Seeds on Maine spruce trees drawing crossbills

While visiting friends on Deer Isle recently, we were having a congenial lunch on a porch overlooking Eggemoggin Reach, the body of water spanned by the bridge to Deer Isle.

Suddenly, a small flock of white-winged crossbills flew in. They landed in the top of a spruce tree. All conversation stopped while we watched the birds prying the cones apart to eat the seeds within.

We saw a male crossbill, bright pink with white bars on his black wings. His bright color made him stand out. The better-camouflaged female, whose color was mostly olive green, was also quite attractive, and she was busy getting seeds from spruce cones. Most birds have symmetrical bills with upper mandibles that are broader than the lower mandibles. The lower mandible fits inside the upper one.

A crossbill’s bill is not symmetrical – and the lower mandible does not fit into the upper one.

The distal half of the crossbill’s top mandible crosses over the bottom mandible. When the bird wants to eat spruce seeds, it usually perches on the branch above the cone and reaches down.

With its bill, it pries the scale away from the cone by separating the two mandibles in opposite directions. Then the crossbill takes the two seeds from under the scale and eats them.

You can mimic this movement with your right hand. Make a fist with your thumb outside of your fingers. Then extend your index finger over your thumb. There’s the crossbill’s bill.

Then move your index finger toward your eyes. That’s how the crossbill wedges the scale away from the cone. And those seeds must be delicious. You might have tried pine seeds from the Southwest – those delicious seeds are bigger than what our state tree produces.

Canadian ornithologists say that Canadian spruce trees are not producing seeds this year. White-wing crossbills are irrupting – irruptions are irregular migrations that some bird species undertake en masse in winter to find food – from Canada into Maine.

Along the coast, our spruce trees are producing a good crop of cones, and these crossbills feed on small cones that grow on spruce, hemlock and larch.

Keep your eyes peeled for crossbills this fall and winter. You may see white-winged crossbills this winter; you may see red crossbills too, but that’s another species and another column.

For information on Fields Pond Audubon Center, call 989-2591.