Tuleyome's Science Corner - Western Fence Lizards

Kristie Ehrhardt • May 24, 2023

Western Fence Lizard (Sceloporus occidentalis)

The Western Fence Lizard (Sceloporus occidentalis) is a moderately sized lizard commonly found throughout the western United States from Eastern and Southwestern Oregon, Southwestern Idaho, Nevada, Western Utah, Arizona and Baja California from sea level to around 11,000 feet. They can be found in a variety of habitats within their range including woodlands, grasslands, chaparral, forests, and urban areas such as farmland and neighborhoods. They usually occur near water and do not occupy desert regions.


Lizards are commonly measured from snout to vent (STV) and Western Fence Lizards usually range from a little over two inches to about three and a half inches STV. This measurement does not include the tail as is common when measuring lizards because tail length of individuals can vary greatly. Coloration ranges from light to darker brown, gray or even jet black but it is believed that the color variation is less camouflage and more related to thermoregulation, the process that helps them maintain their core internal temperature. Because lizards are ectotherms (cold blooded), their body temperature depends on external heat sources such as sunlight itself or the surfaces of other things that are warm such as rocks or the ground. Western Fence Lizards are diurnal which means that they are active during the day and can often be seen in open, sunny areas basking in the sun on rocks, fallen trees, trail edges or fences. Because they like to bask in open areas, they are susceptible to predation and a cold lizard is a slow lizard - an easy snack for keen-sighted raptors and mammals.


They have sharp claws for climbing and their sharply pointed scales make them appear spiny. They have grayish stripes along the length of their body with a lighter sandy colored wave pattern going horizontally. You might have grown up calling Western Fence Lizards “blue bellies” for obvious reasons; the adult males have bright, blue bellies as well as blue patches on the underside of their necks. The blue is usually absent or very pale on females and juveniles which makes determining sex in adult lizards fairly easy. The shade of blue can range from almost shockingly blue to a lighter, pale blue. The undersides of the front and rear legs are yellow to orange and occasionally, lighter individuals can have some bright, iridescent turquoise blue scales on their backs. Males establish territories which usually includes higher areas where they can perch and keep an eye out for intruders. You may have seen them busting out a few pushups to threaten rival males (or maybe just a passerby) to keep them from their territory and they will engage in physical combat if the rival male does not heed the warning to stay away. Adult males also do pushups and bob their heads to show off their bright blue patches to impress females. Courtship and mating usually occur from March through July and females can lay up to three clutches of up to nearly 20 eggs. The eggs are laid in shallow depressions dug by the female in loose, moist soil and begin hatching in August. Keep an eye out around that time and you will probably start seeing teeny tiny little two-inch baby Western Fence Lizards scurrying for the nearest safe place. Most of them do not breed until their second spring and individuals can live from five to seven years in the wild if things go well for them.


Western Fence Lizards eat a variety of invertebrates such as spiders, caterpillars, crickets, grasshoppers, mosquitoes and sometimes even their own babies.


If their tail is nabbed by a predator, they can detach it in an attempt to escape. The discarded tail continues to wiggle which will hopefully distract the predator enough so the lizard can escape. The tail usually grows back in about a month but is almost always shorter and will have a different scale pattern. Although this may save the lizard’s life, it is very costly and stressful for them.


It’s been discovered that Western Fence Lizards have an immunity to Lyme disease. They have a protein in their blood that kills the bacteria that causes Lyme disease. When ticks carrying the bacteria feed on a Western Fence Lizard, the protein kills the bacteria in the tick’s gut and the tick can no longer spread the disease. It’s been shown that cases of Lyme disease are fewer in areas occupied by Western Fence Lizards. Pretty cool.


-Kristie Ehrhardt (kehrhardt@tuleyome.org)


Tuleyome Land Conservation Program Manager

RECENT ARTICLES

Policy Corner: The San Pablo Bay National Wildlife Refuge Expansion Act

By Diego Barraza • December 3, 2025
In October, Tuleyome hosted a community walking tour showcasing Mare Island’s southwestern coastal wetlands, a notable potion of the six distinct parcels proposed to be included in The San Pablo Bay National Wildlife Refuge Expansion Act. By law, National Wildlife Refuges overseen by U.S. Fish and Wildlife Service (USFWS), are legally mandated to conserve migratory bird and endangered species habitat while allowing for public access and recreation compatible with those mandates. This boundary expansion legislation is expected to be introduced in the 119 th Congress by Representative John Garamendi (D-CA-08), Jared Huffman (D-CA-02) and Mike Thompson (D-CA-04) and Senator Alex Padilla (D-CA). Approximately 6,934 new acres would be included in the boundary expansion. The boundary expansion aims to enhance the existing refuge’s 24,390 acres of essential wetland habitats along the coastlines of Sonoma, Solano, and Napa Counties. These tidal marshes, mud flats, and seasonal wetlands all host migratory birds, small mammals, and form the nursery grounds to sensitive fish species. Some iconic species include the California clapper rail, salt marsh harvest mouse, San Pablo song sparrow, and Suisun shrew. Current owners of the parcels that are proposed to be included within the refuge boundaries are the State Lands Commission, the State Coastal Conservancy, and the Sonoma Land Trust, all who support the proposal.

Monumental Questions - The United States Endangered Species Act

By Kristie Ehrhardt • December 3, 2025
You may have heard that there are some modifications brewing regarding the protections afforded species by the United States Endangered Species Act (ESA). Often regarded as one of the most powerful and effective (as well as sometimes controversial) environmental laws in the United States, the ESA was written into law with bipartisan support on December 28, 1973. The purpose of the ESA was to provide the infrastructure to conserve species and their habitats here in the United States and elsewhere. To date 99% of the species listed under the ESA have avoided becoming extinct. Under the law, organizations as well as individuals can petition to have a species listed as threatened or endangered under the ESA. The petitions then undergo extensive evaluation and review by scientists and the public prior to a decision being made about whether the species in question should be listed under the ESA. The ESA also requires that critical habitat areas also be protected as well as recovery plans be drafted for the species. Although this sounds very rigid, the law does allow for flexibility and requires coordination between federal, state, tribal and local agencies to conserve and protect species and their habitat. As the ESA currently stands, once a species is listed as threatened or endangered under the ESA, it and its habitat is afforded formal protection. Any impacts to the species itself or its habitat will likely require a permit and possibly remediation from the United States Fish and Wildlife Service or other leading agency. Under the required recovery plans, populations are monitored over several years to determine if efforts being made are aiding to its recovery. Once a species is considered recovered, it is removed from the special-status species list. Admittedly it is a long process but it is successful. One of the most illustrious delisting is that of the Bald Eagle ( Haliaectus leucocephalus ) in 2007 following the banning of dichlorodiphenyltrichloroethane (DDT) and a recovery period for the eagles. Another celebrated species that has been delisted from the ESA is the American Peregrine Falcon ( Falco peregrinus ) in 1999 following a captive breeding program and other intense conservation efforts. In 2016, more species were removed from the special-status species list than ever before. The other way that species can be removed from the special-status species list is if the decline has become irreversible and they are unfortunately classified as extinct. Habitat loss, overuse, competition from invasive non-native species and disease introduction are often human-caused and can be reversible if caught early enough. The goal of the ESA is to strengthen and highlight conservation efforts for species and their associated habitats. In addition to the ESA, the United States also works in cooperation with Migratory Bird Treaties with Canada, Mexico and Japan as well as the Convention on Nature Protection and Wildlife Preservation in the Western Hemisphere, the International Convention for the Northwest Atlantic Fisheries, the International Convention for the High Seas Fisheries of the North Pacific Ocean, the Convention on International Trade in Endangered Species of Wild Fauna and Flora and other international agreements. The ESA also offers assistance to states and other associated parties to develop and utilize conservation programs that meet national and international conservation standards for the best interest of the US citizens and our heritage in fish, wildlife and plants. The Berryessa Snow Mountain National Monument is home to several species protected under the ESA including the federally threatened Northern Spotted Owl ( Strix occidentallis caurina ), the federally endangered Pacific Marten ( Martes caurina ) and the Pacific Fisher ( Pekania pennanti ), the federally threatened California Coastal Chinook Salmon ( Oncorhynchus tshawytseha ) and the Northern California Steelhead ( Oncorhynchus mykiss indeas ).  -Kristie Ehrhardt ( kehrhardt@tuleyome.org ) Tuleyome Land Conservation Program Manager

Enjoying Outside! - Wild Turkeys

By Kristie Ehrhardt • December 3, 2025
Urban legend has it that our national symbol was nearly the Wild Turkey. Ben Franklin called them a “bird of courage” and it’s been said that he suggested that the Bald Eagle be replaced with a Wild Turkey. I’m not sure if that is true but I will say that after having a confrontation with the turkey brigade, they are not to be messed with. There are only two species of Wild Turkey world wide; the one we’re familiar with here in North America (Meleagris gallopavo) and the Ocellated Turkey (M. ocellata) found in Central America. For different reasons, the Wild Turkey is probably one of the most recognizable birds in the United States. Although I think they look best foraging under oak trees, some think they look even better on a platter surrounded by all the Thanksgiving accoutrements. Wild Turkeys are upland game birds and belong to the family Galliformes. The domesticated white turkey is a relative of our pretty Wild Turkey. Adult males have featherless red heads, long reddish-yellow legs with three toes facing forward and one rear-facing toe just below a nasty spur that they use to fight other males with. Their body feathers are generally dark brown and black with a stunning coppery sheen and a fan shaped tail. His iridescent feathers have areas of bronze, copper, green, gold, purple and red. Females on the other hand are about half the size of males and in following female upland game bird dress code, are mainly drab brown to camouflage while sitting on the nest. Ironically, this hefty brute that tries to intimate shoppers in the grocery store parking lot or corner toddlers in the neighborhood park was nearly extinct by the 20th century. By the early 1900’s only about 200,000 individuals were left roaming the country-sides of the United States due to habitat loss and over-hunting. Thanks to conservation efforts and responsible hunting practices, today their population is estimated at 6.5 billion wild birds in the United States. While several states have “turkey-rich refuges” here in California it seems that the birds have badgered their way into many of our urban and suburban areas. Wild Turkeys have funny appendages with funny names. The wattle is the skin flap that hangs from the beak to the neck and the snood is the piece of flesh that dangles from the beak. Can you guess what a caruncle is? Naturally, they’re the little bumps of flesh that cover the bird’s necks and heads. And of course we can’t forget about their beards - those are the bundle of stiff feathers that grow from their chests. All males have them and so do a few females but theirs is not nearly as glorious as the males’. The beard gets longer as the bird ages and biologists still don’t know what the purpose they serve. Very young turkeys are called poults and eat insects like they were gummy bears. As they age they develop a more refined and mature pallet and begin to incorporate some vegetation. Adult turkeys eat acorns, nuts, seeds, berries, insects and even small reptiles and amphibians. Young males are called jakes and adult males are called Toms while female turkeys are called hens. Wild Turkeys are highly adaptable and in California they can be found occupying a wide range of habitat types from oak woodlands, to mixed conifer forests, valley riparian, high deserts and even suburban parks and parking lots. You may find them pecking at their reflections in glass office complex doors, strutting around the post office parking lot or sitting on the hood of your car in the driveway. Fun Wild Turkey Facts! Wild Turkeys are much more agile than they appear. They have been clocked at 18 miles per hour on foot and can fly 50 to 60 miles per hour! Wild Turkeys have excellent vision and can see three times better than our perfect 20/20! They can change the color of their heads based on their mood! Although they’ve been called “courageous”, these softies sleep together in trees for safety. Males and female turkeys can be distinguished based on the size and shape of their droppings. Who knew? On average, adult Wild Turkeys have between five and six thousand feathers! When you’re walking off your Thanksgiving meal, keep an eye out for these beauties. Their habitat includes more than just your dinner table!  -Kristie Ehrhardt ( kehrhardt@tuleyome.org ) Tuleyome Land Conservation Program Manager