Elgaria coerulea
(Northern Alligator Lizard)

Key Characteristics

Lateral fold of skin

Elongate body

Brown (darkly pigmented) eyes

Dark edging on light colored ventral scales

General Description:
Northern Alligator Lizards are long-bodied lizards that are characterized by a distinct fold of skin (dorsolateral fold) that separates the keeled dorsal scales from the smooth ventral scales.  The scales in the region of the fold are granular and contrast with the scale types on either side.  These lizards are brown or brownish-green dorsally, and are light colored ventrally.  The ventral scales are edged laterally with a dark line (this is different from the Southern Alligator Lizard, which has a dark line running down the center of the ventral scales).  Northern Alligator Lizards have a somewhat triangular head with a pointed snout, and brown or darkly pigmented eyes.

Northern Alligator Lizards are medium sized, reaching sizes of around 100mm (4 in.) snout to vent length and 254mm (10 in.) total length (Nussbaum et al. 1983, Storm and Leonard 1995).  The fairly long tail is usually less than twice the body length (Stebbins 1985).

Northern Alligator Lizards are one of only two species of Idaho lizards that give birth to live young (viviparousClick word for definition) rather than laying eggs (oviparousClick word for definition).   The neonatesClick word for definition emerge from transparent membranes soon after birth.  The young lizards differ from adults by having a brassy or brownish-tan stripe dorsally that lacks much of the dark markings present on adults.

Northern Alligator Lizards are found in cooler and wetter environments than any other species of Idaho lizards.  They are often found in forest clearings or edges, under logs and other surface debris.  They can also be found in talus slopes that are associated with forests.

Idaho Distribution:
Northern Alligator Lizards are restricted to the northern portion of the state.  Along Pacific Coast, from southern British Columbia through Washington and Oregon to central California. Also in Rocky Mountains from British Columbia, southeast to northern Idaho and western Montana.

Feeds on insects, ticks, spiders, millipedes, and snails.

HibernatesClick word for definition in winter; duration of inactive period varies with local climate. Introduced cinnabar moths are poisonous to these lizards, and may have deleterious effects on northwestern populations. There are few records for this species in Idaho, possibly due to lack of surveys.

Mating apparently occurs in April and May. In the Northwest, populations at higher elevations nest later in summer than lower-altitude populations. Females, which reach sexual maturity in 32-44 mo in northern California, produce 1 litter. Litter size averages 4-6 eggs, depending on locality.



Unprotected nongame species

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Species description, key characteristics and original work by John Cossel Jr. © 1997
Species ecological information from Groves et al. ©1997.
Original images provided by Charles R. Peterson© 1998
Design and Optimization by Ean Harker©1999, 2000.
DAI layout by Stephen Burton, and Mike Legler © 1999.