Geococcyx californianus

Geographic Range

Greater roadrunners are primarily a species of the southwestern United States, but their full range includes other areas as well. They occur in California, Arizona, Nevada, Utah, Colorado, Texas, New Mexico, Kansas, Oklahoma, Louisiana, and Arkansas. Their range continues into southern Mexico, where their closest relative the lesser roadrunner ( Geococcyx velox ) becomes the dominant species.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

This species prefers arid deserts and other regions with a mix of scattered brush for cover and open grassy areas for foraging. For breeding, they require coastal sage scrub or chaparral habitat. In the outer limits of their range they may be found in grasslands and at the edges of woodlands.

• Habitat Regions
• terrestrial terrestrial

• Terrestrial Biomes
• desert or dune desert or dune
• chaparral chaparral
• scrub forest scrub forest

Physical Description

The head, neck, back, and wings of greater roadrunners are dark brown-black and heavily streaked with white, while the breast is mostly white. The eyes are bright yellow and there is a postocular streak of bare blue and red skin. A particularly notable feature is the crest of black feathers, which is raised or lowered at will. Overall, the body has a streamlined appearance, with a long tail that may be carried at an upward angle. The legs and beak are blue. The feet are zygodactylous, with two toes pointed forward and two toes pointed backward. The sexes are similar in appearance. Immature greater roadrunners lack the colorful postocular streaks and are more bronze in color.

Greater roadrunners are medium-sized birds, weighing 227 to 341 g. An adult’s length is between 50 and 62 cm and the height is between 25 and 30 cm. Greater roadrunners have a wingspan of 43 to 61 cm.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

Reproduction

Courtship behavior involves the male’s foot pursuit of the female, with frequent rests. Food is an important component of the mating ritual. The male will tempt the female with a morsel such as a lizard or snake dangling from its beak. If the female accepts the offered food, the pair will probably mate. In another display, the male wags his tail in front of the female while bowing and making a whirring or cooing sound; he then jumps into the air and onto his mate. Greater roadrunner pairs may mate for life.

• Mating System
• monogamous monogamous

The breeding and nesting seasons vary geographically. In regions where there is one rainy season they nest only in the spring. Where there are two rainy seasons and thus more food resources, they will nest again in August and September. Brood size ranges from 2 to 8 eggs, which are white or pale yellow. Incubation lasts about 20 days and begins after the first few eggs are laid. Hatching is therefore asynchronous. Young are altricial and their development is quite rapid; they can run and catch their own prey at 3 weeks. Sexual maturity is reached at 2 to 3 years of age.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
• oviparous oviparous

Both parents help build the nest; while the male collects the materials, the female does most of the construction. The nest site is almost always a few feet above the ground in a bush, cactus, or low tree. It is made with sticks, grass, feathers, and sometimes snakeskin or cow manure. Both parents incubate the eggs and feed the chicks once they hatch. Although the young leave the nest within 18 to 21 days, the parents continue to feed them for up to 30 to 40 days.

Greater roadrunners occasionally engage in brood parasitism. For example, roadrunner eggs have been observed in the nests of the common raven and the northern mockingbird .

• Parental Investment
• altricial altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • protecting
    • male
    • female
• pre-weaning/fledging
  • provisioning
    • male
    • female
  • protecting
    • male
    • female
• pre-independence
  • provisioning
    • male
    • female
  • protecting
    • male
    • female

Lifespan/Longevity

The lifespan of G. californianus is 7 to 8 years. Factors that may limit their survival include predation by hawks , house cats , skunks , coyotes , or raccoons . Further, since greater roadrunners are a nonmigratory species, they may succumb to icy weather in a particularly cold year.

Behavior

Greater roadrunners are non-migratory and pairs defend their territories year-round. These birds can run up to 17 miles an hour. In fact, they prefer to walk or run and will fly only when absolutely necessary. Even then, they can only remain airborne for a few seconds. The long tail is used for steering, braking, and balancing. They are also known for their curiosity; they won't hesitate to approach humans. Greater roadrunners have also been observed "sunbathing." In the morning and on cooler days, they position their scapular feathers so the black skin on the dorsal apteria can absorb the sunlight and warm the body. Conversely, they must also cope with the scorching heat of the southwest. One way they do so is by reducing their activity by 50% in the heat of midday. Other desert adaptations include entering hypothermia at night to conserve energy, water conservation when water is scarce, and a salt-secreting nasal gland.

• Key Behaviors
• cursorial
• flies
• diurnal diurnal
• motile motile
• sedentary sedentary
• territorial territorial

Communication and Perception

Greater roadrunners have a wide range of vocalizations. The song of G. californianus is a series of six slow, low coos in descending pitch. During the mating season males will also attract females with a whirring call. The alarm call is a clackety noise produced by clicking the mandibles together in a sharp and rapid manner. The chicks give a buzzing begging call.

• Communication Channels
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

The diet of G. californianus is omnivorous and varied, a good strategy for survival in the typically harsh environments of the southwest. They eat large insects , scorpions , tarantulas , centipedes , lizards , snakes , and mice . They have even been known to eat rattlesnakes , although this is rare. Greater roadrunners are potential predators of quail , adult sparrows , hummingbirds such as Anna's hummingbird , and the golden-cheeked warbler . Feeding on netted birds has also been reported. They feed on prickly pear cactus where available. When hunting they walk rapidly, scanning for prey, and then dash forward to make the catch. They may also jump into the air to catch passing insects. To kill small creatures such as rodents , greater roadrunners smash the prey's body and head against a rock and then swallow it whole. Often part of the animal is left hanging out of the mouth while it is being digested.

• Primary Diet
• omnivore omnivore

• Animal Foods
• birds
• mammals
• reptiles
• eggs
• insects
• terrestrial non-insect arthropods

• Plant Foods
• wood, bark, or stems

Predation

Hawks , house cats , skunks , coyotes , and raccoons prey upon greater roadrunners. Coyotes also eat their eggs. This species relies largely on its swiftness to outrun predators. It also uses patches of brush for hiding, and it places its nest above ground to deter predation on the eggs.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Geococcyx californianus plays both predator and prey roles. It eats, and therefore potentially reduces the populations of, many small vertebrates such as lizards, mice, and other birds. It also consumes insects and other invertebrates. Greater roadrunners provide food for predators such as coyotes, hawks, skunks, and raccoons.

Economic Importance for Humans: Positive

Greater roadrunners help eliminate pests such as mice and various insects. Humans are frequently captivated by the odd behavior of the species.

• Positive Impacts
• ecotourism ecotourism
• controls pest population

Economic Importance for Humans: Negative

There are no known adverse affects of Geococcyx californianus on humans.

Conservation Status

Habitat loss and urban sprawl are the major threats to greater roadrunners. The construction of roads causes fragmentation of habitat as well as mortality from cars. Greater roadrunners are also illegally shot in response to predation on quail. Further, agricultural pesticides can adversely affect the species if bioaccumulated through their prey.

Research shows that Geococcyx californianus has little chance of persisting in coastal southern California, where sage scrub areas occur only in highly populated areas. Development has reduced this potential habitat to patches too small for greater roadrunners’ large territorial requirement.

Other Comments

Recently, a right femur from the greater roadrunner’s ancestor, Geococcyx californianus conklingi , was discovered in southeastern Arizona. This subspecies is larger than the present-day form of the greater roadrunner, Geococcyx californianus californianus . Modern roadrunner fossils have been found in California, New Mexico, and Chihuahua, Mexico.

Additional Links

Encyclopedia of Life

Contributors

Allison Poor (editor), University of Michigan-Ann Arbor.

Elizabeth Grisham (author), Michigan State University, Pamela Rasmussen (editor, instructor), Michigan State University.

References

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