Chihuahuan Raven Life History

Habitat

Habitat Scrub

Chihuahuan Ravens inhabit very dry areas in which Common Ravens and American Crows are less common or absent. They nest in grasslands and deserts with yucca and scattered small trees such as mesquite, acacia, shinnery oak, and creosote bush. Where nesting structures such as utility poles are present, they also nest in shortgrass prairie. At the edges of these habitats, Chihuahuan Ravens range into pinyon-juniper woodlands and into cottonwood-sycamore stream corridors, where they sometimes nest. After nesting, some individuals move into agricultural landscapes, landfills, and cattle lots, where food may be more plentiful, especially during winter.

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Food

Food Omnivore

Chihuahuan Ravens, like other members of the crow and jay family (collectively known as corvids), are omnivorous and opportunistic, eating hundreds of different foods. They forage by walking on the ground, flying low, or scanning from a perch. Their diet includes many types of insects, especially larger grasshoppers and beetles, as well as stinkbugs, treehoppers, and oakworms, which they glean from bark. They overturn dried cow manure to eat cutworms living in them. They also consume spiders. Chihuahuan Ravens eat many sorts of vertebrates, including fish, amphibians, reptiles, birds, and mammals. They sometimes capture live lizards (including horned-toads), birds, and rodents, which they seize with the bill and consume quickly; however, most of their animal diet consists of roadkill, especially cottontails and jackrabbits. During spring and early summer, they take eggs and nestlings of many species of birds, ranging from the small Horned Lark to large predators like Harris’s Hawk. Chihuahuan Ravens also consume ample plant matter. Among grains, they eat sorghum, corn, milo, wheat, barley, oats, and rye, along with other cultivated crops like sunflower, pecan, melon, and peanut. Native plant foods include fruits of prickly pear, buckthorn, and hackberry, plus seeds of many plants. They also readily eat food scraps at landfills and campgrounds. Where food is plentiful, Chihuahuan Ravens store (cache) excess food for later.

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Nesting

Nest Placement

Nest Tree

The nest is set on a prominent feature such as a cliff, tree, utility pole, windmill, or oil derrick.

Nest Description

The female builds a large, bulky nest mostly of mesquite twigs and branches and lined with softer material such as yucca fiber, tree bark, hair, burlap, cotton, feathers, grass, paper, rags, rope, twine, or wool. Nests measure roughly 18 inches across and 13 inches tall, with interior cup 7 inches across and 5.5 inches deep. Pairs frequently reuse and enlarge nests over several breeding seasons.

Nesting Facts
Clutch Size:1-8 eggs
Egg Description:Green to blue with blotches and streaks of brown.
Condition at Hatching:Helpless with tufts of down.
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Behavior

Behavior Ground Forager

Chihuahuan Ravens begin nesting in spring. Courtship between male and female involves mutual preening, bill contact, exposing the white neck feathers, and head-bobbing. Pairs often execute elaborate flight maneuvers together, including barrel rolls, which may be part of courtship or pair bonding. Although they usually nest no closer than a half-mile to others of their species, neighboring pairs gather to mob potential predators that approach a nest too closely. Pairs do defend a territory when nesting, but they typically tolerate the presence of neighbors in the territory. Even during the nesting season, these ravens sometimes gather in flocks where food and water are plentiful. In flocks, some individuals are dominant over others. In situations of conflict, dominant birds crouch and call, displaying the white neck feathers and ruffling the throat feathers.

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Conservation

Conservation Low Concern

According to the North American Breeding Bird Survey, Chihuahuan Raven populations were stable between 1968 and 2015. Partners in Flight estimates a global breeding population of 840,000 and rates the species a 9 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. Because Chihuahuan Ravens consume some agricultural crops, humans have persecuted them by trapping, poisoning, and shooting, but this is less common today than in the past. Many ravens die by electrocution, associated with their use of utility poles for nesting (and gathering wire for nesting material). Some studies indicate that agricultural chemicals such as herbicides have reduced nesting success.

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Credits

Dwyer, James F., James C. Bednarz and Ralph J. Raitt. (2013). Chihuahuan Raven (Corvus cryptoleucus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2015.2. Patuxent Wildlife Research Center, Bird Banding Laboratory 2015.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2017). The North American Breeding Bird Survey, Results and Analysis 1966–2015. Version 2.07.2017. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, USA.

Sparks, R. A., D. J. Hanni and M. McLachlan. (2005). Section-based monitoring of breeding birds within the Shortgrass Prairie Bird Conservation Region (BCR 18). Rocky Mountain Bird Observatory, Brighton, Colorado, USA.

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