Birds use vocalizations and calls to communicate for different purposes. Many bird species have a repertoire of various calls that they use in different contexts. However, some birds are especially well known for their wide diversity of vocalizations. One such bird that has several distinct calls is the common raven (Corvus corax).
The common raven is a large, intelligent corvid found throughout much of the Northern Hemisphere. Measuring up to 69 cm long with a 1.5 m wingspan, the common raven is entirely black, including its thick bill and shaggy throat feathers. It is larger than the closely related American crow, with more of a wedge-shaped tail and longer, narrower wings. The raven’s deep, croaking “tok” or “kor” call is distinctive.
Ravens are adaptable birds found in a variety of habitats, from forests to deserts to tundra. They are omnivorous generalists, eating a wide variety of plant and animal matter including bugs, small mammals, eggs, nestlings, and carrion. Ravens are social birds that mate for life. They build large, cup-shaped nests in which they lay three to seven eggs that incubate for about three weeks. Young ravens stay with their parents for 5-7 months after fledging.
Common ravens have a wide repertoire of over 30 different calls. Their vocalizations are complex and have meaning to other ravens. Researchers have described raven calls in several categories:
- Contact calls – short calls like “tok” used to identify one another at a distance
- Alarm calls – harsh, rapid calls like “kraa” that recruit others to mob threats
- Food calls – excited yelps given when ravens discover food
- Non-vocal sounds – clicks and snaps of the bill during displays
- Song – long sequences of gurgling sounds given at nest and roost sites
In this article, we will explore some of the common raven’s most notable vocalizations and the contexts in which they use them.
Contact Calls
Ravens have a few short, simple calls that they use at a distance to identify themselves and locate other members of their social group. The most basic is their namesake “Tok!” call, a short croak or gurgle. Ravens give this call when approaching roosts or food bonanzas, re-establishing contact after becoming separated from a mate orSOCIAL GROUP. IT ALLOWS OTHER RAVENS TO PINPOINT THE CALLER’S LOCATION. Variations on the “Tok!” include “Tok-tok!”, “Korrrr”, and other guttural croaks.
Another common, longer distance contact call is a descending, drawn-out cry transcribed as “Paaaarrrr” or “Prruk-prruk-prruk.” This call seems to rally ravens together and get their attention. It is often given by birds arriving at feeding sites. Ravens will give responding “Paaaarrr” calls, becoming increasingly excited. Contact calls help ravens keep track of each other and congregate at promising food bonanzas and notable events in their territory.
Alarm Calls
Ravens produce rapid, harsh alarm calls to recruit others to mob potential threats. The classic alarm call is a short, sharp “kraa!” or “kraa-kraa!” These alarm calls prompt other ravens to join in mobbing predators like hawks, eagles, coyotes, and even humans they perceive as threatening. The more ravens responding to an alarm call, the louder and more intense the mobbing. Alarm calling and mobbing help ravens cooperatively drive predators and competitors away from food sources and nesting territories.
Ravens give slightly different alarm calls for ground versus airborne threats. They use deep, hoarse alarm caws for ground predators and higher pitched calls for soaring raptors. By distinguishing between ground and aerial predators in their calls, ravens can better direct the mobbing response. Ravens will also make non-vocal snapping sounds with their bills during aggressive mobbing. The sharp bills clacking together produces an intimidating sound to scare off intruders.
Food Calls
Upon discovering food like a carcass, ravens become very excited and vocal. They issue distinctive food calls that attract other ravens to share in the meal. These food calls include loud, extended yelping or sharp twittering noises often transcribed as “toc-toc-toc.” Food calls bring ravens rushing in to take advantage of feeding opportunities. Once gathered at a carcass, ravens continue to make loud bleating, barking, and yelping sounds as they jostle for position and tear into the meal.
Ravens sometimes make food calls deceptively when no food is present. Juvenile birds in particular will falsely food call to recruit others. When no food is discovered, the deceiving raven is chased and attacked by the flock. However, making some deceptive food calls can benefit juvenile ravens. Having a large flock assembled can allow them to gain access to a carcass they could not obtain on their own.
Roosting Calls
Ravens gather in large numbers at night to roost communally in trees or on cliff ledges. As ravens congregate at dusk, they signal to each other with greeting and roosting calls. These are deep, gurgling sounds, sometimes transcribed as “korrr-ork” and “kwaak-kwaak-kwaak.” The roosting calls seem to have a synchronizing effect, quieting the birds down to settle in for the night.
In the mornings, ravens resume roosting calls before leaving the roost to begin foraging. The morning vocalizations are longer and more complex than the evening roosting calls. Researchers hypothesize the extended morning vocal displays help ravens reestablish social connections after overnight separation and prepare for cooperative foraging during the day.
Aerial Displays
Ravens perform spectacular aerial displays at the nesting cliffs where they roost and breed. Particularly in spring, ravens engage in upside-down rolling flights, close pursuit, and spiraling dives. The aerial antics are accompanied by various excited vocalizations not typically heard at other times.
Ravens make long strings of bell-like “tok” notes during these aerial shows. Tok call sequences last up to 30 seconds as ravens loop, tumble, and chase each other. Researchers hypothesize the playful vocal displays help ravens assess each other’s flying performance for future partnership and synchronize breeding activity at roost sites.
Song
Common ravens have a long, complex vocalization described as “song.” Songs last up to a minute and feature a mix of gurgling, metallic clicking, whistles, and bell-like notes. Each raven has a unique song that distinguishes it from other individuals.
Ravens sing most frequently right before and after breeding season during nest building and incubation. However, ravens may sing year-round, especially when occupying a nesting territory. Song likely evolved to signal possession of a nest site since it occurs most often at breeding areas. The variety and individual uniqueness of raven song also suggests a role in courtship displays and mate communication.
Non-vocal Sounds
In addition to vocal calls, ravens produce a diversity of non-vocal sounds. Most notably, they clack their bills loudly during social interactions and aggressive encounters. Bill-clicking accompanies intense threat displays as ravens establish dominance and compete over positions in the social hierarchy.
Ravens also make soft, muffled popping or knocking sounds by snapping their thumbnail against the bottom mandible of their bill. This creates a subtle percussion that emphasizes other vocalizations during displays. The bill clicking and snapping amplifies the effect of the ravens’ calls for neighboring birds.
Putting it All Together
Ravens combine their array of calls into complex vocal sequences and exchanges. Long dialogues between bonded pairs demonstrate the conversational capacities of raven language. For example, paired ravens take turns making various food and roosting calls back and forth to coordinate activities.
Ravens engage in non-vocal bill manipulation like clicks and snaps during many social interactions. They blend various alarm calls seamlessly into recruitment and mobbing interactions. And they punctuate the communal hubbub of a feeding frenzy with contact calls, food calls, bill clicks, song, and aggressive snarls.
By assembling diverse vocalizations in context-specific ways, ravens communicate about threats, food, roosting, courtship, and social hierarchy. Their large brains, adaptability, and social complexity allow ravens to develop multifaceted vocal behaviors more elaborate than in related corvid species. The common raven aptly demonstrates that bird calls have syntax and meaning.
Conclusion
The common raven produces a wide variety of vocalizations – at least 33 different calls by one estimate. Contact calls like “Tok!” help ravens identify one another and converge at feeding sites. Short, sharp alarm calls recruit others to mob predators, while longer food calls attract others to share in a meal. At nest sites, aerial display calls facilitate courtship and breeding. And each raven has a signature song used to mark territory. Ravens also make meaningful non-vocal sounds by bill-clicking and bill-snapping.
This blend of calls, songs, and bill manipulation allows ravens to coordinate complex social behaviors. Their vocalizations have meaning and syntax – true language. Ravens assemble calls in contextually appropriate ways to convey information. This ability reflects advanced intelligence and adaptation that allows the common raven to thrive across diverse Northern Hemisphere habitats.
