Photograph by: Vincent J. Musi, National Geographic March 2008
Biologists as far back as Darwin have pondered whether animals can think and have feelings. It was the famed naturalist who proposed that animal minds (and human ones, of course) must have evolved as other traits had, developing the necessary skills to function in their particular environment. Not everyone agreed with this view, however. The predominant theory in the first half of the 20th century was behaviorism, the idea that animals are incapable of conscious decision-making and that all of their actions can be explained in terms of innate behavior.
Today the field of animal cognition has moved beyond behaviorism to embrace many new areas of study. Most of the work involves animals in captivity because so many variables are encountered in the wild. Some of the animals studied and the findings on their cognitive abilities are listed below.
Azy (orangutan) communicates through abstract symbols on a computer screen and has shown that he can understand another individual’s perspective, a capability scientists call theory of mind.
Momo (marmoset) learns through imitation and has a sense of object permanence—the knowledge that something out of sight still exists.
Aristides (ring-tailed lemur) can repeat arbitrary sequences on a computer screen and discriminate between quantities.
“Betsy” and Rico (border collies) understand hundreds of words and the objects they represent.
Elephants have been shown to exhibit self-awareness and have long memories.
Sheep can recognize individual faces—human and sheep—and retain the recognition long-term.
Octopi use tools, exhibit play behavior, recognize individuals, and have distinct personalities.
African cichlids determine social ranking through observation, exhibits signs of logical reasoning.
Many animals have been observed using simple vocal signals among themselves. Now for the first time, scientists believe they have evidence of a nonhuman mammal combining signals to create entirely new meanings. Male putty-nosed monkeys in Nigeria have been observed stringing together calls of pyow and hack. Males of many monkey species commonly repeat pyow or hack for warning females and their young charges. Used alone, the call means a predator may be ready to attack, says researcher Klaus Zuberbühler. In sequence as the putty-nosed monkeys use them, he says, there might not be a specific danger, just the male’s urge to get moving.
Putty-nosed monkeys repeat basic calls to sound an alarm:
Pyow: A leopard or other predator is lurking nearby.
Hack: An airborne predator, such as an eagle, is close.
They combine the calls to create a simple “sentence”:
Pyow pyow hack hack hack hack. Let’s leave this place and go elsewhere. —Chris Carroll
Like any group house, honeybee hives can get too crowded. When a hive is simply bursting, the honeybee residents engage in a collective decision process that could inspire even the best-run commune. The queen and about half the hive fly to a tree and wait while scouts fan out to look for a new home. According to a study published in American Scientist, scouts that find good nesting spots compete against each other to recruit undecided scouts to their sites by doing a “waggle dance.” Recruits will then inspect the site for themselves. If they like the spot, they too will waggle dance to advertise it. Once 15 or more scouts converge on a single site, they return to their queen and waiting hive mates. The scouts then press their vibrating thoraxes against the waiting bees to warm up the latter for flight. When all are ready, the whole group flies to its new home. The study notes that because each scout judges a site independently, only truly good sites attract more waggle dancers and end up being chosen by the group.
If you hear a cell phone ring outdoors, you may be startled to discover that the “phone” has feathers. Master mimics, starlings were taught by the Romans to imitate human speech. Today their repertoire includes not only other birdcalls but also sirens, chain saws, horses whinnying—and the warbling of cell phones. Starlings as far apart as Denmark and Australia have learned the trick. Males re-create human sounds “especially at breeding time to attract a mate and hold territories,” says Andrew South of Britain’s Royal Society for the Protection of Birds. Starlings may not be alone. As cell phones proliferate, mockingbirds, mynahs, and other mimics are likely to get into the act.
“Caller ID: The Birds.” National Geographic (May 2002).
Bekoff, Marc. Animal Passions and Beastly Virtues: Reflections on Redecorating Nature. Temple University Press, 2006.
Cheney, Dorothy L., and Robert M. Seyfarth. How Monkeys See the World. University of Chicago Press, 1990.
Clayton, Nicola S., and Anthony Dickinson. “Episodic-like Memory During Cache Recovery by Scrub Jays,” Nature (September 17, 1998).
Griffin, Donald R. Animal Minds: Beyond Cognition to Consciousness. University of Chicago Press, 2001.
Herman, Louis M. “Exploring the Cognitive World of the Bottlnosed Dolphin.” The Cognitive Animal. Massachusetts Institute of Technology, 2002.
Hunt, Gavin R., and Russell D. Gray. “The Crafting of Hook Tools by Wild New Caledonian Crows.” Proceedings of the Royal Society London (2003).
Pepperberg, Irene M., and Jesse D. Gordon. “Number Comprehension by a Grey Parrot (Psittacus erithacus), Including a Zero-Like Concept.” Journal of Comparative Psychology. (2005), 197-209.
Pruetz, Jill D., and Paco Bertolani. “Savanna Chimpanzees, Pan troglodytes Verus, Hunt With Tools.” Current Biology (March 6, 2007).
Savage-Rumbaugh, Sue, and Roger Lewin. Kanzi: The Ape at the Brink of the Human Mind. John Wiley & Sons, 1994.
Van Schaik, Carel. Among Orangutans: Red Apes and the Rise of Human Culture. Belknap Press, 2004.
Van Schaik, Carel P., and others. “Orangutan Cultures and the Evolution of Material Culture.” Science (January 3, 2003).
Weir, Alex A.S., Jackie Chappell, and Alex Kacelnik. “Shaping of Hooks in New Caledonian Crows.” Science (August 9, 2002).
Whiten, Andrew, and Richard W. Byrne, eds. Machiavellian Intelligence II. Cambridge University Press, 1997.
Wynne, Clive D. L. Animal Cognition: The Mental Lives of Animals. Palgrave, 2001.
Other National Geographic Resources
Chadwick, Douglas H. “Listening to Humpbacks.” National Geographic (July 1999).
Miller, Peter. “Swarm Theory.” National Geographic (July 2007).
Moffett, Mark. “Ants: Able Bodies.” National Geographic (August 2007).
Patterson, Francine. “Conversations With a Gorilla.” National Geographic (October 1978).
Payne, Katharine. “Elephant Talk.” National Geographic (August 1989).
Vessels, Jane. “Koko’s Kitten.” National Geographic (January 1985).
Warren, Lynne. “Calls in the Wild.” National Geographic (March 2004).
Weintraub, Boris. “Kanzi’s at the Joystick, More Than Just a Game.” National Geographic (February 1994).
Last updated: January 28, 2008
By Christopher D. Bird and Ira G. Federspiel, University of Cambridge
Have you ever scanned the sky after hearing the distinctive screech of a buzzard only to find a shifty-looking Eurasian jay peering back at you? Remarkably, the jay may be the perpetrator of the sound. Like parrots, jays have an amazing capacity for mimicry, the ability not only to copy the songs of other birds—the trill of a blackbird, the chacker-chacker of a magpie, the fluting song of the bullfinch—but to incorporate such wide-ranging sounds as dripping faucets and human speech into their repertoire. (Jays can confuse us in another way too: The bird is inconspicuous and more likely to be heard than seen. Bird-watchers who spot the blue flash of its wing often turn in erroneous reports of some tropical species that's magically appeared in British back gardens.)
Jays aren't the only birds that mimic other species' songs. Most corvids and a number of other songbirds—including drongos, grey parrots, and starlings—also have that capacity.
Reports of mimicking jays come both from captive populations and the field. In fact, the ability is so widespread it's likely that the bird's tendency to mimic sound is innate. This leads one to ask: What is the phenomenon's adaptive value? Why do birds mimic sounds? The researcher Raeburn suggested as far back as 1949 that the jay appropriates the notes of the carrion crow and tawny owl when its young are threatened in order to frighten the enemy. However, Derek Goodwin, the late ornithologist who wrote Crows of the World, pointed out that the jay would often use the call of the weaker blackbird under similar circumstances, suggesting that Raeburn's theory was unlikely. More than two decades later, Eugene Morton observed that thick-billed euphonias mimic the mobbing calls of several species of small songbirds when under attack—the potential predator may be scared away by the threat of being mobbed by large numbers of these smaller birds.
Some evidence suggests a correlation between the uttering of a copied sound and an emotional state similar to that when the bird first heard the sound. This might explain the use of predator calls when a bird is frightened or under attack.
A more likely explanation for why birds mimic may be that it helps in sexual selection. It has been suggested that mimicked sounds could be an "honest signal" to females indicating the quality of the male. Since copying a sound that's not part of the species' own repertoire comes at a certain expense, time and energy expended in mimicking suggest a healthier suitor. Hence vocal repertoire may help females decide which males to mate with. There's evidence that this may be true for starlings: Andrew South of the Royal Society for the Protection of Birds says that male starlings re-create human sounds "especially at breeding time to attract a mate and hold territories."
Female jays also mimic sounds, suggesting that if sexual selection is the key, then the choice, at least in this species, goes both ways. Goodwin's reports of nearly 60 years ago cite a female jay using the sound of a lawn mower in a sexual context. He goes on to describe the excitement induced by the note in both a captive male and a wild male intruder. Although one might wonder how the wild jay knew that the copied sound was a sexual invitation, the copied sounds do not appear to cause confusion or misunderstanding among jays. Perhaps the birds take their cue from the tone and intensity with which the notes are uttered or from the caller's actions if he or she is visible.
How does a new sound spread?
Goodwin's example leads to the question of how copied sounds spread though a population. To what degree do animals learn novel vocalizations from one another? Are all individuals equally skilled at detecting and reproducing novel sounds, or do they learn at a different pace or with a different level of accuracy? We and other researchers at the University of Cambridge hope our group of captive, hand-raised jays will provide some answers. These young jays can frequently be heard mimicking vocalizations of other bird species (among others, a buzzard, tawny owl, blackbird, zebra finch, magpie, and jackdaw) as well as a plethora of artificial sounds (an ambulance siren, whistling) and human speech.
What to mimic?
Jays appear to favor mimicking high-pitched sounds, although this is not absolute. Goodwin noticed that his jays readily mimicked a human whistle but never copied the cooing of nearby doves. We may wonder what, to a jay, constitutes a "good" sound to mimic and what doesn't. Vocal control does not seem to be a problem; a bewildering variety of bubbling, cackling, and hissing sounds can be heard at jay gatherings. These birds may mimic the lowing of cattle, the crackling of fowls as they come running up to be fed, the deep tones of a man, or the high treble of a child. It seems there is much about vocal mimicry—a very peculiar behavior—that we do not know.
"Caller ID: The Birds." National Geographic (May 2002).
Catchpole, Clive K., and Peter J. B. Slater. Bird Song: Biological Themes and Variations. Cambridge University Press, 1995.
Dowsett-Lemaire, Francoise. "The Imitative Range of the Song of the Marsh Warbler Acrocephalus palustris, With Special Reference to Imitations of African Birds." Ibis. Vol. 121. (1979), 453-468.
Goodale, Eben, and Sarath W. Kotagama. "Context-dependent Vocal Mimicry in a Passerine Bird." Proceedings of the Royal Society B. Vol. 273. (2006), 875-880.
Goodwin, Derek. "Notes on Voice and Display of the Jay." British Birds. Vol. 42. (1949), 278-287.
Goodwin, Derek. "Some Aspects of the Behaviour of the Jay Garrulus glandarius." Ibis. Vol. 93. (1951), 414-442 and 602-625.
Hindmarsh, Andrew, M. "Vocal Mimicry in Starlings." Behaviour. Vol. 90. (1984), 302-324.
Morton, Eugene, S. "Vocal Mimicry in the Thick-billed Euphonia." Wilson Bulletin. Vol. 88. (1976), 485-487.
Pepperberg, Irene, M. "Grey Parrots Do Not Always ‘Parrot': The Roles of Imitation and Phonological Awareness in the Creation of New Labels From Existing Vocalizations." Language Sciences (2006).
Last updated: May 23, 2008