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A Guide to the Amphibians
and Reptiles of California


Northwestern Alligator Lizard - Elgaria coerulea principis

(Baird and Girard, 1852)
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Northwestern Alligator Lizard Northwestern Alligator Lizard Northwestern Alligator Lizard
Adult, from near the Smith River, Del Norte County
Northwestern Alligator Lizard
Northwestern Alligator Lizard
Northwestern Alligator Lizard
Adult, Lake Earl, Del Norte County Adult, Lake Earl, Del Norte County Neonate, King County Washington
© Steven Caldwell
Northwestern Alligator Lizard Northwestern Alligator Lizard Northwestern Alligator Lizard
Adults, Del Norte County © Alan Barron
The range of this subspecies of Elgaria coerulea, barely extends into Califoria. Del Norte County is even considered an intergrade zone between two subspecies by some researchers. It is typical in intergrade zones to find animals that show characteristics of either subspecies. The lizards above were all found at the same location north of Crescent City, but the lizard on the left shows the appearance and scale count of E. c. principis, while the others are more similar in appearance to E. c. shastensis, the Shasta Alligator Lizard.
Northwestern Alligator Lizard Northwestern Alligator Lizard Northwestern Alligator Lizard
Adult, Siskiyou County. This one lacks the yellow coloring of the Shasta alligator lizard
and looks like it might be a mix of it - E. c. shastensis and E. c. principis.
Northwestern Alligator Lizard lizard with ticks Great Basin Collared Lizard
Adult, Klamath River, Del Norte County
© Alan Barron
It is common to find blood-engorged ticks attached to alligator lizards, especially around and behind the ears, as you can see on this Shasta Alligator Lizard. Western Alligator Lizards, genus Elgaria, have large rectangular keeled scales on the back that are reinforced with bone.
(Elgaria multicarinata multicarinata is shown here).
Tail Loss Defense
Northwestern Alligator Lizard Northwestern Alligator Lizard Northwestern Alligator Lizard
As a defensive measure , an alligator lizard may drop its tail, leaving it writhing on the ground. The writhing tail is intended to distract a predator. The loss of the tail does not harm the lizard. It will grow back.

Northern Alligator Lizards From Outside California
Adult, Kittitas County, Washington

Adult, Benton County, Oregon Sub-adult King County, Washington
Habitat
Northwestern Alligator Lizard Habitat Northwestern Alligator Lizard Habitat Northwestern Alligator Lizard Habitat
Habitat, Del Norte County

Habitat, Del Norte County Habitat, Del Norte County
Short Video
  Alligator Lizard Tail  
  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) E. c. principis is a small subspecies, usually less than 4 inches long (10.1 cm.)
Appearance
Alligator lizards, genus Elgaria, are members of the family Anguidae, a family of lizards found in the Americas, Europe, Asia, and Africa. Large bony scales, a large head on an elongated body and powerful jaws probably give the lizards their common name. They are characterized by a slim body with short limbs and long tail. The tail can reach twice the length of its body if it has never been broken off and regenerated.

Color is brown, grey, olive, or brown, above, with a broad band of olive-gray to brown down the middle of the back, sometimes with spots, and with darker sides mottled with dark spots. Typically there are no black scales wiith white tips on the sides. Markings do not form distinct bands or vertical bars.
Scales are keeled on the back, sides, and legs, with 14 rows of scales across the back at the middle of the body. 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 eyes are dark around the pupils. (Compare with the light eyes of Elgaria multicarinata .)
The head is usually not heavily mottled with dark color. The head of a male is broader than a female's with a more triangular shape.

Usually there are dark lines running lengthwise on the underside which run between the scales, along their edges. (Compare with the underside lines on Elgaria multicarinata which run through the middle of the scales.)
Young usually lack the dark barring and can have a plain copper or brownish band on the back.
Behavior
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.
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 from the lizard.
Other defensive tactics used by alligator lizards are smearing the contents of the cloaca on the enemy and biting. Males sometimes also extrude the hemipenes when threatened.

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.

May occur in concentrated colonies.
Diet
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
Young 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.
Range
In California, the subspecies Elgaria coerulea principis is only found in the extreme northwest in Del Norte and Siskiyou counties, and possibly northern Humboldt County. (Stebbins, 2003, shows this to be an intergrade zone.) Outside of California, the range extends north to British Columbia, including Vancouver Island, and east through northern Washington to extreme northwest Montana.

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 occuring in southeastern Oregon, northwestern Nevada and the Warner Mountains in California, and south through the Sierra Nevada Mountains to Kern County. From sea level to 10,500 ft. (3200 m)
Habitat
Woodland, forests, grassland. 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.
Taxonomic Notes
Formerly placed in the genus Gerrhonotus, with the Latin name Gerrholotus coeruleas principis.
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


principis Northwestern Alligator Lizard (Baird and Girard, 1852)
Original Description
Elgaria coerulea - (Wiegmann, 1828) - Isis von Oken, Vol. 21, p. 380
Elgaria coerulea principis - Baird and Girard, 1852 - Proc. Acad. Nat. Sci. Philadelphia, Vol. 6, p. 175

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
principis - Latin - first, leader or chief

from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz

Alternate Names
Northern Alligator Lizard

Formerly Gerrhonotus coeruleus principis

Related or Similar California Lizards
E. c. coerulea - San Francisco Alligator Lizard
E. c. palmeri - Sierra Alligator Lizard
E. c. shastensis - Shasta 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
Natureserve Explorer

California Dept. of Fish and Game

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.

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.

Smith, Hobart M. Handbook of Lizards, Lizards of the United States and of Canada. Cornell University Press, 1946.

Brown et. al. Reptiles of Washington and Oregon. Seattle Audubon Society,1995.

Nussbaum, R. A., E. D. Brodie Jr., and R. M. Storm. Amphibians and Reptiles of the Pacific Northwest. Moscow, Idaho: University Press of Idaho, 1983.

St. John, Alan D. Reptiles of the Northwest: Alaska to California; Rockies to the Coast. Lone Pine Publishing, 2002.


Conservation Status

The following status listings come from the Special Animals List and the Endangered and Threatened Animals List which are published by the California Department of Fish and Wildlife.


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
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

 

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