Birding Notes

Reflections on birds and other wildlife on the edge of a southern woodland

Tuesday, September 18, 2007

Rose-breasted Grosbeak and Green Caterpillars

A female Rose-breasted Grosbeak was in our White Oak trees this afternoon, eating some kind of large green caterpillars. They must be good – while I watched her for only a few minutes, she ate three, one after another, and they seemed to be easy to find in the oak. Each one was large enough to take a few seconds for her to get down. She held one in her bill, shook her head and snapped repeatedly, for several seconds, until she eventually got it swallowed. As I’ve read in species accounts, she didn’t use the help of a foot or a branch to subdue a caterpillar – she just kept shaking it in her large, thick, pinkish bill until was subdued. After eating one, she rubbed each side of her bill quickly against a branch.

The green caterpillars also attracted a Red-eyed Vireo with a different eating style to the same tree later in the afternoon. The Vireo held each caterpillar by one end in its bill and slapped it against a branch several times before swallowing it in one quick snap. Then it, too, wiped its long, comparatively slender bill against a branch.

We only see Rose-breasted Grosbeaks here during spring or fall migration. They stand out among the smaller, flighty fall migrants like warblers, which often can be maddeningly elusive. Relatively large and stocky, the Grosbeaks are not delicate or subtle in either shape or movement. The male’s bold coloring – black back, pure white belly and rose-red splotch on the upper breast – identifies him immediately. The female is handsome rather than flashy, but still distinctive, with rich brown and cream-white plumage that blends more easily with a leafy autumn background – her head striped in very dark brown and white, with a broad white stripe over the eye, dark brown wings with white wing bars, flecks of white across the lower wings and back, and breast heavily streaked in dark brown.

At times even Rose-breasted Grosbeaks can go unnoticed, when they’re quiet and stay hidden in deep or high foliage, but they often come to feeders, and the ones I’ve watched around our yard – both male and female – have shown personalities as colorful and assertive as the male’s appearance. They’re never dull.


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