California towhees (Pipilo crissalis) are found in coastal western North America from southern Oregon to the southern tip of Baja California. However, they are absent in most of central Baja California and some eastern counties in California. California towhees are native to semiarid uplands and moist riparian habitats. They are permanent residents throughout their range. Therefore, they are not found anywhere outside the range described above. The upper and lower Sonoran zones of California have a high relative abundance of California towhees. (Byers, et al., 1995; Haight and Benedict, 2020)
California towhees occupy most of coastal California. They are particularly abundant in San Diego County, except for the Coronado Peninsula. Though they can be found within urban areas, they are absent in highly populated cities. Ecosystems where California towhees are highly abundant include chaparral, riparian, scrub, and high-desert scrub areas. They can also be found in the undergrowth of riparian and oak woodlands. They are more abundant in coastal lowlands rather than higher elevations. Essentially, California towhees inhabit any ecosystem where native scrub plant species are found. This includes long-developed parts of San Diego that contain small amounts of native scrub. Even though they are not common in forested areas of high mountains, they were still found in every foothill and mountain square, excluding Palomar Mountain, Hot Springs Mountain, Cuyamaca Peak and Mount Laguna.
California towhees are widespread in sparse, desert-edge scrub habitats. However, they are low in abundance or not present in creosote bush scrub on desert floors. Even though mesquite thickets provide a good habitat for them in canyon ecosystems, California towhees are absent in the Mesquite Bosque of Borrego Valley. A few records have provided information on locations for winter dispersal of California towhees. These locations include Borrego Springs, Carrizo Valley, and Salton Sink. (Unitt, 2004)
California towhees are around 21 to 25 cm in length. Their heads and upper bodies are brown with a greyish tinge. The lower parts of their throats have a distinct gorget of dark streaks, while the rest of their under parts are pale grey with a whiter shade on their bellies. Juvenile California towhees lack the gorget of streaks along their throat. The most distinguishing feature of California towhees is their contrasting rich cinnamon-buff vent and undertail coverts. Their tails are long and rounded with brown coloration. Their wings are dark grey to brown with narrow grey-buff feather edges. Their bills are black, but their lower mandibles have a paler tone. This description can be applied to both males and females as there is little sexual dimorphism within California towhees. Measurements of wings, tails, and bills are different for males and females of this species. For females the measurements are 7.9 to 9.8 cm, 8.1 to 11.1 cm, and 1.4 to 1.6 cm, respectively. For males the measurements are 8.6 to 10.3 cm, 9.3 to 11.3 cm, and 1.3 to 1.6 cm, respectively. (Byers, et al., 1995)
California towhees form long-term pair bonds and are also socially monogamous. Studies suggest that paired California towhees stay bonded for at least five years. However, the sex ratio is slightly biased towards males. During breeding season, females approach a male while fluttering their wings and raising their tails, indicating that they are ready for copulation. Females also indicate their reproductive status using high-pitched vocal sounds and by approaching males while holding onto nesting material with their bills.
Male California towhees establish territories during the spring, from which they sing in order to attract females. Once a female locates a potential mate, pair formation takes place rapidly. During the first days of partnership California towhees express high rates of vocal duets. These take place several times a day as a mechanism to reaffirm the attachment between the two members. Other studies have suggested that these vocal duets also serve to coordinate behaviors shared within a pair such as territory defense as well as investment in offspring. Both sexes become aggressive towards individuals that cross into their territory. If a territory is left undefended it will be shared with neighboring pairs throughout the year. (Benedict, 2008; Benedict, 2009; Haight and Benedict, 2020)
California towhees nest in specific sites, which are selected by either the male or female of a pair. Suitable nest sites include trees, saplings, vines, and shrubs. California towhees sometimes select artificial structures as nesting sites. They typically build their nests at a moderate to low height above the ground. They rarely nest on the ground. While nesting behavior is not well known for California towhees, studies on closely related canyon towhees (Pipilo fuscus) have shown that females build nests while males observe the process from a distance. Some of the materials used for constructing nests include twigs, grasses (alive or dead), dry plant stems, dry flowers, plastic ribbons, and sagebrush bark strips. Nests have outside diameters between 17.6 and 22.3 cm and are 3.1 to 3.6 cm deep. Studies have indicated that nests in riparian habitats are thicker and shallower than nests in upland habitats. This is because nests in riparian habitats require more insulation from the cooler climate compared to upland habitats. Upland nests are more exposed to the sun and therefore require thinner and deeper nests to dissipate heat.
The eggs laid by California towhees range in shape from sub-elliptical to long sub-elliptical, with a average size of 23.9 mm long and 18.1 mm wide. Eggs are pale bluish-white or creamy white with a smooth, slightly glossy texture. Some studies indicate that clutch sizes are between two to five eggs, while others indicate that they range between three and four. The egg-laying period takes place several days after nests are built. Females lay one egg per day until they have a complete clutch. The incubation period begins after females lay their penultimate eggs, and lasts 11 to 14 days after.
Young birds are born in an altricial condition. They are only able to hold their head up, open their mouths, and make slight vocalizations. Hatchlings begin to develop feathers within six and eight days. They reach their full weight within 4 to 6 weeks. Within 6 to 8 days old, most chicks are able to leave their nests. However, they are unable to fly during this stage. At 3 to 4 weeks old they are able to forage for themselves. (Haight and Benedict, 2020)
Both male and female California towhees are involved in parental care. Female brood the young, while both adults feed and protect them. Brooding or shading the young is performed depending on changes in the ambient temperature. Studies have indicated that, while in their altricial condition, chicks are mostly fed a variety of insects. However, as chicks begin to fledge their diet becomes more omnivorous and similar to that of adults. Nevertheless, they are still fed by their parents at this stage. During the period in which young birds reside in nests, their parents ensure that nests are clean, which includes removing the fecal sacs produced by chicks. (Haight and Benedict, 2020)
According to data from the USGS, the maximum recorded age of an individual California towhee was 12 years and 10 months. A study conducted by the Hastings Natural History Reservation involving the survivorship of 432 banded individuals of this species resulted in fewer than 5 individuals surviving until 7 years old; none in this study survived to 8 years old. Some of the causes of mortality in this species include frequent encounters with automobiles. This is because California towhees are attracted to roadside vegetation and they fly relatively slow. Additionally, several species of biting lice are known to infect this species and cause diseases. (Haight and Benedict, 2020)
California towhees are known to hop or run when foraging within small distances. However, due to their short, broad wings and long tail, their flight pattern looks somewhat uncoordinated. When landing, they usually spread their wings and tails to coast. California towhees are highly territorial. They defend territories in which they forage, court mates, copulate, and nest. This is done by males and females of the species and can lead to physical conflicts with nearby pairs.
A typical aggressive display involves standing in front of a rival with head lowered and tail raised, followed by opening one or both wings, and moving them back and forth in a fluttering motion. This behavior is performed while moving in circles. Another type of display involves picking up small sticks from the ground and holding them in front of the opponent as a threat. If these techniques are ineffective in driving trespassers away, California towhees proceed to attack opponents by leaping into the air and striking them with feet and bill.
Studies suggest that there is some degree of interspecific territoriality within this species, as it has been observed chasing other birds away from their nests. However, they have been seen chasing and being chased by other species from one tree to another for long periods. Other studies have shown California towhees feeding alongside other species from the same source without any conflict.
California towhees are member of the order of the songbirds (Passeriformes). This order is characterized by their ability to produce complex vocal sounds. These include male songs, call notes, and combat notes. Male songs are composed of a repetition and elaboration of basic metallic sounds, starting with 3 or 4 notes at short intervals and ending in trill-like or accelerated series of call notes. These calls are used for attracting mates and establishing territories.
Call notes are shorter and are used for a variety of reasons including indicating start and end of daily activity, protest, and warning of predators. Combat notes are characterized by the rapid succession of guttural syllables and are used by California towhees when fighting each other. Studies have indicated that they are one of they earliest-rising birds in California. Vocalizations during breeding season take place in locations like tree tops, bushes, combs of roofs, peaks of high houses, utility poles, and during flight. California towhees are non-migratory, but individuals in California breeding upslope in chaparral exhibited post-breeding movement into lower mountain slopes. In addition, individuals established in higher elevations may move to lower elevations during the winter. (Haight and Benedict, 2020)
No exact home range for California towhees is reported, but they are extremely territorial around their nesting and foraging sites.
California towhees mainly use vocalization to communicate. During development, nestlings produce a series of hunger notes to notify the parents that they need food. This is only type of communication present in nestlings within this species. As adults they develop a variety of songs and calls, each different in pitch, amount of notes, and other elements.
Male songs used to attract females and advertise territory is composed of repetitive and elaborate metallic sounds. They start with 3 to 4 notes at short intervals and ending in an accelerated series of call notes. Studies have indicated that unmated males spend 47% of their time singing, while mated males spend less than 1% of their time performing this activity. Call notes are mainly used for situations that do not pertain to sexual behavior, including start and end of daily activities and warning calls towards predators. These call notes are more basic in composition compared to male songs. California towhees exhibit different types of call notes with the most frequent and versatile one serving the functions described above. Another version of this call is used to cease the hunger notes of chicks. This version also serves as a warning note to notify mates and fledglings about incoming predators. The third version serves as a contact note between mated birds that are hidden in vegetation.
In addition to these call notes, California towhees produce a type of “towhee squawk” used as a distress call by both adults and young. They produce this stress call when they are handled by other species, or predators. Adults also use the towhee squawk as an intimidation call when involved in a fight with species like California scrub-jays. Different calls are produced when fighting other California towhees. These calls involve the rapid succession of guttural syllables. There is not enough evidence to support the connection between non-vocal sounds and a specific function. (Benedict and McEntee, 2009; Haight and Benedict, 2020)
California towhees are omnivorous, since they feed on plant materials as well as insects. More specifically, they are granivorous with a diet that consists mainly of seeds. These seeds come from different types of plants including pigweed, knotweed, bur-thistle, alfilaria, and wild legumes. In addition, California towhees feed on cultivated-wild grains including oats, barley, wheat, and wild oats. Occasionally, California towhees feed on wild fruits such as elderberries, coffeeberries, spiny redberries, poison oak, and acorns. They also eat cultivated fruits like plum, apricots, peaches, and grapes. Their diet of insects includes beetles (order Coleoptera), true bugs (order Hemiptera), grasshoppers (order Orthoptera), flies (order Diptera), and spiders (order Araneae).
Studies conducted on the percentage distribution of food items consumed by California towhees indicates that 51% of their diet consists of weed seeds, 28% of grains, 14% of insects, 4% of wild and cultivated fruits, and the remaining percentage on other unspecified plant materials. 86% of their diet consists of plant materials, while the other 14% is composed of animal food. However, as nestlings their diet consists mostly of insects. Some of the methods used by this species for foraging include pecking, and bilateral scratching to uncover food covered by leaf litter under trees and shrubs. This last mechanism consists of a forward hop while moving both feet forward, followed by a backwards movement of the feet to displace litter. When feeding off berries, they perch below berries and fly up to grab them. As they grab a berry they fold their wings and perform a twisting motion with their heads to detach it. Regarding water consumption, most of their water during the dry season is obtained through cattle and coffee berries. (Haight and Benedict, 2020)
California towhees have a wide variety of predators including mammals, reptiles, and other birds. These predators are mostly nest predators, which implies that they target eggs and nestlings. In California oak-pine woodlands, California scrub-jays (Aphelocoma californica) are the main nest predators of California towhees. Other avian nest predators include:
Mammal nest predators include a variety of rodents including:
Deer mice (Peromyscous leucopus), California ground squirrels (Otospermophilus beecheyi), and Merriam’s chipmunks (Tamias merriami).
Adult towhee predators include:
Red-tailed hawks (Buteo jamaicensis), Cooper's hawks (Accipiter cooperii), American kestrels (Falco sparverius), sharp-shinned hawks (Accipiter striatus), western screech owls (Megascops kennicottii), great horned owls (Bubo virginianus), northern pygmy owls (Glaucidium californicum), coyotes (Canis latrans), rattlesnakes (subfamily Crotalinae), gopher snakes (Pituophis catenifer), and American bullfrogs (Lithobates catesbeianus).
One of the ways California towhees escape terrestrial predators is by fleeing to medium-density woody vegetation. They also take cover when predatory birds fly above their territories. In addition, nestlings and adults use a “towhee squawk” when handled by predators, to call for assistance from nearby members, or to startle the predator. (Haight and Benedict, 2020; Purcell and Verner, 1999)
This species acts as prey for several species of mammals, reptiles, and birds. Most of these are nest predators with the California Scrub-Jay on the top of the list as the main nest predator (Benedict et al., 2020). Therefore, breeding of the California Towhee, is key in maintaining the food chain that is comprised of these species. In addition, the towhee acts as a host for brood parasitism carried by the Brown-headed Cowbird (Benedict et al., 2020). The towhee is known to be highly susceptible to the cowbird’s parasitism due to its lack of response towards the parasitic adult and, or, the young. (Haight and Benedict, 2020)
There are no known positive effects of California towhees on humans.
There are no known negative effects of California towhees on humans.
According to recent information published by the Cornell lab of Ornithology, the California towhee conservation status is of least concern. They are also considered to be of least concern on the IUCN Red List. Nevertheless, populations of this species are constantly threatened by human activity. One threat is the spreading of pesticides in farms that contain food sources. Also, increasing numbers of high-speed vehicles and paved roads has increased the mortality rate of California towhees due to encounters with moving vehicles. Habitat loss, however, does not seem to be a huge factor affecting the success of California towhees.
The U.S. Fish and Wildlife Service (USFWS) considered the Inyo California towhee (P. crissalis eremophilus) subspecies as threatened because of the destruction and degradation of riparian habitats. This presents an obstacle for the nesting of this subspecies. Measurements implemented by USFWS for maintaining a stable population of this subspecies include removal of cattle and horses, as well as removal of invasive plant species - particularly salt cedar - that degrade native riparian habitats. USFWS also protected natural springs and restricted water projects, rural development, mining, off road vehicle use, and other human activities. In addition, members of the agency are monitoring brown-headed cowbird populations and impacts on the nests of Inyo California towhees. Over the years these actions have improved the habitat and addressed many of the threats to the Inyo subspecies population, which resulted in a significant increase of population size. (Bolger, et al., 1997; Haight and Benedict, 2020; "Inyo California Towhee (Pipilo crissalis eremophilus)[= Inyo Brown Towhee (Pipilo fuscus eremophilus)]. 5-Year Review: Summary and Evaluation.", 2008; "Recovery Plan for the Inyo California Towhee (Pipilo crissalis eremophilus)", 1998)
California towhees have several scientific names from which they can be identified, the most common being Melozone crissalis, rather than Pipilo crissalis. Eight subspecies have been identified, each limited to specific locations along the species geographic range. Some of them include P. crissalis bullata and P. crissalis eremophila. These two subspecies are distributed from southwest Oregon to northern California and Argus mountains in Inyo County, respectively. Fossils of California towhees date as far back as the Pleistocene, from asphalt traps in LaBrea and Carpenteria along the coast of California. (Haight and Benedict, 2020)
Ricardo Cruz (author), California State University, San Marcos, Tracey Brown (editor), California State University, San Marcos, Galen Burrell (editor), Special Projects.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
uses sound to communicate
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.
uses smells or other chemicals to communicate
to jointly display, usually with sounds in a highly coordinated fashion, at the same time as one other individual of the same species, often a mate
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
parental care is carried out by females
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
parental care is carried out by males
Having one mate at a time.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
an animal that mainly eats all kinds of things, including plants and animals
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
places a food item in a special place to be eaten later. Also called "hoarding"
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
uses sight to communicate
U.S fish and Wildlife Service. Inyo California Towhee (Pipilo crissalis eremophilus)[= Inyo Brown Towhee (Pipilo fuscus eremophilus)]. 5-Year Review: Summary and Evaluation.. 24. Ventura, California: U.S Fish and Wildlife Service. 2008.
U.S Fish and Wildlife Service. Recovery Plan for the Inyo California Towhee (Pipilo crissalis eremophilus). Region 1. Portland, Oregon: U.S Fish and Wildlife Service. 1998.
Benedict, L. 2009. Long-term occupancy of home ranges and short-term changes in use of habitat by California Towhees (Pipilo crissalis). The Southwestern Naturalist, 54(3): 324-330.
Benedict, L. 2008. Unusually high levels of extrapair paternity in a dueting songbird with long-term pair bonds. Behavioral Ecology and Sociobiology, 62(6): 983-988.
Benedict, L., J. McEntee. 2009. Context, structural variability and distinctiveness of California towhee (Pipilo crissalis) vocal duets. Ethology, 115(1): 77-86.
Bolger, D., T. Scott, J. Rotenberry. 1997. Breeding bird abundance in an urbanizing landscape in coastal southern Caliofornia. Conservation Biology, 11(2): 406-421.
Byers, C., J. Curson, U. Olsonn. 1995. Sparrows and buntings: a guide to the sparrows and buntings of North America. Boston, MA: Houghton Mifflin.
Haight, L., L. Benedict. 2020. "California Towhee(Melozone crissalis)" (On-line). In Birds of the World. Accessed May 09, 2020 at https://birdsoftheworld.org/bow/species/caltow/cur/introduction.
Purcell, K., J. Verner. 1999. Nest predators of open and cavity nesting birds in oak woodlands. The Wilson Bulletin, 111(2): 251-256.
Unitt, P. 2004. San Diego County Bird Atlas. San Diego, CA: Proceedings of the San Diego Natural History Museum.