Crows continue to demonstrate that they are very brainy birds. In fact, their intelligence can rival that of 7-year-olds. For example, a recent study published in PLoS ONE reported that crows completed an "Aesop's fable paradigm" task, which required crows to drop stones into water to rise the water level so the hungry birds could obtain an out-of-reach reward.
"Understanding causal regularities in the world is a key feature of human cognition," lead author Sarah Jelbert, a researcher at Auckland University, and her team point out.
Based on their findings then, crows share a sophisticated awareness of cause (not to mention caws) and effect possibilities that are on par with human skills.
Honeybees can count, categorize similar objects like dogs or human faces, understand "same" and "different," and differentiate between shapes that are symmetrical and asymmetrical.
Honeybees help to prove that "animals with bigger brains are not necessarily more intelligent," according to Lars Chittka, a professor of sensory and behavioral ecology at Queen Mary's Research Center.
Dogs understand arithmetic, according to Stanley Coren of the University of British Colombia's Department of Psychology.
Studies show, for example, that dogs notice errors in simple computations, such as 1+1=3. The average dog, Coren said, can learn 165 words.
"Super dogs," meaning those in the top 20 percent of canine intelligence, can learn at least 250 words and signals. Intelligence, at least as measured by humans, varies per breed, with border collies tending to be the brightest.
Jeff Kubina, Wikimedia Commons
Fish can distinguish between larger and smaller quantities, with an additional ability to "count" up to three, according to research on tropical angelfish. Fish, as well as dogs, probably have even more advanced mathematical ability, scientists suspect, but we need more methods to better study these animals.
Angelo Bisazza, a professor in the Comparative Psychology Research Group at the University of Padova, told Discovery News that such research is "slowly unraveling the cognitive abilities of fish and, as for the case of numerical abilities, they often suggest that the capabilities of these creatures are not so dissimilar from those of the organisms (monkeys, rodents and pigeons) that have traditionally been employed for these studies."
Cockatoos have been nicknamed "animal master-burglars" because they can pick almost any lock.
In a University of Vienna study, an adult male cockatoo named "Pipin" retrieved a nut after picking a lock that required him to: remove a pin, then a screw, then a bolt, then turn a wheel 90 degrees and then shift a latch sideways.
The task, which could stump many people, took Pipin -- unassisted -- less than two hours to figure out.
Yathin Krishnappa, Wikimedia Commons
An Asian elephant male named Koshik can imitate human speech, speaking words in Korean that others who know the language can understand, a Current Biology study determined.
The elephant's vocabulary at present consists of at least five words: annyong (hello), anja (sit down), aniya (no), nuo (lie down), and choah (good). Given that elephants have a trunk instead of lips, it's no small feat that Koshik can speak Korean.
"Some of the words were commands that Koshik learned to perform, such as 'lie down' and 'sit down,' or were given as feedback, and we have every reason to believe he understands the meaning of these words," co-author Tecumseh Fitch, a professor of cognitive biology at the University of Vienna, told Discovery News.
Tiefflieger, Wikimedia Commons
Goldfish not only listen to music, but they also can distinguish one composer from another.
A study, published in the journal Behavioral Processes, involved playing two pieces of classical music near goldfish in a tank. The pieces were "Toccata and Fugue in D minor" by Johann Sebastian Bach and "The Rite of Spring" by Igor Stravinsky.
The goldfish had no trouble distinguishing the two composers. While fish, and most other animals, prefer silence to music, the research proves that goldfish can detect complex properties of sounds, such as pitch and timbre.
Snakes do not just kill on instinct; they monitor the condition of their victims right until the very end, a Biology Letters study found.
The tightness and duration of a constricting snake's death squeeze are timed to perfection, matching the heartbeat and weakening state of the snake's unlucky prey. It takes smarts to do this, with scientists now wondering what other brainy feats snakes might be capable of achieving.
Horses never forget their human friends. Kevin Law, Wikimedia Commons
Human friends may come and go, but a horse could be one of your most loyal, long-term buddies if you treat it right.
Horses possess "excellent memories," Carol Sankey of the University of Rennes told Discovery News. She added that "horses are able to learn and memorize human words," and can hear the human voice better than even dogs can, due to their particular range of hearing.
Dolphins are second only to humans in brainpower.Heather Paul, Flickr
When human measures for intelligence are applied to other species, dolphins are second only to Homo sapiens in brainpower, according to Lori Marino, a senior lecturer in neuroscience and behavioral biology at Emory University.
"If we use relative brain size as a metric of 'intelligence' then one would have to conclude that dolphins are second in intelligence to modern humans," Marino, who performed several MRI scans on dolphin brains, told Discovery News.
It should then come as no surprise that a dolphin recently emitted the whistle for the word "sargassum," referring to a type of seaweed commonly found in the dolphin's marine environment.
In the future, high-tech devices might allow people and dolphins to hold conversations with each other. Given how much damage humans have done to the environment and to other species, we might get quite an earful.