Crows and ravens are extremely intelligent and under appreciated animals. Their family, the Corvidae, are responsible for an strikingly large number of complex and innovative behaviors, and rival primates in relative brain size (Taylor, 2014). Their intelligence evident, with behavior that ranges from clever and audacious to just plain silly. In addition to their problem solving skills and ability to use tools, these birds cooperate socially and have complex and contextually meaningful vocalizations. Parrots are the corvids’ only rivals for the most intelligent birds.

Crows and ravens are known for their ability to find solutions to problems and, at least a few species, use tools. The crows in Japan, for example, have learned to drop nuts at stoplights for the traffic to crush, than walk out when the cross light turns on to eat. Similarly, in this video New Caledonian crows show an understanding of water displacement. The birds are tempted with food floating in a tube of water and have to drop rocks into the tube to raise the water level until they can reach their treat.

A New Caledonian Crow with a tool.
Image by Gavin Hunt, from Science Daily

New Caledonian Crows are the species of corvid that is most renowned for their tool using abilities (Though the endangered Alala might be even more impressive). These clever birds have managed two particularly impressive feats. First, they make and modify their own tools. This includes hooks, which are practically unheard of in other animals. Second, they will use tools to get tools that are needed to access a food reward (Taylor, 2014), which can be seen in these two videos (a nicer version of the latter can be found here).

Tool use is not these birds’ the only notable achievement.

Almost all corvids are at least slightly social, with most pair bonding (mating) for life, rather than just a season as in most birds, and young crows and ravens will form cooperative gangs (Clayton & Emery, 2007). The American Crow in particular tends to form family groups consisting of a breeding pair and one or more years worth of offspring (Tarter, 2008). Affiliated birds will cooperate in fights (Clayton & Emery, 2007) and foraging (Tarter, 2008).  Mated crows, ravens, and the related rooks will spend a lot of time reinforcing their relationships with activities like preening, sharing food, and twining their bills (Clayton & Emery, 2007).

Rooks (A) bill twining and (B) preening each other.
Image from Clayton & Emery, 2007.

Corvids also have good memories for social relationships. In general, they can recognize the calls of of individuals of their species, and group them by their social relationship (Clayton & Emery, 2007). Ravens have been shown to remember this information for over three years, while American crows can remember human faces for a similar period of time (Taylor, 2014).

With this information in mind, it is not surprising that crows use a variety of distinct calls to coordinate their behavior (Tarter, 2008). American Crows  have at least nine types of call that produce different reactions depending on the listeners’ relationship with the caller, and their relative locations (Tarter, 2008). For example Tarter’s (2008) short call functions to attract family members to a foraging site, and the scream call is given to potential threats. The latter may attract unrelated crows, but only when directed at something like a hawk that the birds would mob (Tarter, 2008). This website has been created to gather data on the potential language and culture of the American Crow.

The ability of many corvid species to mimic human speech well documented. Both crows and ravens seem to speak discrete phrases in direct response to humans, whether or not they have any understanding of the meaning of those phrases (though I personally think the second half of that last video is evidence that they do). Magpies do this some as well, but tend to mix words in with other sounds in a song-like sequence. This seems similar to what lyrebirds do to me, in that the purpose may be to create a more complex song.

All in all, corvids, particularly crows and ravens, are impressive animals and ones I would like to see studied more thoroughly. As social, tool using animals with the ability to mimic human speech, corvids are excellent candidates for language studies. Who knows, we may find them to be as good as or better than the African Grey parrot.

 

Bits that didn’t make it (but I want to share anyway).

• New Caledonian crows also used sticks to poke at rubber snakes to see if they were alive (Taylor, 2014).
• Magpies can recognize themselves in a mirror, maybe other corvids can too (Taylor, 2014).
• This video.
• Also, this one.

References

Clayton, N. S., Emery, N. J. (2007). The social life of corvids. Current Biology, 17(16), R652–R656 http://dx.doi.org/10.1016/j.cub.2007.05.070

Hunt, G. [Photograph]. Retrieved from  https://www.sciencedaily.com/releases/2016/03/160315153329.htm

Tarter, R. (2008). The Vocal Behavior of the American Crow, Corvus brachyrnynchos (Unpublished doctoral dissertation). The Ohio State

Taylor, A. H. (2014), Corvid cognition. WIREs Cognitive Science, 5, 361–372. doi:10.1002/wcs.1286