Sunday, November 30, 2014 NW Crow Choreography

Seward, Alaska

As the shadows lengthened into dusk yesterday afternoon, I enjoyed watching the industrious NORTHWESTERN CROWS at the Greenbelt beach. The tide was out and the table set. The crows enacted a rhythmic vertical ballet as one after the other flew high, paused, then plummeted back to the beach. I had to look closely to see the other participant in this performance, a small blue mussel free-falling just ahead of the pursuing crow.

Once landed, the crows took a few seconds to toss back the treat served on a half-shell, then carefully selected another blue mussel. They quickly tore the strong byssal thread anchor lines and plucked the once-sessile mollusk from its rocky anchorage. Suddenly airborne, the mussel became a mini-astronaut, then a missile, then dinner. Eeeeeeeeee! Quite an exciting finale for a humble clam.

It was fascinating to observe their graceful and clever use of gravity and hard rocks to loosen the blue mussel’s tenacious lock.

According to the USDA, mussels are low in calories and fat but high in protein and many essential vitamins and minerals, especially B-12, selenium, and manganese. One medium blue mussel has only 12 calories, so those crows are working pretty hard!

Salmon, however, are much more calorie-dense. BALD EAGLES of all ages perched in trees, on power pole eagle perches, sat on the beach, and waded in Scheffler Creek to grab a carcass. Similar high numbers of eagles repeated at the Lagoon, in the surrounding trees, on every eagle perch, and even stood on the thin ice, attracted by the quantity of salmon carcasses. RAVENS and MAGPIES ate their share too, often just out of beak range at the eagle’s table.

I don’t know why the crows choose to dance for their mussel dinner when they could be feasting on salmon, but it sure is fun to watch.

Happy Birding!
Carol Griswold

Seward Sporadic Bird Report Reporter

No comments:

Post a Comment