Arbutus menziesii, the Pacific madrone or madrona, is a species of tree in the family Ericaceae, native to the western coastal areas of North America, from British Columbia to California. It is known as the madroa, madroño, madroña, or bearberry; the name "strawberry tree" may be found in relation to A. menziesii. According to the Sunset Western Garden Book, in the United States, the name "madrone" is more common south of the Siskiyou Mountains of southern Oregon and Northern California and the name "madrona" is more common north of the Siskiyous; the Concow tribe calls the tree dis-tā' - kou-wät ′ - chu. In British Columbia it is referred to as arbutus, its species name was given it in honour of the Scottish naturalist Archibald Menzies, who noted it during George Vancouver's voyage of exploration. Arbutus menziesii is an evergreen tree with rich orange-red bark that when mature peels away in thin sheets, leaving a greenish, silvery appearance that has a satin sheen and smoothness. In spring, it bears sprays of small bell-like flowers, in autumn, red berries.
The berries have hooked barbs that latch onto larger animals for migration. It is common to see madronas of about 10 to 25 metres in height, but with the right conditions trees may reach up to 30 metres. In ideal conditions madronas can reach a thickness of 5 to 8 feet at the trunk, much like an oak tree. Leaves are thick with a waxy texture, oval, 7 to 15 centimetres long and 4 to 8 centimetres broad, arranged spirally; the leaves are evergreen, lasting a few years before detaching, but in the north of its range, wet winters promote a brown to black leaf discoloration due to fungal infections. The stain lasts until the leaves detach at the end of their lifespan. Madrones are native to the western coast of North America, from British Columbia to California, they are found in Puget Sound, the Oregon Coast Range, California Coast Ranges. They are rare south of Santa Barbara County, with isolated stands south to Palomar Mountain in California. One author lists their southern range as extending as far as Baja California in Mexico, but others point out that there are no recorded specimens collected that far south, the trees are absent from modern surveys of native trees there.
However other Arbutus species are endemic to the area. The trees are difficult to transplant and a seedling should be set in its permanent spot while still small. Transplant mortality becomes significant; the site should be sunny, well drained, lime-free. In its native range, a tree needs no food once it has become established. Water and nitrogen fertilizer will boost its growth, but at the cost of making it more susceptible to disease; this plant has gained the Royal Horticultural Society's Award of Garden Merit. Native Americans ate the berries, but because the berries have a high tannin content and are thus astringent, they more chewed them or made them into a cider, they used the berries to make necklaces and other decorations, as bait for fishing. Bark and leaves were used to treat stomach aches, skin ailments, sore throats; the bark was made into a tea to be drunk for these medicinal purposes. Many mammal and bird species feed off the berries, including American robins, cedar waxwings, band-tailed pigeons, varied thrushes, mule deer, ring-tailed cats, bears.
Mule deer will eat the young shoots when the trees are regenerating after fire. It is important as a nest site for many birds, in mixed woodland it seems to be chosen for nestbuilding disproportionately to its numbers; the wood is durable and has a warm color after finishing, so it has become more popular as a flooring material in the Pacific Northwest. An attractive veneer can be made from the wood. However, because large pieces of madrona lumber warp and unpredictably during the drying process, they are not used much. Madrone is burned for firewood, since it is a hard and dense wood that burns long and hot, surpassing oak in this regard. Although drought tolerant and fast growing, Arbutus menziesii is declining throughout most of its range. One cause is fire control. Mature trees survive fire, can regenerate more after fire than the Douglas firs with which they are associated, they produce large numbers of seeds, which sprout following fire. Increasing development pressures in its native habitat have contributed to a decline in the number of mature specimens.
This tree is sensitive to alteration of the grade or drainage near the root crown. Until about 1970, this phenomenon was not recognized on the west coast; the species is affected to a small extent by sudden oak death, a disease caused by the water-mold Phytophthora ramorum. During the Soberanes Fire in the summer of 2016, the largest known specimen of madrone was burned and killed; the tree, 125 feet tall and more th
The acorn woodpecker is a medium-sized woodpecker, 21 cm long, with an average weight of 85 g. The adult acorn woodpecker has a brownish-black head, back and tail, white forehead, throat and rump; the eyes are white. There is a small part on the small of their backs; the adult male has a red cap starting at the forehead, whereas females have a black area between the forehead and the cap. The white neck and forehead patches are distinctive identifiers; when flying, they take a few flaps of their wings and drop a foot or so. White circles on their wings are visible. Acorn woodpeckers have a call that sounds like they are laughing. A kind of cancer has killed many Acorn woodpeckers. Scientists are working to help them. Acorn woodpeckers, as their name implies, depend on acorns for food. In some parts of their range, the woodpeckers create granaries or "acorn trees" by drilling holes in dead trees, dead branches, telephone poles, wooden buildings, they drill holes in the thick bark of mature living trees, notably the Ponderosa Pine in California.
These holes, always above the snow line so that the acorns can be retrieved in winter, can be observed in the hundreds on large trees. They do not harm the tree; the woodpeckers collect acorns and find a hole, just the right size for the acorn. As acorns dry out, they are moved to smaller holes and granary maintenance requires a significant amount of the bird's time, they feed on insects and fruit. The acorns are visible, the group defends the tree against potential cache robbers like Steller's jays and western scrub jays. Acorns are such an important resource to the California populations that acorn woodpeckers may nest in the fall to take advantage of the fall acorn crop, a rare behavior in birds. Acorn woodpeckers can be seen sallying from tree limbs to catch insects, eating fruit and seeds, drilling holes to drink sap; the acorn woodpecker will use any human-made structures to store acorns, drilling holes into fence posts, utility poles and automobile radiators. The woodpecker will put acorns into places where it cannot get them out.
Woodpeckers put 220 kg of acorns into a wooden water tank in Arizona. In parts of its range the acorn woodpecker does not construct a "granary tree", but instead stores acorns in natural holes and cracks in bark. If the stores are eaten, the woodpecker will move to another area going from Arizona to Mexico to spend the winter. Acorn woodpeckers practice cooperative breeding, a rare evolutionary trait, thought to occur in only nine percent of bird species. Cooperative breeding is defined as more than two birds taking care of nestlings in the nest. With the acorn woodpecker, cooperative breeding occurs in two ways: family groups. Coalitions of adult acorn woodpeckers nest together. Additionally, adult offspring stay in their parents' nest and help raise the next generation of woodpeckers, it is believed that limited territories drive cooperative breeding behavior in birds, in the case of the acorn woodpecker, this limited territory is the acorn storage granary. As mentioned, adult acorn woodpeckers live together in "coalitions", which consist of up to seven co-breeding males and up to three joint-nesting females.
Nesting groups can contain up to ten offspring helpers. These breeding coalitions are closely related; the males are brothers, the females are sisters. Inbreeding is rare, meaning that co-breeders of the opposite sex are never related. In groups with more than one breeding female, the females put their eggs into a single nest cavity. A female destroys any eggs in the nest before she starts to lay. Once all the females start to lay, they stop removing eggs. Acorn woodpeckers, like many other species, are threatened by habitat degradation. Competition for nest cavities by non-native species is an ongoing threat in urbanized areas. Conservation of this species is dependent on the maintenance of functional ecosystems that provide the full range of resources upon which the species depends; these include mature forests with oaks capable of producing large mast crops and places for the woodpeckers to nest and store mast. Residents are encouraged to preserve mature oak and pine-oak stands of trees and to provide dead limbs and snags for nesting and granary sites to help preserve the acorn woodpecker's population.
Walter Lantz is believed to have patterned the call of his cartoon character Woody Woodpecker on that of the acorn woodpecker, while patterning his appearance on that of the pileated woodpecker which has a prominent crest. Haydock J. Koenig W. D. & Stanback, M. T.. Shared parentage and incest avoidance in the cooperatively breeding acorn woodpecker. Molecular Ecology, 10, 1515-1525. Stiles, F Gary. Internet Bird Collection. Stamps with Range Map at bird-stamps.org Acorn woodpecker photo gallery at VIREO Acorn woodpecker at the US Fish & Wildlife Service Digital Repository
Sonoma County, California
Sonoma County is a county in the U. S. state of California. As of the 2010 United States Census, its population was 483,878, its county seat and largest city is Santa Rosa. It is to the south of Mendocino County, it is west of Lake County. Sonoma County comprises the Santa Rosa, CA Metropolitan Statistical Area, included in the San Jose-San Francisco-Oakland, CA Combined Statistical Area, it is the northwesternmost county in the nine-county San Francisco Bay Area region. Sonoma is the southwestern county and largest producer of California’s Wine Country region, which includes Napa and Lake counties, it possesses thirteen approved over 250 wineries. In 2002, Sonoma County ranked as the 32nd county in the United States in agricultural production; as early as 1920, Sonoma County was ranked as the eighth most agriculturally productive US county and a leading producer of hops, prunes and dairy and poultry products due to the extent of available, fertile agricultural land in addition to the abundance of high quality irrigation water.
More than 7.4 million tourists visit each year, spending more than $1 billion in 2006. Sonoma County is the home of Santa Rosa Junior College. Sonoma County is home to several Native American tribes. By the 1830s, European settlement had set a new direction that would prove to radically alter the course of land use and resource management of this region. Sonoma County has rich agricultural land, albeit divided between two nearly monocultural uses as of 2007: grapes and pasturage; the voters have twice approved open space initiatives that have provided funding for public acquisition of natural areas, preserving forested areas, coastal habitat, other open space. The Pomo, Coast Miwok and Wappo peoples were the earliest human settlers of Sonoma County, between 8000 and 5000 BC living within the natural carrying capacity of the land. Archaeological evidence of these First people includes a number of occurrences of rock carvings in southern Sonoma County. Spaniards and other Europeans claimed and settled in the county from the late 16th to mid-19th century, seeking timber and farmland.
The Russians were the first newcomers to establish a permanent foothold in Sonoma County, with the Russian-American Company establishing Fort Ross on the Sonoma Coast in 1812. This settlement and its outlying Russian settlements came to include a population of several hundred Russian and Aleut settlers and a stockaded fort with artillery. However, the Russians abandoned it in 1841 and sold the fort to John Sutter and Mexican land grantee of Sacramento; the Mission San Francisco Solano, founded in 1823 as the last and northernmost of 21 California missions, is in the present City of Sonoma, at the northern end of El Camino Real. El Presidio de Sonoma, or Sonoma Barracks, was established in 1836 by Comandante General Mariano Guadalupe Vallejo, his duties included keeping an eye on the Russian traders at Fort Ross, secularizing the Mission, maintaining cooperation with the Native Americans of the entire region, doling out the lands for large estates and ranches. The City of Sonoma was the site of the Bear Flag Revolt in 1846.
Sonoma was one of the original counties formed when California became a state in 1850, with its county seat the town of Sonoma. However, by the early 1850s, Sonoma had declined in importance in both commerce and population, its county buildings were crumbling, it was remote; as a result, elements in the newer growing towns of Petaluma, Santa Rosa, Healdsburg began vying to move the county seat to their towns. The dispute was between the bigger, richer commercial town of Petaluma and the more centrally located, growing agricultural center of Santa Rosa; the fate was decided following an election for the state legislature in which James Bennett of Santa Rosa defeated Joseph Hooker of Sonoma and introduced a bill that resulted in Santa Rosa being confirmed as county seat in 1854. Several Santa Rosans, not caring to wait, decided to take action and, one night, rode down the Sonoma Valley to Sonoma, took the county seals and records, brought them to Santa Rosa; some of the county's land was annexed from Mendocino County between 1850 and 1860.
Early post-1847 settlement and development focused on the city of Sonoma the region's sole town and a common transit and resting point in overland travel between the region and Sacramento and the gold fields to the east. However, after 1850, a settlement that soon became the city of Petaluma began to grow near the farthest navigable point inland up the Petaluma River. A hunting camp used to obtain game to sell in other markets, by 1854 Petaluma had grown into a bustling center of trade, taking advantage of its position in the river near a region of productive agricultural land, being settled. Soon, other inland towns, notably Santa Rosa and Healdsburg began to develop due to their locations along riparian areas in prime agricultural flatland. However, their development lagged behind Petaluma which, until the arrival of railroads in the 1860s, remained the primary commercial and break-of-bulk point for people and goods in the region. After the arrival of the San Francisco and North Pacific Railroad in 1870, Santa Rosa began to boom, soon equalling and surpassing Petaluma as the region's population and commercial center.
The railroad bypassed Petaluma for southern connections to ferries of San Francisco Bay. Six nations have claimed Sonoma County fro
Chaparral is a shrubland or heathland plant community found in the US state of California and in the northern portion of the Baja California Peninsula, Mexico. It is shaped by a Mediterranean climate and wildfire, featuring summer-drought-tolerant plants with hard sclerophyllous evergreen leaves, as contrasted with the associated soft-leaved, drought-deciduous, scrub community of coastal sage scrub, found below the chaparral biome. Chaparral covers 5% of the state of California and associated Mediterranean shrubland an additional 3.5%. The name comes for evergreen oak shrubland. In its natural state, chaparral is characterized by infrequent fires, with intervals ranging between 30-150+ years. Mature chaparral is characterized by dense thickets; these plants are flammable during the late summer and autumn months when conditions are characteristically hot and dry. They grow as woody shrubs with thick and small leaves, contain green leaves all year, are drought resistant. After the first rains following a fire, the landscape is dominated by small flowering herbaceous plants, known as fire followers, which die back with the summer dry period.
Similar plant communities are found in the four other Mediterranean climate regions around the world, including the Mediterranean Basin, central Chile, the South African Cape Region, in Western and Southern Australia. According to the California Academy of Sciences, Mediterranean shrubland contains more than 20 percent of the world's plant diversity; the word chaparral is a loan word from Spanish chaparro, meaning both "small" and "dwarf" evergreen oak, which itself comes from a Basque word, that has the same meaning. Conservation International and other conservation organizations consider chaparral to be a biodiversity hotspot – a biological community with a large number of different species –, under threat by human activity; the California chaparral and woodlands ecoregion, of the Mediterranean forests and scrub biome, has three sub-ecoregions with ecosystem—plant community subdivisions: California coastal sage and chaparral:In coastal Southern California and northwestern coastal Baja California, as well as all of the Channel Islands off California and Guadalupe Island.
California montane chaparral and woodlands:In southern and central coast adjacent and inland California regions, including covering some of the mountains of the California Coast Ranges, the Transverse Ranges, the western slopes of the northern Peninsular Ranges. California interior chaparral and woodlands:In central interior California surrounding the Central Valley, covering the foothills and lower slopes of the northeastern Transverse Ranges and the western Sierra Nevada range. For the numerous individual plant and animal species found within the California chaparral and woodlands ecoregion, see: Flora of the California chaparral and woodlands Fauna of the California chaparral and woodlands; some of the indicator plants of the California chaparral and woodlands ecoregion include: Quercus species – oaks: Quercus agrifolia – coast live oak Quercus berberidifolia – scrub oak Quercus chrysolepis – canyon live oak Quercus douglasii – blue oak Quercus wislizeni – interior live oak Artemisia species – sagebrush: Artemisia californica – California sagebrush, coastal sage brush Arctostaphylos species – manzanitas: Arctostaphylos glauca – bigberry manzanita Arctostaphylos manzanita – common manzanita Ceanothus species – California lilacs: Ceanothus cuneatus – buckbrush Ceanothus megacarpus – bigpod ceanothus Rhus species – sumacs: Rhus integrifolia – lemonade berry Rhus ovata – sugar bush Eriogonum species – buckwheats: Eriogonum fasciculatum – California buckwheat Salvia species – sages: Salvia mellifera – black sage Another phytogeography system uses two California chaparral and woodlands subdivisions: the cismontane chaparral and the transmontane chaparral.
Cismontane chaparral refers to the chaparral ecosystem in the Mediterranean forests and scrub biome in California, growing on the western sides of large mountain range systems, such as the western slopes of the Sierra Nevada in the San Joaquin Valley foothills, western slopes of the Peninsular Ranges and California Coast Ranges, south-southwest slopes of the Transverse Ranges in the Central Coast and Southern California regions. In Central and Southern California chaparral forms a dominant habitat. Members of the chaparral biota native to California, all of which tend to regrow after fires, include: Adenostoma fasciculatum, chamise Adenostoma sparsifolium, redshanks Arctostaphylos spp. manzanita Ceanothus spp. ceanothus Cercocarpus spp. mountain mahogany Cneoridium dumosum, bush rue Eriogonum fasciculatum, California buckwheat Garrya spp. silk-tassel bush Hesperoyucca whipplei, yucca Heteromeles arbutifolia, toyon Acmispon glaber, deerweed Malosma laurina, laurel sumac Marah macrocarpus, wild cucumber Mimulus aurantiacus, bush monkeyflower Pickeringia montana, chaparral pea Prunus ilicifolia, islay or hollyleaf cherry Quercus berberidifolia, scrub oak Q. dumosa, scrub oak Q. wislizenii var. frutescens Rhamnus californica, California coffeeberry Rhus integrifolia, lemonade berry Rhus ovata, sugar bush Salvia apiana, white sage Salvia mellifera, black sage Xylococcus bicolor, mission manzanita The complex ecology of chaparral habitats supports a large number of animal species.
In biology, the canopy is the aboveground portion of a plant community or crop, formed by the collection of individual plant crowns. In forest ecology, canopy refers to the upper layer or habitat zone, formed by mature tree crowns and including other biological organisms. Sometimes the term canopy is used to refer to the extent of the outer layer of leaves of an individual tree or group of trees. Shade trees have a dense canopy that blocks light from lower growing plants. Canopy structure is the spatial arrangement of a plant canopy. Leaf Area Index, leaf area per unit ground area, is a key measure used to understand and compare plant canopies, it is taller than the understory layer. Dominant and co-dominant canopy trees form the uneven canopy layer. Canopy trees are able to photosynthesize rapidly due to abundant light, so it supports the majority of primary productivity in forests; the canopy layer provides protection from strong winds and storms, while intercepting sunlight and precipitation, leading to a sparsely vegetated understory layer.
Forest canopies are home to unique fauna not found in other layers of forests. The highest terrestrial biodiversity resides in the canopy of tropical rainforests. Many rainforest animals have evolved to live in the canopy, never touch the ground; the canopy of a rainforest is about 10m thick, intercepts around 95% of sunlight. The canopy is below the emergent layer, a sparse layer of tall trees one or two per hectare. With an abundance of water and a near ideal temperature in rainforests and nutrients are two factors that limit tree growth from the understory to the canopy. In the permaculture and forest gardening community, the canopy is the highest of seven layers. Canopy Canopy research Canopy walkway Hemispherical photography Stratification Treefall gap Wildfire Crown shyness Tropical forest Rainforest size-asymmetric competition Lowman, M. D. and H. B. Rinker. 2004. Forest Canopies. Academic Press. ISBN 0-12-457553-6, ISBN 978-0-12-457553-0 Moffett, M. W. 1994. The High Frontier: Exploring the Tropical Rainforest Canopy.
Harvard University Press, Cambridge, MA. Russell, G. B. Marshall, P. G. Jarvis. 1990. Plant Canopies: Their Growth and Function. Cambridge University Press. ISBN 0-521-39563-1, ISBN 978-0-521-39563-2 International Canopy Access Network
The Steller's jay is a jay native to western North America related to the blue jay found in the rest of the continent, but with a black, blackish-brown or dark blue head and upper body. It is known as the long-crested jay, mountain jay, pine jay, it is the only crested jay west of the Rocky Mountains. Steller's jay shows a great deal of regional variation throughout its range. Blackish-brown-headed birds from the north become bluer-headed farther south; the Steller's jay has a more slender bill and longer legs than the blue jay and has a much more pronounced crest. It is somewhat larger; the head is blackish-brown, black or dark blue, depending on the latitude of the bird, with lighter streaks on the forehead. This dark coloring gives way from lower breast to silvery blue; the primaries and tail are a rich blue with darker barring. Birds in the eastern part of its range along the Great Divide have white markings on the head over the eyes; this bird is named after the German naturalist Georg Wilhelm Steller, the first European to record them in 1741.
Steller's jay is one of two species in the other species being the blue jay. There are 17 subspecies of Steller's jays ranging from Alaska to Nicaragua, with 8 found north of Mexico with areas of low or non-existent presence of the species separating the subspecies. At least some of the variation in the species is due to different degrees of hybridization between Steller's jays and blue jays. To name a few: C. s. macrolopha C. s. stelleri C. s. carlottae, the largest subspecies. The genus Cyanocitta is part of the family Corvidae, which consists of the crows, rooks, jays, treepies and nutcrackers; the Steller's jay occurs in most of the forested areas of western North America as far east as the eastern foothills of the Rocky Mountains from southern Alaska in the north to northern Nicaragua replacing the blue jay prevalent on the rest of the continent in those areas. Its density is lower in the central Rocky Mountain region plus the desert or scrubland areas of the Great Basin; some hybridization with the blue jay in eastern foothills of the Rocky Mountains Colorado, has been reported.
Although the Steller's jay lives in coniferous forests it can be found in other types of forests as well. They can be found from low to moderate elevations, on rare occasions to as high as the tree line. Steller's jays are common in agricultural areas with nearby forests. Steller's jays are omnivores, they gather food both from trees. The Steller's jay's diet includes a wide range of seeds, nuts and other fruit, they eat many types of invertebrates, small rodents and nestlings such as those of the marbled murrelet. There are some accounts of them eating both snakes and lizards. Acorns and conifer seeds are staples during the non-breeding season, they exploit human-provided food sources scavenging picnics and camp sites, where it competes with the Grey jay. Steller's jays will visit feeders and prefer black-oil sunflower seeds, white striped sunflower seeds, cracked corn, shelled raw peanuts, are attracted to whole raw peanuts. Suet is consumed but in the winter season; the nest is in a conifer but is sometimes built in a hollow in a tree.
Similar in construction to the blue jay's nest, it tends to be a bit larger, using a number of natural materials or scavenged trash mixed with mud. Between two and six eggs are laid during breeding season; the eggs are oval in shape with a somewhat glossy surface. The background colour of the egg shell tends to be pale variations of greenish-blue with brown- or olive-coloured speckles; the clutch is incubated by the female for about 16 days. The male feeds the female during this time. Though they are known to be loud, during nesting they are quiet. Like other jays, the Steller's jay has variable vocalizations. One common call is a harsh SHACK-Sheck-sheck-sheck-sheck-sheck series. Call sounds exactly like an old-fashioned pump handle, its alarm call is a nasal wah. Some calls are sex-specific: females produce a rattling sound, while males make a high-pitched gleep gleep; the Steller's jay is a noted mimic: It can imitate the vocalizations of many species of birds, other animals, sounds of non-animal origin.
It will imitate the calls from birds of prey such as the red-tailed hawk, red-shouldered hawk, osprey, causing other birds to seek cover and flee feeding areas. The Steller's jay is the provincial bird of British Columbia. Goodwin, D.. Crows of the World. Seattle, WA: University of Washington Press. Greene, E.. R.. "Steller's jay - Cyanocitta stelleri". The Birds
The rough-skinned newt or roughskin newt is a North American newt known for the strong toxin exuded from its skin. A stocky newt with rounded snout, it ranges from light brown to olive or brownish-black on top, with the underside, including the head and tail, a contrasting orange to yellow; the skin is granular. They measure 6 to 9 cm in snout-to-vent length, 11 to 18 cm overall, they are similar to the California newt but differ in having smaller eyes, yellow irises, V-shaped tooth patterns, uniformly dark eyelids. Males can be distinguished from females during breeding season by large swollen vent lobes and cornified toe pads. Habitats of rough-skinned newts are found throughout the West Coast of the United States and British Columbia, their range extends south to Santa Cruz and north to Alaska. They are uncommon east of the Cascade Mountains, though are found as far as Montana. One isolated population lives in several ponds just north of Moscow and was most introduced. A number of subspecies have been defined based on local variants, but only two subspecies have wider recognition: Taricha granulosa granulosa – rough-skinned newt Taricha granulosa mazamae – Crater Lake newt It is now believed that the Taricha granulosa mazamae subspecies is no longer valid, as specimens that look similar to T.g.m have been found in areas of Alaska as well Many newts produce toxins from skin glands as a defense against predation, but the toxins of the genus Taricha are potent.
An acrid smell radiates from the newt. Toxicity is experienced only if the newt is ingested, although some individuals have been reported to experience skin irritation after dermal contact if the eyes are touched after handling the animal without washing hands. In 1979 a person died after ingesting a newt; the newt produces a neurotoxin called tetrodotoxin, which in this species was called "tarichatoxin". It is a number of other marine animals; this toxin targets voltage gated sodium channels via binding to distinct but allosterically coupled sites. Because TTX is much larger than a sodium ion, it acts like a cork in a bottle and prevents the flow of sodium; the reverse binding to sodium channels in nerve cells blocks electrical signals necessary for conducting nerve impulses. This inhibition of firing action potentials has the effect of inducing paralysis and death by asphyxiation. Throughout much of the newt’s range, the common garter snake has been observed to exhibit resistance to the tetrodotoxin produced in the newt's skin.
While in principle the toxin binds to a tube-shaped protein that acts as a sodium channel in the snake's nerve cells, researchers have identified a genetic disposition in several snake populations where the protein is configured in such a way as to hamper or prevent binding of the toxin. In each of these populations, the snakes exhibit resistance to the toxin and prey upon the newts. Successful predation of the rough-skinned newt by the common garter snake is made possible by the ability of individuals in a common garter snake population to gauge whether the newt's level of toxin is too high to feed on. T. sirtalis assays toxin levels of the rough-skinned newt and decides whether or not the levels are manageable by swallowing the newt, either swallowing or releasing the newt. Toxin-resistant garter snakes are the only known animals today that can eat a rough-skinned newt and survive. In evolutionary theory, the relationship between the rough-skinned newt and the common garter snake is considered an example of co-evolution.
The mutations in the snake’s genes that conferred resistance to the toxin have resulted in a selective pressure that favors newts which produce more potent levels of toxin. Increases in the amount of newt apply a selective pressure favoring snakes with mutations conferring greater resistance; this cycle of a predator and prey evolving to one another is sometimes termed an evolutionary arms race because the two species compete in developing adaptations and counter adaptations against each other. This has resulted in the newts producing levels of toxin far in excess of what is needed to kill any other conceivable predator; some newts secrete enough toxins to kill several adult humans. It appears that in some areas, the common garter snake has surpassed the newt in the evolutionary arms race by developing such a strong resistance to the toxin that the newt is unable to compete with its production of the toxin. There has been phylogenetic evidence that indicates elevated resistance to TTX has originated independently and only in certain species of garter snakes.
The resistance has evolved in at least two unrelated species in the genus Thamnophis and at least twice within T. sirtalis. The toxin, when injected into animals, may not kill resistant animals. In snakes, individuals who showed some resistance tended to move slower after TTX injection, while those with less resistance become paralyzed. Newts are not immune to their own toxin; the toxin in newts consists of a tradeoff. Each time they release the toxin, they inject themselves with a few milligrams; the TTX becomes concentrated in certain parts of the tissue after passing through cell membranes. As a result of tissue exposure to the toxin, newts have evolved a protection mechanism via a single amino acid substitution to the voltage-gated sodium channel affected by TTX. Puffer fishes show a similar amino acid