Alligator Lizard Fact Sheet

Alligator Lizard, Elgaria multicarinata
October 2008

Fact Summary
Taxonomy and Nomenclature
Distribution and Habitat
Physical Characteristics
Behavior and Ecology
Diet and Feeding
Reproduction and Development
Diseases and Pathology
Managed Care
Population and Conservation Status
Web Resources
Bibliography

TAXONOMY & NOMENCLATURE
(Macey et al 1999) (Wiens and Slingluff 2001)

Describer and Date: Weigmann 1828 for Elgaria; Blainville 1835 for Elgaria multicarinata; Baird 1858 for E. m. webbi (Proceedings of the Academy of Natural Sciences. Philadelphia 1858: 253-256)

Kingdom: Animalia
    Phylum: Chordata
        Class: Reptilia
             Order: Squamata
                Family: Anguidae
                    Subfamily: Gerrhonotinae
                           Genus: Elgaria
                                  Species: Elgaria multicarinata
                                        Subspecies: E. m. webbi (San Diego Alligator Lizard)
                                        Subspecies: E. m. multicarinata (California Alligator Lizard)
                                        Subspecies: E. m. scincicauda (Oregon Alligator Lizard)
                                        Subspecies: E. m. nana (Los Coronados Alligator Lizard)
                                        Subspecies: E. m. ignava (San Martin Alligator Lizard)

Taxonomic History and Nomenclature

Elgaria multicarinata formerly Gerrhonotus multicarinatus
Multicarinatus means "many keeled" referring to the ridge down the center of the scales
The San Diego Alligator Lizard subspecies named in honor of T.H. Webb who participated in the U.S. and Mexican Boundary Survey in the 1850's.
Many herpetologists today don't recognize subspecies, due to their lack of genetic distinctiveness

Phylogeny

Lizards in the anguid family originated in the northern hemisphere, sometime before 55 million years ago.
- 102 species and 15 genera in this family (Wiens and Slingluff 2001)
- Limbless or reduced-limb species have evolved many times in anguids (Wiens and Slingluff)
Fossils lizards in the sub-family Gerrhonotinae date at least to the early Eocene (50 to 55 million years ago) in North and Central America
Fossil anguids with strongly keeled scales such as Glyptosaurus are found in Eocene rocks in southern California and elsewhere
Southern species of the genus Elgaria became distinct from the northern species in the Miocene (around 6.6 million years ago)
Geographical barriers influenced the evolution of other species of Elgaria, especially (Macey et al 1999)
- Formation of the Gulf of California
- Climate change leading to formation of the Mojave desert
- Uplift of the California coastal mountains
By about 1.5 million years ago in the Pleistocene, E. multicarinata and E. panamintina became separate species.

DISTRIBUTION & HABITAT
(Hammerson & Hollingsworth IUCN 2008) (Stebbins 2003)
Distribution

Southern alligator lizards occur from Washington to northern Baja California, west of the Cascade-Sierra Nevada crest, including
- Islands off southern California and northern Baja California
- Isolated populations east of the Sierra Nevada mountains
Northern alligator lizards overlap much of the U.S. range of the southern species
Found at sea level to 2,286 m (7,500 ft)
Countries: United States and Mexico

Habitat:

Occupies coastal sage, chaparral, grasslands, oak woodlands, pinon-juniper woodlands, some pine woodlands, and forests.
In dry zones will be found in more abundant plant cover near water
Near human habitation, found under wood piles, rocks, debris
Most abundant in natural areas in denser ground cover where there are few open spaces (Kingsbury 1994)

PHYSICAL CHARACTERISTICS
(Ditmars 1933) (Lemm 2006) (Stebbins 1966) (Wiens and Slingluff 2001)

Body Length: Snout to Vent Length is 7.8 to 18.4 cm (3.1 to 7.25 in)
Tail Length: Up to twice the body length
General

Slender, snake-like body, short legs, large head with strong jaws, and a distinctive, slightly forked tongue (Lemm 2006)
General coloration on upper side: brown, gray, reddish or yellowish with dark vertical crossbars spotted with white

Sexual Dimorphism

Little difference between the sexes
- Some males have heads a little wider than females
- Males are not more than 10 % larger than females overall
- Difficult for observers to determine sex by casual inspection

Other Physical Characteristics

Like all members of the Anguid family, body covered with overlapping bony plates underneath the scales (Ditmars 1933)
Scales on belly are strongly keeled
A prominent skin fold runs down both sides the length of the body; this fold allows flexibility when lungs are expanded, when large volumes of prey consumed, and perhaps when eggs distend the body cavity (Stebbins 1966)
Yellow eyes (northern species have dark eyes)
Tongue slightly forked at tip
- Aids in gathering air-borne scents
- Odors are transferred to scent organ in roof of mouth (Ditmars 1933)

BEHAVIOR & ECOLOGY
(Brattstrom 1965) (Cowles 1946) (Kingsbury 1994) (Morey 2008) (Pough et al 1998)
(Rutherford & Gregory 2003) (Stebbins 1972)
Activity Cycle

Has ability to be active in cool temperatures during foggy or cloudy periods of the day.
- Can be active (and grow and digest food) with body temperature as low as 11° C (52° F) (Brattstrom 1965)
- Its capacity for activity despite low body temperature is distinctive. Many other lizards are 'obligate' thermoregulators and need to be warmer to function well. (Kingsbury 1994).
Active in the day (diurnal) or at dusk and dawn (crepuscular)

Territory/Range Size

Largely unknown for Southern Alligator Lizards, although may be similar to northern species
- Northern species studied by Rutherford and Gregory can be found under favored rocks and do not travel far throughout the year; only one out of 334 lizards moved as far as 750 m (slightly less than .5 mile)
- Northern species rarely found in the open; remain close to a rock and within 2 m (6.6 ft) of a shrub

Territorial Behavior

Largely unstudied although may be like the Northern Alligator Lizards which may have territorial behavior since they inhabit the same site for many years (are 'site tenacious') (Gillette 2008)

Vocalizations

Not the primary means of communication for lizards (Ditmars 1933).

Locomotion

Has snake-like undulating pattern to its locomotion on the ground
Is the most arboreal of the alligator lizards
A good swimmer; swim in serpentine manner rather than "dog-paddle" swimming (Cowles 1946)
Tail is slightly prehensile, helping hold onto branches when climbing
Tailless individuals run slower and are more secretive than ones with intact tails (Pough et al 1998)
Females with eggs are less mobile

Interspecies Interaction

Snakes, loggerhead shrikes, red-tailed hawks, domestic cats are predators on alligator lizards (Morey 2008)
- Around human habitations, cats killing of alligator lizards may lead to a significant increase in unwanted garden and yard 'pest' insects (which are food items for the lizards)
When threatened by a predator, alligator lizards open the mouth widely, showing teeth
When caught, bite strongly and may defecate on predator
When attacked or caught, quickly shed their tail
- Wriggling tail left behind distracts predators
- Losing a tail is energetically costly; may result in a missed reproductive season (Pough at al 1998)
Both Northern and Southern Alligator Lizards often found co-existing at same sites with Western Skinks ( Rutherford and Gregory 2003)
- Nature of the relationship with the skinks is unknown - perhaps it is competitive
- Southern Alligator Lizards are also known to eat Western Skinks (Cunningham 1956)

DIET & FEEDING
(Behler and King 1979) (Cunningham 1956) (King 1931) (Lemm 2006)

Carnivorous. Feed on wide variety of prey, anything they can catch and swallow; non-selective (Behler and King 1979)
Commonly take as prey: (Cunningham 2006)
- Insects and their larvae, especially ground beetles, grasshopper, crickets, ichneumon wasps
- Other arthropods, such as spiders (including black widow spiders), centipedes, scorpions, sow bugs
- Pulmonata snails
- Frog tadpoles
Also consume larger food items such as other lizards, especially Western Skinks
- Feeding on other lizards may be common because the alligator lizard can be active when other kinds of lizards need to rest
- May eat animals close to or greater than their own body length
Some reports suggest bird eggs eaten; other studies question this (Cunningham 1956)
Cannibalism not uncommon
- Adults eat young
- Adult males and females eat each other
Observation by naturalist: captive adult female consumed 20 grasshoppers, 11 katydid, 7 shield bugs and stink bug, and 3 spiders at a single feeding (King 1931)
Movement of prey helps to stimulate feeding behavior, but non-moving food consumed too such as spider egg contents, dead lizards, baby mice, and insects (Cunningham 1956)
Edible objects approached and inspected with the eyes (lizard moves head up and down, side-to side, or in small circles to judge size and distance away), then inspects with the tongue if possible
Ready to strike, the lizard arches its back upward, straightens the front limbs, bends the head and neck downwards, and attacks with a swift downward stroke (Cunningham 1956)

REPRODUCTION & DEVELOPMENT
(Burrage 1965) (Goldberg 1972) (Lemm 2006)
Courtship

Not well studied
Mating in early spring

Life Stages
Egg

Reports of females sharing egg-laying sites (Lemm 2006)
Significant differences exist for number of clutches between populations of Elgaria in different areas
Normally 5 to 20 eggs laid between May or June and July
Eggs are placed in rock crevices, burrows of rodents (Lemm 2006)

Hatchlings

Hatch after 11 weeks
34 mm, Snout Vent Length (1.3 in)
Weigh .55 grams (.12 lbs)

Young

Juveniles marked differently than adults: a broad stripe on the back of tan, reddish, yellow, gray, or beige; side bars may be less distinct

Adults

Sexual maturity reached at about 18 mos, 31 grams in weight

Longevity

10 to 15 years (Lemm, pers. communication)

Mortality

Snakes, loggerhead shrikes, red-tailed hawks, domestic cats are some reported predators on alligator lizards (Morey 2008)

DISEASES AND PATHOLOGY
(Goldberg & Bursey 1990) (Wright et al 1998)

Infections of parasitic roundworms (nematodes) Physaloptera sp. and Oswaldocruzia pipiens
Parasitic flatworms or tapeworms (cestodes) Baerietta gerrhonoti and Mesocestoides sp.
Host to Western Black Legged Ticks which may carry spirochete bacteria (Borrelia burgdorferi) that cause Lyme disease in humans
- Ticks may be difficult to detect because they may infest the lizard's ear openings
- One study suggests lizards themselves do not seem to be infected with the Lyme bacteria (Wright et al 1998)

MANAGED CARE

Survives well in captivity

POPULATION AND CONSERVATION STATUS
(IUCN 2008) (Lemm 2006) (Rutherford & Gregory 2003)
Conservation

IUCN Status: Least Concern (version 3.1)
IUCN Population Trend: Decreasing
CITES Status: Not listed

Threats to survival

Development and habitat destruction
Fire
Indiscriminate killing
Introduced species, including cats and dogs
Roads cutting through pathways (Lemm 2006) although movement patterns of northern species suggest site fidelity may lessen their vulnerability to presence of roads (Rutherford and Gregory 2003)

Important Web Resources:

IUCN Redlist 2008
University of Texas Digimorph Project: Two and 3-dimensional scans of Southern Alligator Lizard skull
Scientific and common names of reptiles and amphibians: Authored by writer and herpetologist Ellin Beltz
The TIGR Reptile Database: Provides "information on the classification of all living reptiles" sponsored in part by the German Herpetological Society

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