The Northern Alligator Lizard is a small lizard that resembles a
miniature alligator, from which the species gets its common name. Adults average 9.5
cm in length with females being slightly larger than males (Rutherford 2004). Males
have relatively wider heads than females, possibly for use during mating (see
Reproduction below). Their background colour is grey or tan marked by dark blotches,
and their bellies are white to gray (Fitch 1935). The young have a broad, bronze stripe
on their side. Adults have a distinctive fold of skink that runs along their sides; it helps
the body to expand when the lizard inflates itself with air or is distended by eggs or food.
Northern alligator lizards are live-bearing lizards with an average
of five young, ranging from two to eight (Rutherford 2002). Most males and females
breed the third spring after birth. Females may breed until seven years of age; males as
old as eight years of age have been captured. There are no mating displays; males
actively pursue females and hold the femaleʼs head in their jaws. Mating is likely a risky
undertaking as it may take place in the open and continue for up to twelve hours. Reproductive females are site-faithful; these sites may provide protection from
predators and necessary thermal requirements to complete gestation.
Northern Alligator Lizards are diurnal foragers and typically active in late afternoon. Adults eat
larger insects (beetles, caterpillars, and grasshoppers), spiders, snails, scorpions, and
millipedes. They will eat stinging and biting animals, although invertebrates having
offensive secretions seem to be avoided (Fitch 1935). It is likely that invertebrates are
consumed in available proportions, but food consumption in nature has not been studied. Newborn lizards likely eat smaller insects, although little is documented about their food habits, even in captivity (COSEWIC 2002).
Northern Alligator Lizards spend much of their time in retreat sites and are uncommon in the open (Rutherford and Gregory 2003). Adult males are most easily located in early spring during the breeding season, and gravid females are easily located in late summer on a cooler day.
In British Columbia, Northern Alligator Lizards emerge from
hibernation in mid-April. Mating takes place shortly after emergence from hibernation from mid-April to late-May. Young are born from mid-August to mid-September. Animals
enter hibernation in late-September (Rutherford 2002). The active period is extended in United States populations. At Creston, British Columbia, hibernation occurs in the summer habitat with no seasonal migration, although movement away from hibernation sites has been reported for some United States populations. They are site-faithful; individuals are typically recaptured within ten metres of a previous capture, both within a summer season and from year to year. Movements of greater than one hundred metres
are rare (Stewart 1985).
Northern Alligator Lizards can be found in a wide range of habitats: dry woodland, grassland, along the banks of creeks, and on ocean beaches (Fitch 1935).
They are often associated with rocky outcroppings, talus slopes, northern and montane
coniferous forests, and streams. In addition, this species thrives in disturbed areas, such as logging mills, hydrocuts and clearcuts, where there is an abundance of surface debris (Cook 1984). This species requires rocks and surrounding vegetation for hiding and they have high site-fidelity. Basking typically occurs in protected areas such as crevices or under rock cover (Rutherford and Gregory 2003). They are often found on forest edges or in forests but their association with forests is not clear. Hibernation requires access to rock crevices below the frost-line.
In Canada, Northern Alligator Lizards occur in southern British Columbia, north to Clearwater and
Stuie including eastern Vancouver Island and several Gulf Islands. They are found as far east as Creston, British Columbia. In the United States they are found south along the coasts of Washington, Oregon and California to Little Sur River in Monterrey County and in the Sierra Nevada past Sequoia National Forest, Kern County. They occur on several islands off the coasts of Washington and California. Their distribution extends east to the north tip of Idaho and northwestern Montana (COSEWIC 2002).
The site-fidelity and dependency on rock and vegetative cover makes
Northern Alligator Lizards vulnerable to modification of their localized habitat. Some habitat has been removed for road construction and quarrying. They are disturbed by people moving near
basking sites and this disturbance may be detrimental to gravid females. In addition, the
thermoregulatory constraints of gravid females means that a cool summer may reduce
reproductive output. There is likely little road mortality, although roads may act as
barriers. Illegal collecting appears minimal and not damaging to the population.
Predators include feral and domestic cats, in addition to natural predators such as
Rubber Boas and small raptors (COSEWIC 2002).
The subspecies present in British Columbia is the Northern Alligator Lizard
(Elgaria coerulea principis, Baird and Girard 1852). There are a variety of synonyms,
the most common being Gerrhonotus coeruleus principis (Fitch 1934).
Known predators of the Northern Alligator Lizard include: racers, rattlesnakes, garter snakes, rubber boas, shrikes, red-tailed hawks, and cats (Fitch 1935). Alligator Lizards use their tail as a decoyand are likely to drop (autotomize) their tail if captured.
Baird, S.F. and Girard, C. 1852. Description of new species of reptiles, collected by the U. S. Exploring Expedition under the command of Capt. Charles Wilkes, Proceedings National Academy of Sciences Philadelphia 6: 174-177.
Cook, F.R. 1984. Introduction to Canadian amphibians and reptiles. National Museums of Canada, Ottawa. 200 pp.
COSEWIC. 2002. COSEWIC Status Report on the Northern Alligator Lizard Elgaria in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 32 pp.
Fitch, H.S. 1935. Natural history of the alligator lizards. Transactions Academy Sciences St. Louis 29: 1-38.
Rutherford, P.L. 2002 . Costs of reproduction in a temperate-zone lizard, Elgaria coerulea. Ph.D. Thesis. University of Victoria, Victoria, British Columbia
Rutherford, P.L. 2004. Proximate mechanisms that contribute to female-biased sexual size dimorphism in an anguid lizard. Canadian Journal of Zoology 82 (5): 817-822.
Rutherford, P.L. and Gregory, P.T. 2003. Habitat use and movement patterns of northern alligator lizards (Elgaria coerulea) and western skinks (Eumeces skiltonianus) in southeastern British Columbia.Journal of Herpetology 37 (1): 98-106.
Stewart, J.R. 1985. Growth and survivorship in a California population of Gerrhonotus coeruleus, with comments on intraspecific variation in adult female size. American Midland Naturalist 113: 30-44.
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2021. E-Fauna BC:
Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab
for Advanced Spatial Analysis, Department of Geography, University of British
Columbia, Vancouver. [Accessed:
2022-08-13 8:30:19 PM]
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