A Guide to the Amphibians
and Reptiles of California

Northern Alligator Lizard - Elgaria coerulea

Shasta Alligator Lizard - Elgaria coerulea shastensis

(Fitch, 1934)

Click on a picture for a larger view

Description • Taxonomy • Species Description • Scientific Name • Alt. Names • Similar Herps • References • Conservation Status

Northern Alligator Lizards California Range Map

Dark Blue: Range of this subspecies in California
Elgaria coerulea shastensis - Shasta Alligator Lizard

Range of other subspecies:

Red: Elgaria coerulea coerulea -
San Francisco Alligator Lizard

Orange: Elgaria coerulea palmeri -
Sierra Alligator Lizard

Purple: Elgaria coerulea principis -
Northwestern Alligator Lizard

Gray: Approximate area of intergradation

Click on the map for a topographical view

Map with California County Names

Adult with regenerated tail, Humboldt County

Adult missing its tail, Humboldt County

Adult with full tail, Humboldt County

Adult male with regenerated tail, Colusa County © James R. Buskirk

Gravid adult female with full tail, Siskiyou County

Adult with partly regenerated tail Humboldt County

Adult male, Siskiyou County
© Gene Sederholm

Underside of adult, Humboldt County
(Dark lines are inbetween
the rows of scales)

Underside of adult Humboldt County

Adult, inland Humbodt County
© Noah Morales

This interestingly-colored adult with a complete original tail was found in the mountains of northwestern Colusa County. © Sam Cartwright

Adult, Mendocino County
© James Morry

Adult male with a nice blue-gray head and a regenerated tail, Shasta County
© Steve Berry

The eye color of this sub-adult from the Humboldt County coast
is relatively light for the species. © Teejay ORear

This brilliantly-colored adult male was seen in Siskiyou County basking in the sun in April. © Eugene Sederholm. Notice that even its re-generated tail is bright yellow.

Adult male found in intergrade area with the San Francisco Alligator Lizard in Mendocino County. © Allen Vinson

This adult was found eating a huge Jerusalem Cricket in Mendocino County just north of the Sonoma County line in the intergrade area. © Jason McKinney

It is common to find blood-engorged ticks attached to alligator lizards, especially in and around the ear openings, as you can see on the Shasta Alligator Lizard on the left and on the San Francisco Alligator Lizard on the right.

Female: Left
Male: Right
Male alligator lizards have a larger, more triangular head than females, because they need stronger jaw muscles to bite and hold females and to fight rival males.
Sonoma County. © Laura Baker

Western Alligator Lizards, genus Elgaria, have large rectangular keeled scales on the back that are reinforced with bone.
(Elgaria multicarinata multicarinata is shown here).

Shasta Alligator Lizards With Atypical Color or Pattern

Dark (melanistic) adult with normal-colored adult, Humboldt County.
© Joe Eastham

Underside of melanistic adult, Humboldt County. © Joe Eastham

Breeding Behavior

An adult male Alligator Lizard from the intergrade zone in northern Sonoma County
courts a female by biting onto her neck in late May. © Laura Baker

Breeding male and female, Humboldt County. © Kelly Mathson

Adult male and female, Colusa County
© James R. Buskirk

Juveniles

Neonates, one day old, Siskiyou County

Recently-born juvenile, Humboldt County

Juvenile, Siskiyou County

Habitat

Habitat, Siskiyou County

Habitat, evergreen forest, Siskiyou County. (The gravid adult female shown above was found on the road at this spot.)

Habitat, logged evergreen forest Humboldt County

Habitat beach grassland,
Humboldt County

Short Videos

An adult Shasta Alligator Lizard in Humboldt County.

Juvenile Alligator Lizards look and move like a little skink. Here, a tiny recently-born Shasta Alligator Lizard races around on sandy ground then ducks back into the piece of driftwood it was hiding under.

This video shows how an alligator lizard's tail thrashes around after it has been dropped to distract a predator. The tail moved for about 4-5 minutes, which has been cut down here to about a minute, showing several different speeds until it is just barely moving.

Description

Size

Elgaria coerulea ranges from 2 3/4 - 5 7/8 inches in snout to vent length (7 - 13.6 cm) (Stebbins)

Appearance

Alligator lizards, genus Elgaria, are members of the family Anguidae, a family of lizards found in the Americas, Europe, Asia, and Africa.

They are characterized by a slim body with short limbs and long tail.

Large bony scales, a large head on an elongated body and powerful jaws probably give the lizards their common name.

The tail can reach twice the length of its body if it has never been broken off and regenerated.

Scales are keeled on the back, sides, and legs, with 16 rows of scales across the back at the middle of the body.
(Compare with the 14 rows of scales found on the Southern Alligator Lizard - Elgaria multicarinata.)

The dorsal scales are more weakly keeled than on other E. coerulea subspecies.
The temporals are weakly keeled.

A band of small granular scales separates the larger bone-reinforced scales on the back and on the belly, creating a fold along each side. These folds allow the body to expand to hold food, eggs, or live young. The fold contracts when the extra capacity is not needed.

The head of a male is broader than a female's with a more triangular shape.

Color and Pattern

Color is brown, grey, olive, or brown, above, with heavy dark blotches or irregular crossbands edged with white spots.
Body color may be yellowish with the head slate gray in some areas.
The underside can be bright yellow on some males.

Usually the dark bands on the back are so irregular that they cannot be counted.

Eyes

The eyes are relatively dark around the pupils compared with the light eyes of a similar species - the Southern Alligator Lizard - Elgaria multicarinata.

Lines on the Belly

Usually there are dark lines running lengthwise on the belly which run between the scales, along the edge of the scales.
(Compare with the underside lines on the Southern Alligator Lizard - Elgaria multicarinata which run through the middle of the scales.)

Identifying Alligator Lizards in California

Young

Newborn lizards are very thin and small, roughly 4 inches long, with smooth shiny skin with a plain tan, light brown, or copper colored back and tail. The sides are darker and sometimes mottled or barred as they are on adults. Juveniles gradually develop the large scales and heavy dark barring found on the back and tails of adults.

Life History and Behavior

Activity

Active during the day. Inactive during cold periods in winter.
Moves with a snake-like undulating motion.
A good swimmer, sometimes diving into the water to escape by swimming away.
Alligator lizards are generally secretive, tending to hide in brush or under rocks, although they are often seen foraging out in the open or on roads in the morning and evening.

Defense

The tail of an alligator lizard is easily broken off, as it is with many lizards.
The tail will grow back, although generally not as perfectly as the original.
A lizard may detach its tail deliberately as a defensive tactic. When first detached, the tail will writhe around for several minutes, long enough to distract a hungry predator away from the lizard.
More information about tail loss and regeneration.

Males sometimes also extrude the hemipenes when threatened.

Often when an alligator lizard is observed lying still or basking, it will tuck its legs back toward the body. This is probably a defensive measure to break up the outline of the lizard's body so that a predator can't tell that it's an animal with legs. This might be to give it the appearance of a stick or shadow or something not alive, or it might be to imitate a snake, since many animals are naturally afraid of snakes and will hesitate to approach or attack a snake.

Other defensive tactics used by alligator lizards are smearing the contents of the cloaca on the enemy and biting.
They often bite onto a predatory snake, on the neck or the head, rendering the snake unable to attack.
Samuel M. McGinnis (Stebbins & McGinnis, 2012) reports seeing a juvenile southern alligator lizard bite onto its own tail making itself impossible to be swallowed by a juvenile Alameda Striped Racer, which eventually gave up.

Diet and Feeding

Eats a variety of small invertebrates, including slugs, snails, and worms. Will also eat small lizards and small mammals. Occasionally feed on bird eggs and young birds. (Stebbins)

Reproduction

After mating, the female carries her young inside her until they are born live and fully-formed sometime between June and September.

During the spring breeding season, a male lizard grabs on to the head of a female with his mouth until she is ready to let him mate with her. They can remain attached this way for many hours, almost oblivious to their surroundings. Besides keeping her from running off to mate with another male, this probably shows her how strong and suitable a mate he is.

Habitat

Woodland, forests, grassland, coastal chaparral. Commonly found hiding under rocks, logs, bark, boards, trash, or other surface cover. Prefers wetter and cooler habitats than E. multicarinata, but generally found near sunny clearings.

Geographical Range

The subspecies Elgaria coerulea shastensis ranges from a zone of intergradation with E. c. coerulea in northern Sonoma County, north to northern Humboldt County, and east around the central valley into the Northern Sierra Nevada mountains. Isolated populations occur in the Warner Mountains. Also occurs in southern Oregon, with isolated populations occurring in southeastern Oregon and northwestern Nevada.

The species Elgaria coerulea ranges from Southern British Columbia south chiefly west of the Cascades and Coast Ranges to northern Monterey County, east into northern Idaho and northwestern Montana, with isolated populations occurring in southeastern Oregon, northwestern Nevada and the Warner Mountains in California, and south through the Sierra Nevada Mountains to Kern County.

Elevational Range

Stebbins (2003) shows the elevational range of the species Elgaria coerulea as sea level to around 10,500 ft. (3,200 m.) but only the subspecies E. c. palmeri can be found that high up. The other subspecies range much lower.

Notes on Taxonomy

In a study published in April, 2018 * Brian R. Lavin et al reported the results of sequencing mtDNA of Elgaria coerulea:

"Our phylogeographic examination of E. coerulea uncovered surprising diversity and structure, recovering 10 major lineages, each with substantial geographic substructure."
They did not recommend any taxonomic changes, but they did name the lineages and illustrate their distribution:

1. Pacific Northwest
2. Interior Coast Range
3. North Coast Ranges
4. South Coast Ranges
5. Northern California
6. Yolla Bolly Mountains
7. Lower Cascades
8. Central Sierra Nevada
9. Northern Sierra Nevada
10. Southern Sierra Nevada

"The taxon appears to have a Sierra Nevada origin and then moved both north and west to occupy its current distribution (as postulated 60 years ago), diversifying into a number of geographically confined clades along the way. The patterns of range limits and clade boundaries shared between E. coerulea and other codistributed forest and woodland species provides compelling evidence that a handful of major biogeographic barriers and historical events (e.g., San Francisco Bay and Monterey Bay outlets, Sierra Nevada glaciation) have been instrumental in shaping phylogeographic patterns and have likely influenced species range limits and even patterns of community assembly in the California Floristic Province."

* Brian R. Lavin, Guinivere O.U. Wogan, Jimmy A. McGuire, and Chris R. Feldman.
Phylogeography of the Northern Alligator Lizard (Squamata, Anguidae): Hidden diversity in a western endemic.
© 2018 Royal Swedish Academy of Sciences.
Zoologica Scripta. 2018; 1–15.

Alternate and Previous Names (Synonyms)

Elgaria coerulea shastensis - Shasta Alligator Lizard (Stebbins 2003)
Gerrhonotus coeruleus shastensis - Shasta Alligator Lizard (Smith 1946, Stebbins 1966, 1985)

Conservation Issues (Conservation Status)

None

Taxonomy
Family	Anguidae	Alligator Lizards & Allies	Gray, 1825
Genus	Elgaria	Western Alligator Lizards	Gray, 1838
Species	coerulea	Northern Alligator Lizard	Wiegmann, 1828
Subspecies	shastensis	Shasta Alligator Lizard	(Fitch, 1934)
Original Description
Elgaria coerulea - (Wiegmann, 1828) - Isis von Oken, Vol. 21, p. 380 Elgaria coerulea shastensis - (Fitch, 1934) - Copeia, p. 6 from Original Description Citations for the Reptiles and Amphibians of North America © Ellin Beltz
Meaning of the Scientific Name
Elgaria - obscure - possibly named for an "Elgar" or a pun on "alligator." coerulea - Latin - dark colored, dark blue - referring to the dorsal color of the type specimen shastensis - belonging to the Shasta Mountains - type locality is Shasta County, CA 1932 from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz
Related or Similar California Lizards
E. c. coerulea - San Francisco Alligator Lizard E. c. palmeri - Sierra Alligator Lizard E. c. principis - Northwestern Alligator Lizard E. m. multicarinata - California Alligator Lizard E. m. scincicauda - Oregon Alligator Lizard E. m. webbii - San Diego Alligator Lizard E. panamintina - Panamint Alligator Lizard
More Information and References
California Department of Fish and Wildlife Stebbins, Robert C., and McGinnis, Samuel M. Field Guide to Amphibians and Reptiles of California: Revised Edition (California Natural History Guides) University of California Press, 2012. Stebbins, Robert C. California Amphibians and Reptiles. The University of California Press, 1972. Flaxington, William C. Amphibians and Reptiles of California: Field Observations, Distribution, and Natural History. Fieldnotes Press, Anaheim, California, 2021. Samuel M. McGinnis and Robert C. Stebbins. Peterson Field Guide to Western Reptiles & Amphibians. 4th Edition. Houghton Mifflin Harcourt Publishing Company, 2018. Stebbins, Robert C. A Field Guide to Western Reptiles and Amphibians. 3rd Edition. Houghton Mifflin Company, 2003. Behler, John L., and F. Wayne King. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, 1992. Powell, Robert., Joseph T. Collins, and Errol D. Hooper Jr. A Key to Amphibians and Reptiles of the Continental United States and Canada. The University Press of Kansas, 1998. Bartlett, R. D. & Patricia P. Bartlett. Guide and Reference to the Turtles and Lizards of Western North America (North of Mexico) and Hawaii. University Press of Florida, 2009. Jones, Lawrence, Rob Lovich, editors. Lizards of the American Southwest: A Photographic Field Guide. Rio Nuevo Publishers, 2009. Smith, Hobart M. Handbook of Lizards, Lizards of the United States and of Canada. Cornell University Press, 1946.

Conservation Status
The following conservation status listings for this animal are taken from the April 2024 State of California Special Animals List and the April 2024 Federally Listed Endangered and Threatened Animals of California list (unless indicated otherwise below.) Both lists are produced by multiple agencies every year, and sometimes more than once per year, so the conservation status listing information found below might not be from the most recent lists. To make sure you are seeing the most recent listings, go to this California Department of Fish and Wildlife web page where you can search for and download both lists: https://www.wildlife.ca.gov/Data/CNDDB/Plants-and-Animals. A detailed explanation of the meaning of the status listing symbols can be found at the beginning of the two lists. For quick reference, I have included them on my Special Status Information page. If no status is listed here, the animal is not included on either list. This most likely indicates that there are no serious conservation concerns for the animal. To find out more about an animal's status you can also go to the NatureServe and IUCN websites to check their rankings. Check the current California Department of Fish and Wildlife sport fishing regulations to find out if this animal can be legally pursued and handled or collected with possession of a current fishing license. You can also look at the summary of the sport fishing regulations as they apply only to reptiles and amphibians that has been made for this website. This animal is not included on the Special Animals List, which indicates that there are no significant conservation concerns for it in California.
Organization	Status Listing	Notes
NatureServe Global Ranking
NatureServe State Ranking
U.S. Endangered Species Act (ESA)	None
California Endangered Species Act (CESA)	None
California Department of Fish and Wildlife	None
Bureau of Land Management	None
USDA Forest Service	None
IUCN

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