Photo: U.S. Fish & Wildlife Service
There were eight of them. Large black birds wheeling, sailing, diving, soaring and rolling against the strong breeze, looking as though they were having the time of their lives. Then they disappeared over the hill.
I see them and hear them often on our morning walks, sometimes very close and at other times sailing over that big hill at the end of our little valley. Ravens truly are amazing birds with endless legends, myths, history and stories as well as facts about them. Google “bird raven” and you get 23,700,000 hits.
The common raven (Corus corax), also known as the Northern raven, is the largest perching bird and the most widely distributed of all corvids (crows, jays and magpies). It is an intelligent bird – a bird with a sense of humor that plays tricks, a bird found throughout the northern hemisphere from arctic to temperate zones, including deserts, and islands in the Pacific Ocean, and up to 20,000 feet on Mount Everest. Everyone at Placerita Canyon knows the raven for its giant nests in the picnic area and its frequent presence.
Ravens average 25 inches in length and weigh a little over 2.5 pounds. Some remarkable feats of problem-solving have been observed in the species, leading to the belief that the birds are highly intelligent. Over the centuries, the raven has been the subject of mythology, folklore, art and literature. “Tell me what thy lordly name is on the Night’s Plutonian shore! Quoth the raven, `Nevermore.’”
In many indigenous cultures, including those of Scandinavia, ancient Ireland and Wales, Bhutan, the northwest coast of North America, Siberia and northeast Asia, the common raven has been revered as a spiritual figure or god.
It has coexisted with humans for thousands of years and in some areas has been so numerous that it is considered a pest. Part of its success comes from its omnivorous diet; common ravens are extremely versatile and opportunistic in finding sources of nutrition, feeding on carrion, insects, cereal grains, berries, fruit, small animals and food waste.
In recent years, biologists have recognized that birds engage in play. Juvenile common ravens are among the most playful of bird species. They have been observed to slide down snowbanks, apparently purely for fun. They even engage in games with other species, such as playing catch-me-if-you-can with wolves and dogs.
Common ravens are known for spectacular aerobatic displays, such as flying in loops or interlocking talons with each other in flight. They are also one of only a few species that make their own toys. They have been observed breaking off twigs to play with socially.
Common ravens have been observed to manipulate others into doing work for them, such as by calling wolves and coyotes to the site of dead animals. The canines open the carcass, making it more accessible to the birds. They watch where other common ravens bury their food and remember the locations of each other’s food caches so they can steal from them. This type of theft occurs so regularly that common ravens will fly extra distances from a food source to find better hiding places for food. They have also been observed pretending to make a cache without actually depositing the food, presumably to confuse onlookers.
Common ravens are known to steal and cache shiny objects such as pebbles, pieces of metal and golf balls. One theory is that they hoard shiny objects to impress other ravens. Other research indicates that juveniles are deeply curious about all new things, and that common ravens retain an attraction to bright, round objects based on their similarity to bird eggs. Mature birds lose this intense interest in the unusual.
Juveniles begin to court at an early age but may not bond for another two or three years. Aerial acrobatics, demonstrations of intelligence and an ability to provide food are key behaviors of courting. Once paired, they tend to nest together for life, usually in the same location. Instances of non-monogamy have been observed in common ravens, by males visiting a female’s nest when her mate is away.
Breeding pairs must have a territory of their own before they begin nest-building and reproduction, and thus aggressively defend a territory and its food resources. Nesting territories vary in size according to the density of food resources in the area.
The nest is a deep bowl made of large sticks and twigs, bound with an inner layer of roots, mud and bark and lined with a softer material. The nest is usually placed in a large tree or on a cliff ledge, or less frequently in old buildings or utility poles.
Females lay three to seven pale bluish-green, brown-blotched eggs. Incubation is about 18 to 21 days, by the female only. However, the male may stand or crouch over the young, sheltering but not actually brooding them. Young fledge at 35 to 42 days and are fed by both parents. They stay with their parents for another six months after fledging.
Like other corvids, ravens can mimic sounds from their environment, including human speech. They have a wide range of vocalizations. Fifteen to 30 categories of vocalization have been recorded for this species, most of which are used for social interaction. Calls recorded include alarm calls, chase calls and flight calls.
Non-vocal sounds produced by the common raven include wing whistles and bill snapping. Clapping or clicking has been observed more often in females than in males. If a member of a pair is lost, its mate reproduces the calls of its lost partner to encourage its return.
This article originally appeared in the May-June 2012 edition of The Rattler, the newsletter of the Placerita Canyon Nature Center Associates. The Nature Center is located at 19152 Placerita Canyon Road, Newhall. For information or to volunteer, visit www.Placerita.org. Join the PCNCA Facebook group here: http://www.facebook.com/groups/pcnca.