For the final animal on our list, we come back to the pigeon, better known on your dinner plate as squab. So maybe they aren't quite doing calculus, but these birdbrains actually are quite talented at math. The street pests can learn abstract rules about numbers, demonstrating an ability to count off shapes, rank them in ascending order, and perceive differences in numbers of groups of objects [source: Gorman].
Beyond math, pigeons have shown that they're able to recognize people who've been hostile toward them in the past and avoid them in the future [source: Gibson]. They can also recognize themselves in prerecorded videos [source: Toda and Watanabe]. Lastly, while you think these birds may be uncultured annoyances, they may be able to one-up you in museums, discriminating between Monet and Picasso paintings [source: Watanabe et al.]. Not bad for a bird you may order up to eat in a restaurant.
Author's Note: 5 Food Animals That Are Smarter Than Your Pet
I'd heard that pigeons were smart before, but it wasn't until I delved into researching this article that I truly got a good grasp of their intelligence. I'm not generally an animal hater – quite the opposite, actually. But pigeons are in another category altogether. Let's just say I'm not fond of them, to put it mildly. But now that I know how smart they are, I kind of feel like I should tip my hat to them. The birds are practically born with degrees in math and art history. Seriously?!?
- Angier, Natalie. "Pigs Prove to Be Smart, if Not Vain." The New York Times. Nov. 9, 2009. (Jan. 17, 2015) http://www.nytimes.com/2009/11/10/science/10angier.html
- Apple, R.W. Jr. "Much Ado About Mutton, but Not in These Parts." The New York Times. March 29, 2006. (Jan. 17, 2015) http://www.nytimes.com/2006/03/29/dining/29mutt.html?pagewanted=all&_r=0
- Bittman, Mark. "Octopus Demystified." The Splendid Table. Dec. 12, 2000. (Jan., 17, 2015) http://www.splendidtable.org/story/octopus-demystified
- Borrell, Brendan. "Are Octopuses Smart?" Scientific American. Feb. 27, 2009. (Jan. 17, 2015) http://www.scientificamerican.com/article/are-octopuses-smart/
- Broad, William J. "Squids Emerge As Smart, Elusive Hunters of Mid-Sea." The New York Times. Aug. 30, 1994. (Jan. 18, 2015) http://www.nytimes.com/1994/08/30/science/squids-emerge-as-smart-elusive-hunters-of-mid-sea.html?pagewanted=1
- Gibson, Megan. "Pigeons Remember That You Hate Them, Will Probably Plot Revenge Later." Time. July 6, 2011. (Jan. 18, 2015) http://newsfeed.time.com/2011/07/06/pigeons-remember-that-you-hate-them-will-probably-plot-revenge-later/
- Gorman, James. "How Smart Is This Bird? Let It Count the Ways." The New York Times. Dec. 22, 2011. (Jan. 18, 2015) http://www.nytimes.com/2011/12/23/science/pigeons-can-learn-higher-math-as-well-as-monkeys-study-suggests.html?_r=2&
- Gray, Richard. "Sheep are far smarter than previously thought." The Telegraph. Feb. 20, 2011. (Jan. 17, 2015) http://www.telegraph.co.uk/news/science/science-news/8335465/Sheep-are-far-smarter-than-previously-thought.html
- Kluger, Jeffrey. "Not Birdbrains Anymore: Scientists Discover Pigeons Can Count." Time. Dec. 28, 2011. (Jan. 18, 2015) http://content.time.com/time/health/article/0,8599,2103172,00.html
- Meyer, Fox. "How Octopuses and Squid Change Color." Smithsonian Institution. (Jan. 18, 2015) http://ocean.si.edu/ocean-news/how-octopuses-and-squids-change-color
- Schwartz, Mark. "Smart squid may unlock the secrets of how animals and people learn." Stanford University News Release. March 22, 2000. (Jan. 18, 2015) http://web.stanford.edu/dept/news/pr/00/000323gilly.html
- Schweid, Richard. "Octopus." Reaktion Books. 2014.
- Toda, K.; Watanabe, S. "Discrimination of moving video images of self by pigeons." Animal Cognition. Vol. 11. pp. 699-705. October 2008.
- Watanabe, Shigeru; Sakamoto, Junko; Wakita, Masumi. "Pigeons' discrimination of paintings by Monet and Picasso." Journal of the Experimental Analysis of Behavior. Vol. 63. pp. 165-174. March 1995.
- Williams, Wendy. "Kraken: The Curious, Exciting and Slightly Disturbing Science of Squid." Abrams Image. 2011.
HowStuffWorks takes a look at gastroliths, or 'stomach stones' and why some animals eat them.