Overview
The Northern Alligator Lizard (Elgaria coerulea) is a remarkable, cold-adapted reptile that holds the northernmost distribution of any lizard in western North America. Resembling a miniature, plated alligator with its rectangular armored scales and distinct skin fold, it thrives in the cool, damp, mossy conifer forests of the Pacific Northwest, where it defies typical reptile biology by giving birth to live young instead of laying eggs.
Biology and Physical Characteristics
Elgaria coerulea possesses an elongated, slender body with short limbs and a long tail that can exceed the length of the body. Its dorsal scales are heavily keeled and rectangular, colored olive-brown, copper, or grey-green with dark checkered blotches down the back. A flexible granular skin fold runs along each lateral flank, expanding to accommodate large meals or developing embryos. Its eyes are distinctive, featuring bright pale blue to grey irises.
Behavior and Ecology
Uniquely adapted to foggy, chilly Pacific climates, the Northern Alligator Lizard actively forages at ambient temperatures that would paralyze most other reptiles. In late summer, females give birth to 3 to 15 fully formed live young (viviparity), an evolutionary adaptation that protects developing embryos from cold northern ground soils. If seized by a predator, it detaches its tail (autotomy), which thrashes violently while the lizard escapes.
Conservation and Human Impact
Classified as Least Concern by the IUCN, the Northern Alligator Lizard is common throughout protected provincial and state parks from Vancouver Island to the Sierra Nevada. It adapts well to suburban woodland edges, rock gardens, and woodpiles, providing natural pest control by consuming garden slugs and beetles.
Interesting Factoid
The Northern Alligator Lizard gives birth to live babies rather than laying eggs; carrying her embryos internally allows the mother to sunbathe on warm rocks, keeping her developing babies warm in chilly Pacific Northwest climates.