American Crow—Photo: Mary Ellen Cross/Audubon Photography Awards
“Birds of a Feather”
by Jane Nicholas and Ida Domazlicky
Recently I’ve seen American Crows carrying snails in their beaks, and I’ve watched them drop the snails onto pavement. They were dropping them from just the right height to shatter the shells and get to the delicacies inside, and they were having quite a feast.
Gull dropping clam—Photo: Jane Nicholas
We’ve also seen gulls using a similar tactic to crack open clams at the beach (see photo). It’s common to see crows hanging out with gulls and foraging near the water, so it makes me wonder: Who taught whom this clever method of getting at the morsels inside the shells? Of course, I looked up “crows dropping snails.” It turns out scientific articles have been written about this behavior. Rather than being rare, it’s fairly common. The clam‑dropping behavior of gulls has been studied even more extensively. One study noted—unsurprisingly—that young gulls were less skilled than adults. They would often drop the same clam over and over without success, sometimes even missing the hard surface needed for a good crack. Adults, on the other hand, could gauge the size of the clam and how high they needed to fly to break it open—larger clams, higher drops—and they had better aim.
As you know, young American Crows often stay with their parents for several years. During that time, they’re learning as well as helping with younger siblings. This clever trick could easily be one of their lessons.
Both crows and gulls have been known to use tools to get to food. Gulls will use bits of human food as bait for fish. Crows will fashion a stick to fit into a knothole to reach a treat. So it really shouldn’t be surprising that both species have found ways to crack open shells. I still haven’t found an answer to my original question of who taught whom. Perhaps gulls and crows discovered the technique separately, but given that they spend time together, it’s possible one learned from the other. Either way, it’s quite clever. Bird behavior is fascinating. They continue to surprise and amaze me.