
[7] Wandering Garter Snake (T. e. vagrans) Note: Although this ssp. is not in
our range, its intergrade effects may be noticed in NC California.
Who's Who?
Identification of these species and subspecies is often quite a challenge due to the
fact that many of them have very similar features at first glance. In addition, hybrids
between individual species and intergrades between subspecies are common; this
often muddies up any standard attributes (unique colors, patterns, scale rows,
labial scale counts, internasal scale shape, head shape, etc.) ascribed to a certain
species or subspecies. It is important to note that recent studies reflect the
possibility that many species of garters may actually belong to only one "super"
species comprised of many races. Further research is pending.
If we are to base our comparisons on the current standards of species definition,
then understanding the common physical characteristics of each species and
subspecies is the first step in closing in on an ID. This, combined with the
cross-referencing of range maps in field guides (they don't all agree), as well as
knowing a species' preferred terrain, may add to an understanding of what species
or subspecies may be influencing the mixture of traits in hybrids or intergrades.
Please see Thamnophis (2) and (3) for ID comparisons.
General Information on Thamnophis
The genus Thamnophis may be found in every one of the mainland states of the
U.S. (except parts of Western Utah, Southern Nevada, Western Arizona, and SE
California), most of the southern provinces in Canada, throughout parts of Mexico,
and all the way south to Costa Rica. Most members of this genus are excellent
swimmers and, like both their New World and Old World cousins, are commonly
found near freshwater rivers, streams, lakes, brackish ponds and tidal marshes.
Therefore it is reasonable to ascertain why areas like the Mojave Desert and parts
of the Great Basin Desert are so inhospitable to these snakes. Desert species do
exist, but usually only when a regular supply of water is nearby.
Not surprisingly, garter snakes are generally known for their consumption of
amphibians and fish. Some species have even become immune to the skin toxins
of toads and newts. Many of the more terrestrial species will feed on lizards, small
snakes, small mammals, and birds and their eggs. Young garter snakes often
start their lives feeding on slugs, earthworms, and leeches.
All New World natricines bear live young (Most Old World species are egg-layers).
This is important among reptile species that live in colder climates as it allows the
mother to incubate her young "on the run." Cold climates don't offer consistently
warm incubation sites for eggs. This is one of the main reasons why some garters
have succeeded in establishing wide ranges throughout Canada.
As with most reptiles inhabiting cooler climates, many northern species of
Thamnophis hibernate. Garter snakes are often found hibernating in communal
dens often housing hundreds of individuals. These overwintering sites are often
shared with rattlesnakes (another cold weather-tolerant group of snakes).
Witnessing a "spring thaw" where the mouth of a cave belches hundreds of snakes
must be a sight to see!
Another such sight that has either fascinated or repelled human onlookers is that of
the mating practices among some species of Thamnophis. In many cases female
garters are much larger than males and are often outnumbered by them. Instances
have been photographed and documented where dozens of males have been
found competing for one large female. These "orgies" are often so competitive,
behavioral evolution has come up with a new trick. Occasionally a larger male
competing for the heat of the moment will emit pheromones that fool other
surrounding males into thinking he's the female. Often this distracts enough males
from the real target, and then, in the blink of a slink the imposter doubles back
towards the female for a better chance!
In regards to pheromones, all the members of this genus have a wonderful little
way of deterring predators. When under attack they will expel fecal matter
combined with a foul-smelling musk that comes from their anal glands. This nasty
habit is common among many natricines. Catch one! You'll see! Count on using
extra soap washing it off!
Garter snakes have a good reason for making such a big stink. Avid hunters though
they may be, garter snakes fall victim to variety of predators: Predatory shore birds
such as herons and egrets dine on them voraciously as do most raptors;
kingsnakes can take down adult garters, whereby some smaller species of
snake-eating snakes may feed on the juveniles; in the Eastern U.S. crocodilians
often take their share; larger frogs such as bullfrogs and even large fish take their
sweet revenge on these snakes when they are young; on land Thamnophis often
fall prey to raccoons, cats, foxes, skunks, and the like. While garters may not be at
the bottom of the food chain, they are certainly not near the top.
Of course man's influence, whether active or passive, has become the greatest
threat to these animals. Land development, pollution, irresponsible timber
harvesting, over-collecting, and the fear of snakes - all take their toll on populations.
The monitoring of garter snake populations is crucial, for these snakes are often
secondary indicators for determining water quality in streams, rivers, and lakes.
Fish, frogs and salamanders are primary indicators. Because they spend their
whole lives or part of their lives in water, pollutants like pesticide run-off directly
impact these animals. Resultant birth defects in amphibians is common due to the
permeability of their skin. Likewise, too much silt from landslides caused by
logging operations combined with current global warming trends often result in toxic
algae blooms that choke the water's oxygen supply. Here, entire aquatic
ecosystems just die off. Fish and amphibians are often at the top of a garter
snake's menu, so it is easy to imagine how fast one of these negative domino
effects can ripple throughout the food chain.
Throughout many areas of North America once common species are now teetering
on the brink of endangerment or extinction. One of the most beautiful snakes in the
United States is the San Francisco Garter Snake (a subspecies of the Common
Garter Snake). Land development as well as over-collecting has driven this snake's
numbers into the ground. It is now protected by law. In much of Southern California
it is prohibited to collect any Common Garter Snakes (Los Angeles, Orange,
Riverside, Ventura, and San Diego Counties).
Subfamily - Natricinae
Genus - Thamnophis
Genus - Thamnophis
| Thamnophis (2) I.D. Comparisons |
| Thamnophis (3) I.D. Comparisons |
| Thamnophis (4) Ranges, Terrain, etc... |
| California Red-sided Garter Snake (T. s. infernalis) |
| Northwestern Garter Snake (Thamnophis ordinoides) |
| Northwestern Garter Snake (Thamnophis ordinoides) |
| Oregon Garter Snake (T. a. hydrophilus) [striped variant] |
| Oregon Garter Snake (T. a. hydrophilus) [striped variant] |
Fun Fact about
an Old World
Egg-layer:
The Common Grass
Snakes of Europe, such as
those found in northern
Sweden, are capable of
maintaining healthy
populations in a subarctic
environment. The question
is, how can an egg-laying
reptile find a suitable
incubation site in such cool
conditions. Before humans
ever embraced agriculture,
it is thought that these
snakes existed in smaller
numbers due to the limited
amount of rocky southern
slopes (the only place to
incubate during cooler
summers). However, once
man started stacking
manure, grass snakes
quickly started capitalizing
on new terrain. In yet
another example of how
humans attract snake
populations closer to their
homes, these grass
snakes have prospered
because of the heat given
off by fermenting dung. The
huge manure heaps found
on larger farms often attract
grass snakes from miles
around. In many of these
northern parts it is not
uncommon to witness the
hatching of hundreds, even
thousands of baby grass
snakes out of a single large
pile.
an Old World
Egg-layer:
The Common Grass
Snakes of Europe, such as
those found in northern
Sweden, are capable of
maintaining healthy
populations in a subarctic
environment. The question
is, how can an egg-laying
reptile find a suitable
incubation site in such cool
conditions. Before humans
ever embraced agriculture,
it is thought that these
snakes existed in smaller
numbers due to the limited
amount of rocky southern
slopes (the only place to
incubate during cooler
summers). However, once
man started stacking
manure, grass snakes
quickly started capitalizing
on new terrain. In yet
another example of how
humans attract snake
populations closer to their
homes, these grass
snakes have prospered
because of the heat given
off by fermenting dung. The
huge manure heaps found
on larger farms often attract
grass snakes from miles
around. In many of these
northern parts it is not
uncommon to witness the
hatching of hundreds, even
thousands of baby grass
snakes out of a single large
pile.
| garter snake - (unknown sp.) Van Duzen River near Carlotta, CA |
| garter snake - (unknown sp.) Van Duzen River near Carlotta, CA |
| Coast Garter Snake (T. e. terrestris) |
| Coast Garter Snake (T. e. terrestris) |