Urban challenges make city birds smarter than rural ones

The great tit songbird, a menace to milkmen everywhere.
(Photo by Joe Tobias)

Life is a lot harder for birds living in cities, but the challenges have apparently sharpened some birds' wits and made them smarter than rural birds. Read how in this article in Aeon by Menno Schilthuizen, an excerpt from his upcoming book Darwin Comes to Town: How the Urban Jungle Drives Evolution.

Some adaptations he describes seem sensible, and some almost defy belief. Carrion crows in the Japanese city of Sendai, for example, figured out an excellent way to break open walnuts. The local walnuts are too tough for them to crack, so country crows fly high and drop the nuts on rocks to break them. Sendai crows, though, realized the nuts would crack easier when dropped under the wheels of slow-moving cars.

A songbird called a great tit was also well-known for its puzzle-solving prowess in early 20th century England. Some figured out how to open the glass bottles of milk left at doorsteps in the morning. Birds can't digest lactose, but the layer of cream at the top of the bottle contains very little lactose and a lot of fat that birds need in the winter. Dairies tried to stymie the birds with wax-sealed caps, then aluminum, but tits figured out how to open both. After dairies began offering skim and homogenized milk (which have no layer of cream on top), tits learned which color cap denoted whole milk and, apparently, were able to teach their friends the secret.

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