March 28, 2008

Crows Collecting Shiny Objects

Stupid Question ™
Nov. 7, 2002
By John Ruch
© 2002

Q: Why do crows collect shiny objects?
—Gingerkitten Telekinesis

A: If you root around in a crow’s nest expecting to find an avian Aladdin’s Cave of gold watches, coins, rings or even bottle caps, you will be sorely disappointed.

Crows, ravens and magpies—all similarly accused of this superficial obsession—prefer to line their nests with soft moss, grass or animal fur.

These birds do horde food items, are known for stealing food (even from kitchen tables, if they have access), and may show an attraction toward certain non-edible items. They don’t collect shiny objects per se, but may (extremely rarely) take them and even hide them someplace as an outgrowth of these behaviors.

Anecdotes of these birds snatching up human valuables are plentiful, and many of them are undoubtedly true. Watches freshly removed in the outdoors are a favorite.

Birds are certainly capable of detecting shiny and colorful items. But in all these cases, the items are probably perceived as potential food, not as Crow Family knickknacks. And it is likely that the shape of the object is more important than its color and brightness.

Detailed reports from people who have raised crows and ravens in captivity provide some telling clues.

A classic 1927 report comes from Norman Criddle of Manitoba, Canada, who raised four young crows. He reported that they regularly collected a wide variety of objects together and then hid them. When they became older, they regularly hid food items for later eating—including shoving berries under a handkerchief in Criddle’s own front shirt pocket.

This tallies with modern observations that young birds aren’t sure of the food value of all the various items they see day to day, so they hide some to experiment with later.

It is quite likely that many of the “shiny object” theft reports are the work of young birds experimenting with possible food.

Bernd Heinrich, a University of Vermont biology professor, got even more detailed information in his work with young ravens. He was intrigued when he gave them an egg and they immediately attempted to eat it, even though they had never seen one before.

Presenting them with objects, both edible and inedible, of various shapes, he found they would faithfully attempt to eat any smooth, rounded object—including hickory nuts (which they found they didn’t like), a Ping-Pong ball, film canisters and a red-and-white fishing float.

He also found that bright color was not so important to them, as their response when presented with a variety of flowers was idiosyncratic. (There’s not an edibility problem here; ravens, like crows and magpies, are omnivorous.)

He also experimented by secretly burying a piece of roadkill they liked in different places under snow. He found they used sight—visual cues in the disturbances of the snow—rather than smell to find the roadkill again. This shows sight is critical to the birds’ food-finding.

Our small valuables—coins, rings, watches—tend to be smooth and rounded. It’s likely the birds simply consider them a meal, and dump them later when it’s clear they’re not.

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