By Jon Friedman
(This is an updated and expanded version of a raven article originally published in our May/June, 1996 issue of The Wild Bird Store Newsletter)
Ravens belong to the Corvidae family of birds which includes all North American jays (except one) and the Yellow-billed and Black-billed Magpies. The subfamily of Corvinae includes the Common Raven, Chihuahuan Raven (formerly called the White-necked Raven), Common Crow, Northwestern Crow, Fish Crow, Mexican Crow, Hawaiian Crow, Piñon Jay and the Clark’s Nutcracker. Many of the Corvidae family of birds are considered to be among the most intelligent of all avian species, along with many parrots and certain others. It has been well documented that many ravens have discovered how to make simple tools and use them to their advantage in foraging. For example, in order to reach foodstuffs that are beyond normal reach, as in cracks or crevices in trees or rocks, ravens have been observed snipping a twig to the correct length and, while holding it in their bills, using the twig to excavate or pry the food out. They have even been observed customizing the tool to fit particular spaces.
Photo by C. Friedman
They also have the ability to learn, as well as mimic, a large vocabulary of human and non-human sounds. In many cultures, they have been and are kept as pet birds. Ravens have uncanny intelligence – a trait they share with all members of the crow family. They seem able to learn new behaviors even from other kinds of animals. In the American Southwest, they have developed a knack for killing snakes – far from typical raven behavior – by watching desert roadrunners hunting snake prey.
Throughout history, there has been a shared relationship between humans and ravens. Many cultures have attributed spiritual, magical, or godly powers to these birds. Ravens have been described as God’s messengers. Noah sent out a raven to test the floodwaters. The ancient Norse god Odin relied on ravens perched on his shoulders to serve as his eyes and ears. Elsewhere, ravens are messengers of another sort. A medieval Irish treatise on magic lists more than two dozen prophecies that are based on raven behavior. Most schoolchildren are familiar with Edgar Allan Poe’s famous poem, The Raven. In the Pacific Northwest and adjacent Canada, the indigenous tribes recognized its magical and divine powers.
Distinguishing ravens from crows, particularly by non-birders, is sometimes difficult as they are often mistaken for each other. However, in Southern Arizona, where crows are seldom seen, this is rarely a challenge presented to birders. Several easily observed features help distinguish the species. Ravens are the largest of all songbirds and clearly larger than crows. Crows are
generally 17-21” long while the Common Raven measures 22-27” long. Chihuahuan Ravens may be harder to distinguish by size alone as their average size of 19-21” puts them between large crows and small Common Ravens. Crows and ravens appear solidly black in color but in direct sunlight may have a purplish or metallic sheen to them. Males and females are similar in appearance and even the juveniles greatly resemble the adults.
Photo by C. Friedman
The wingspan of the Common Raven measures approximately four feet, the largest by far of the Corvidae. It also has a larger, arched bill and fan-shaped tail. Crows have slender, straighter bills and fan-shaped tails. In flight, the ravens are more hawk-like, alternating flapping and sailing with flat wings. Unlike crows, the ravens can soar at high altitudes and ride thermals in an upward spiral, much like hawks, vultures, and eagles. Crows fly along with steady and shallow wingbeats and are more often seen in larger flocks.
In appearance, crows are not only smaller and more compact, but seem more streamlined. Ravens have a more shaggy appearance, particularly in the throat feathers, especially when calling. Even in silhouette, these shaggy feathers will usually be apparent. The Chihuahuan Raven is further recognized by the white feather bases on the neck and upper breast. However, this distinguishing feature is often hard to see. This species used to be called the “White-necked Raven.” Other characteristics to look for are the fact that crows generally take flight by jumping directly into the air while ravens normally hop about on the ground several times prior to take off. The Common Raven, in flight, is incredibly aerobatic, rolling and tumbling in mid-air, often seen in mated pairs.
Identifying the two different ravens is more challenging than distinguishing ravens from crows. The Chihuahuan Raven produces a higher pitched, flatter “kraak” or “cr-r-ruck” vocalization. The Common Raven, possessing a somewhat lower-pitched, more drawn-out croak, has a far more widespread range in the United States. It can be found in all the western states, along the northern tier states, and across the southern regions of Canada’s provinces. The Chihuahuan Raven, found only in the American Southwest, has a more limited range. Its northern range limit is the southern regions of Arizona, New Mexico and Texas. This species may withdraw from the northern parts of its winter range in the coldest weather. It is more abundant throughout much of Northern Mexico.
Where their ranges overlap in the southwest, it is difficult to identify them by sight alone, but the combination of size, vocalizations and habitat preference provides useful aids. The Common Raven is not only more widespread in its range but also more liberal in choosing habitat. It has adapted to many varying environments from the coastal shores, to plains, to mountains and forests, and can be seen at most landfills – where it may be the most numerous and common bird present. The Chihuahuan Raven prefers grasslands and desert habitat. In Southern Arizona, many birders will tell you that the raven you see in winter months is most likely the Common Raven while the Chihuahuan Raven is the more common summer resident where its range occupies the lower yucca-mesquite-grassland habitats.
Photo by C. Friedman
The Common Raven tends to occupy the higher elevations, often nesting on preferred cliffs or above the timberline. Nests are constructed of tree branches and sticks most often broken off the trees by the birds and not gathered from the ground. Nests are often quite wide and deep, three to five feet in diameter and one to two feet deep. The sticks and branches are usually about three feet long and about one inch in diameter. The foundation of the nest consists of the largest branches, along with clumps of earth and grass. Thinner twigs make up the rim of the nest. The interior cup is lined with bark shreds and any hair, wool, fur or similar fibers the birds can locate. Nests typically take about two and a half weeks to build. They also build nests on tall trees and power poles.
Both species are monogamous, mate for life, build the nest together, lay 3-7 eggs, take turns incubating the slightly greenish eggs with brown spots or blotches, and share the parenting responsibilities equally. They are excellent parents, completely devoted to raising and protecting their young and continuing to feed and look after them long after they are fledged. Nest sites are used year after year in most cases. Their population density seems to be greatest in Southern Arizona in the Sulphur Springs Valley from north of Willcox to the Mexican border, from the Huachuca Mountains east to the southeastern corner of the state. Nesting sites in higher elevations, tall trees and cliffs would indicate the Common Raven while lower elevation nests in shorter desert plants and trees would more reliably be the Chihuahuan Raven. However, there may be considerable overlap where their habitats and/or ranges abut.
Ravens are omnivorous and tend to take advantage of any food opportunity. Their diets are determined by the circumstances they encounter. Both species are opportunistic and feed on both fresh and scavenged foods. In the Arctic, they team up to kill young seals on ice floes, delivering strong blows with their beaks. Their diets include a wide variety of dead animals that they scavenge. Typically, this would include elk, deer, whales, seals and fishes. In these instances, they will usually be competing with gulls and vultures for the remains of kill by bears, wolves, coyotes, etc. They also eat frogs, tadpoles, worms, crabs, shellfish (which they drop aloft onto the ground or rocks to open), fishes, eggs and nestlings, songbirds and herons. They have been seen following the plow for insects, mice and other rodents. They also forage for berries and fruits and sometimes are common visitors at campgrounds and picnic areas scavenging for leftovers from humans. They also scour the highways looking for roadkill. On a recent birding trip, we saw four Common Ravens feeding on a dead kit fox in the road near Silver City, New Mexico. Additionally, The Chihuahuan Ravens are known for eating common desert dwellers such as lizards, snakes, spiders, beetles and other insects, cactus fruits and crops such as melons, grains, corn and peanuts. In addition, scientists have observed that the Chihuahuan Raven has discovered how to get nectar from desert flowers by imitating the feeding habits of nectar-eating bats!
Ravens, like other corvids, also stash (or cache) foods – particularly in northern areas during colder winter months. They also accumulate a wide variety of other non-food items as well. They have found and stashed such items as shiny jewelry, Styrofoam cups, food wrappers, metal foil, fishing lures, plant markers, items of human clothing, pieces of animal fur and bones, and many types of items commonly found in landfills. Ornithologists seem somewhat puzzled by these non-food items which ravens commonly cache, as it seems to serve no useful purpose and wastes precious energy. However, the birds have been seen interacting with these types of objects in what can only be described as “playful activity.” After all, if these birds are very intelligent, make resourceful use of their time, cache food when natural resources are at a low or depleted – why not have some fun time and “toys” to enjoy and engage with? I guess birds deserve to enjoy their leisure time, too!