Northwestern Alligator Lizard
| Northwestern Shasta - intergrade |
ANGUIDS: Family - Anguidae
HumboldtHerps.com
ANGUIDS: Family - Anguidae
Northwestern California offers two species of anguid lizards: the Northern Alligator
Lizard and the Southern Alligator Lizard. Alligator lizards have elongated stiff bodies.
This is because the scales in their skin contain bony armored plates called
osteoderms. Loose flaps of granulated scales along their sides allow them to
breathe where the upper plated scales do not. They are long-tailed. Most anguids
have small toes. Some, like the glass lizard in the eastern U. S. have no legs at all.
Alligator lizards are terrestrial and are often found under wood and bark, or slinking
about in thick grass or underbrush. Not all Elgaria are tolerant of high temperatures,
so many prefer moister habitats. Anguids are capable of caudal autonomy, the
breaking off of the tail and its subsequent regeneration. Like all anguids, alligator
lizards are carnivorous: eating insects, arachnids, and other small invertebrates; the
larger southern species will also feed on other smaller lizards, and sometimes
small mammals, birds eggs and chicks.
Lizard and the Southern Alligator Lizard. Alligator lizards have elongated stiff bodies.
This is because the scales in their skin contain bony armored plates called
osteoderms. Loose flaps of granulated scales along their sides allow them to
breathe where the upper plated scales do not. They are long-tailed. Most anguids
have small toes. Some, like the glass lizard in the eastern U. S. have no legs at all.
Alligator lizards are terrestrial and are often found under wood and bark, or slinking
about in thick grass or underbrush. Not all Elgaria are tolerant of high temperatures,
so many prefer moister habitats. Anguids are capable of caudal autonomy, the
breaking off of the tail and its subsequent regeneration. Like all anguids, alligator
lizards are carnivorous: eating insects, arachnids, and other small invertebrates; the
larger southern species will also feed on other smaller lizards, and sometimes
small mammals, birds eggs and chicks.
What is the difference between a Northern and Southern?
bears live young while the Southern Alligator Lizard (Elgaria multicarinata) lays eggs.
This makes sense. The southern species is usually found in the hotter inlands,
while the northern appears in the colder coastal and coastal mountain areas. Many
reptile species living in cooler climates bear live young, for it isn't always easy to find
a consistently temperate egg incubation site; live bearers can incubate on the move!
Unfortunately, this major difference isn't always helpful in distinguishing species
since all the plumbing is on the inside.
Head shape might seem like a factor, but this is reserved for a comparison of the
sexes; males usually have larger and more triangular heads in both species.
The most obvious difference is scale colors and patterns, however these can often be
misleading when trying to determine both species and subspecies of the genus.
The Northern Alligator Lizard (Elgaria coerulea) is divided into four subspecies (2 in
our range):
San Francisco Alligator Lizard (E. coerulea coerulea)
Sierra Alligator Lizard (E. c. palmeri)
Northwestern Alligator Lizard (E. c. principis)
Shasta (E. c. shastae)
The Southern Alligator Lizard (Elgaria multicarinata) has three subspecies in
California (2 in our range, but we'll be covering all three):
California Alligator Lizard (E. multicarinata multicarinata)
Oregon Alligator Lizard (E. m. scincicauda)
San Diego Alligator Lizard (E. m. webbi)
The typical scale colors and patterns of each species may be generalized by the
following two pictures:
San Diego Alligator Lizard
(E. m. webbi) (Southern)
Eye color is also unique among the two species. Northerns have brown eyes.
Southerns have yellow eyes. Occasionally, however, I have difficulty distinguishing
the yellow-browns from the brownish-yellows.
Northerns are smaller, averaging a little over 5 inches (snout to vent) and just over 10
inches total with the tail. Southerns are larger at about 6 inches (snout to vent) and
up to 15 inches total; tails never broken are often more than twice the body length.
All alligator lizards have squarish scales. Scale keeling varies between subspecies.
In the northern species: the Northwestern and the Shasta have weakly keeled back
scales; those of the San Francisco and the Sierra are strongly keeled. In the
southern species the scalation on the upper forelegs may be noticable: While the
Oregon has smoothly scaled upper forelegs; the San Diego has keeled upper
forelegs.
Overall, body color and pattern, eye color, size, and scalation are not always a very
accurate means of identifying a species at first glance. Subspecies may interbreed
with one another where their boundaries overlap. Here the typical characteristics of
each subspecies may fuse into what one might call a subspecies hybrid. Where
intergadation occurs identification may be challenging.
An "easy" way to distinguish a Northern from a Southern is to turn the lizard over and
take a close look at its belly scales. Following the scale rows of the Northern you'll
see a faded dark line of pigment running down between each of the scale rows (at
each scale's side edge). A similar line of pigment is present in the Southern, only
these run down the middle of the scale rows (the middle of each subsequent scale).
Make sure you're in good light, for some of the lines may be very faint.
This makes sense. The southern species is usually found in the hotter inlands,
while the northern appears in the colder coastal and coastal mountain areas. Many
reptile species living in cooler climates bear live young, for it isn't always easy to find
a consistently temperate egg incubation site; live bearers can incubate on the move!
Unfortunately, this major difference isn't always helpful in distinguishing species
since all the plumbing is on the inside.
Head shape might seem like a factor, but this is reserved for a comparison of the
sexes; males usually have larger and more triangular heads in both species.
The most obvious difference is scale colors and patterns, however these can often be
misleading when trying to determine both species and subspecies of the genus.
The Northern Alligator Lizard (Elgaria coerulea) is divided into four subspecies (2 in
our range):
San Francisco Alligator Lizard (E. coerulea coerulea)
Sierra Alligator Lizard (E. c. palmeri)
Northwestern Alligator Lizard (E. c. principis)
Shasta (E. c. shastae)
The Southern Alligator Lizard (Elgaria multicarinata) has three subspecies in
California (2 in our range, but we'll be covering all three):
California Alligator Lizard (E. multicarinata multicarinata)
Oregon Alligator Lizard (E. m. scincicauda)
San Diego Alligator Lizard (E. m. webbi)
The typical scale colors and patterns of each species may be generalized by the
following two pictures:
San Diego Alligator Lizard
(E. m. webbi) (Southern)
Eye color is also unique among the two species. Northerns have brown eyes.
Southerns have yellow eyes. Occasionally, however, I have difficulty distinguishing
the yellow-browns from the brownish-yellows.
Northerns are smaller, averaging a little over 5 inches (snout to vent) and just over 10
inches total with the tail. Southerns are larger at about 6 inches (snout to vent) and
up to 15 inches total; tails never broken are often more than twice the body length.
All alligator lizards have squarish scales. Scale keeling varies between subspecies.
In the northern species: the Northwestern and the Shasta have weakly keeled back
scales; those of the San Francisco and the Sierra are strongly keeled. In the
southern species the scalation on the upper forelegs may be noticable: While the
Oregon has smoothly scaled upper forelegs; the San Diego has keeled upper
forelegs.
Overall, body color and pattern, eye color, size, and scalation are not always a very
accurate means of identifying a species at first glance. Subspecies may interbreed
with one another where their boundaries overlap. Here the typical characteristics of
each subspecies may fuse into what one might call a subspecies hybrid. Where
intergadation occurs identification may be challenging.
An "easy" way to distinguish a Northern from a Southern is to turn the lizard over and
take a close look at its belly scales. Following the scale rows of the Northern you'll
see a faded dark line of pigment running down between each of the scale rows (at
each scale's side edge). A similar line of pigment is present in the Southern, only
these run down the middle of the scale rows (the middle of each subsequent scale).
Make sure you're in good light, for some of the lines may be very faint.
Northern Alligator Lizard
Dorsal background varies in
shades of brown, tan, yellow,
olive, or gray. Sides are usually
barred, but some are muddled
and difficult to discern. Dorsal
patterns are often rowed with
spots, but some are crossbarred,
others barely have a dorsal
pattern. Dorsal scales are usually
in 16 rows.
The Shasta subspecies is an
exception to the norm. Males
will often have a bright orange-
tan-yellow background with
widely spaced dorsal and side
crossbars, and a gray head.
Females may have similar
crossbarring but not as much
color.
Southern Alligator Lizard
Dorsal and side backgrounds are
similar to northern species,
however the crossbars are many,
highly defined, often more
narrow, and often include brick
red coloration. Mid-body has 14
scale rows.
Dorsal background varies in
shades of brown, tan, yellow,
olive, or gray. Sides are usually
barred, but some are muddled
and difficult to discern. Dorsal
patterns are often rowed with
spots, but some are crossbarred,
others barely have a dorsal
pattern. Dorsal scales are usually
in 16 rows.
The Shasta subspecies is an
exception to the norm. Males
will often have a bright orange-
tan-yellow background with
widely spaced dorsal and side
crossbars, and a gray head.
Females may have similar
crossbarring but not as much
color.
Southern Alligator Lizard
Dorsal and side backgrounds are
similar to northern species,
however the crossbars are many,
highly defined, often more
narrow, and often include brick
red coloration. Mid-body has 14
scale rows.
Northwestern X Shasta Alligator Lizard
(E. coerulea principis) (Northern)
(E. coerulea principis) (Northern)
Northwestern Alligator Lizard
(E. coerulea principis)
Pigment is between scale
rows.
(E. coerulea principis)
Pigment is between scale
rows.
San Diego Alligator Lizard
(E. multicarinatus webbi)
Arrows indicate what appears to
be pigment within the scale rows
(not a good example)
The belly of the Oregon
Alligator Lizard (E. m.
scincicauda) [right]
is more definitive.
(E. multicarinatus webbi)
Arrows indicate what appears to
be pigment within the scale rows
(not a good example)
The belly of the Oregon
Alligator Lizard (E. m.
scincicauda) [right]
is more definitive.
| Our Northern Alligators |
The Northwestern Alligator Lizard (E. c. principis) ranges from So. British Columbia
(incl. Vancouver Island) south to No. Idaho, W. Montana, W-Central Washington and
Oregon, and of course NW California. It is here in Humboldt, Del Norte, Siskiyou,
and Trinity Counties (as well as extreme S-Central Oregon) where intergradation
occurs with the Shasta subspecies. They are found at elevations ranging from sea
level to 7,000 ft. (coniferous forests with openings - moist but not wet)
Both subspecies bear 2 to 8 live young between July and September.
Our personal experiences with E. c. principis here in Humboldt County have offered
some wonderful surprises. First, the coastal populations appear to be thriving. I've
spotted them in driftwood piles at Moonstone, Clam, Samoa, and Centerville
Beaches. Most specimens have the typical dark lateral checkering and light dorsal
crossbarring or spotting. One of our favorite places to go is "Stinky Beach" near the
mouth of the Elk River which empties into Humboldt Bay. There used to be a
rendering plant there, hence the name. A small peninsula northwest of the railroad
bridge over the Elk leads you to alligator lizard heaven. Flanked by bayside dunes on
the west side and river marsh on the east side, this strip of land offers plenty of cover
(grasses, shrubs,and alot of dry as well as moist and rotted driftwood) and lots to eat
(worms, millipedes, and insects - especially termites!) These lizards are frequently
discovered sharing their wooden retreats with Pacific Tree Frogs. The
Northwesterns are tolerant of cooler weather; we have seen them basking on logs in
60 degree weather in early February (2006). Many of the specimens found here
appear to show signs of intergradation with E. c. shastae; some of the males exhibit
the gray head and a brighter yellow body color. Our best find came in April of 2006
when we discovered an individual that appeared to be hypermelanistic, a mutation
where color and patterns are either eliminated or overwhelmed by an excessive
overproduction of melanin (black pigment). This specimen was all black above and
dark gray below.
The Shasta Alligator Lizard (E. c. shastae) may be found from So-Central Oregon
following the Cascades into No. California, south to the Sierras (where it meets E. c.
palmeri), and from So-Central Oregon its range also moves southwest through the
Klamath Mountains of Northwest California, and then south down the coastal mtns
where it crosses with the San Francisco ssp. E. c. coerulea. Isolated populations
have been found in the northern Great Basin (NE CA, So. OR, and NW NV). Sea level
to 7,000ft.
(incl. Vancouver Island) south to No. Idaho, W. Montana, W-Central Washington and
Oregon, and of course NW California. It is here in Humboldt, Del Norte, Siskiyou,
and Trinity Counties (as well as extreme S-Central Oregon) where intergradation
occurs with the Shasta subspecies. They are found at elevations ranging from sea
level to 7,000 ft. (coniferous forests with openings - moist but not wet)
Both subspecies bear 2 to 8 live young between July and September.
Our personal experiences with E. c. principis here in Humboldt County have offered
some wonderful surprises. First, the coastal populations appear to be thriving. I've
spotted them in driftwood piles at Moonstone, Clam, Samoa, and Centerville
Beaches. Most specimens have the typical dark lateral checkering and light dorsal
crossbarring or spotting. One of our favorite places to go is "Stinky Beach" near the
mouth of the Elk River which empties into Humboldt Bay. There used to be a
rendering plant there, hence the name. A small peninsula northwest of the railroad
bridge over the Elk leads you to alligator lizard heaven. Flanked by bayside dunes on
the west side and river marsh on the east side, this strip of land offers plenty of cover
(grasses, shrubs,and alot of dry as well as moist and rotted driftwood) and lots to eat
(worms, millipedes, and insects - especially termites!) These lizards are frequently
discovered sharing their wooden retreats with Pacific Tree Frogs. The
Northwesterns are tolerant of cooler weather; we have seen them basking on logs in
60 degree weather in early February (2006). Many of the specimens found here
appear to show signs of intergradation with E. c. shastae; some of the males exhibit
the gray head and a brighter yellow body color. Our best find came in April of 2006
when we discovered an individual that appeared to be hypermelanistic, a mutation
where color and patterns are either eliminated or overwhelmed by an excessive
overproduction of melanin (black pigment). This specimen was all black above and
dark gray below.
The Shasta Alligator Lizard (E. c. shastae) may be found from So-Central Oregon
following the Cascades into No. California, south to the Sierras (where it meets E. c.
palmeri), and from So-Central Oregon its range also moves southwest through the
Klamath Mountains of Northwest California, and then south down the coastal mtns
where it crosses with the San Francisco ssp. E. c. coerulea. Isolated populations
have been found in the northern Great Basin (NE CA, So. OR, and NW NV). Sea level
to 7,000ft.
Northwestern/Shasta intergrade
Elgaria coerulea principis X
shastae
"Stinky Beach"
Mouth of the Elk River
April 24, 2006
This feisty male was all dressed
up for spring!
Alligators lizards can be quite
nippy. When large Southerns
bite, the finger will flow!
Also, these guys are famous for
defecating while trying to
escape. Quite smelly!
Elgaria coerulea principis X
shastae
"Stinky Beach"
Mouth of the Elk River
April 24, 2006
This feisty male was all dressed
up for spring!
Alligators lizards can be quite
nippy. When large Southerns
bite, the finger will flow!
Also, these guys are famous for
defecating while trying to
escape. Quite smelly!
Good luck trying to ID juveniles.
The coloration is usually brownish
brick red AND patternless in both
species, although we've seen
some of the Southerns get their
crossbars early.
The coloration is usually brownish
brick red AND patternless in both
species, although we've seen
some of the Southerns get their
crossbars early.
Northwestern/Shasta
intergrade
intergrade
Northwestern/Shasta
intergrade
intergrade
San Diego Alligator Lizard
Northwestern - yearling
| California Alligator Lizard - pending |
Northwestern - Hypermelanistic
Information regarding individual species and subspecies names; geographical ranges and habitat;
color, pattern, and scale differences; and diet was cross-referenced using:
1. Pages 539-540, 542, and plates 445 and 448, The Audubon Society Field Guide to
2. Pages 57, 62, and 138-145, Reptiles of the Northwest, c .2002
3. Pages 331-333, and 492, Western Reptiles and Amphibians (3rd ed.) c. 2003.
Web1. www. embl-heidelberg.de/~uetz/families/Anguidae.html
Web2. www.animaldiversity.ummz.umich.edu/site/accounts/classification/Elgaria.html
color, pattern, and scale differences; and diet was cross-referenced using:
1. Pages 539-540, 542, and plates 445 and 448, The Audubon Society Field Guide to
2. Pages 57, 62, and 138-145, Reptiles of the Northwest, c .2002
3. Pages 331-333, and 492, Western Reptiles and Amphibians (3rd ed.) c. 2003.
Web1. www. embl-heidelberg.de/~uetz/families/Anguidae.html
Web2. www.animaldiversity.ummz.umich.edu/site/accounts/classification/Elgaria.html
Complete
| CLICK for information on our Southern Alligators! |
| Shasta Alligator Lizard |
Northwestern X Shasta
Subfamily - Gerrhonotinae
Genus - Elgaria
Genus - Elgaria
Elgaria
| (for both Northern and Southern Species) |
Northwestern Alligator tracks
