Monday, January 16, 2012

Crossbills vs. Hemlock

With some unseasonably warm weather lingering (but predicted to end), I headed out on a January morning to Hartwick Pines State Park. This is a real gem in Michigan's park system. It would be amazing in any state! Harboring some of the Midwest's last virgin White Pines, Hartwick Pines straddles what I like to call the Grayling Line. There's an imaginary line that goes through east-to-west through the town of Grayling, Michigan that unofficially marks the southern boundary of the "North". South of this line, you will rarely find boreal species of birds - or anything for that matter. Look at range maps for plants, birds, insects, reptiles, etc. in the Great Lakes region and you'll see an astounding number of organisms that call the Grayling Line either the northern or southern extreme of their range.

Thus, I like to bird here. In the summer, some of the northern birds common in the far north will nest this far south. And in the winter, you can have an experience like I had this week.

I was strolling along, enjoying the smell of a grove of Eastern Hemlocks. (This is also the line where hemlocks start becoming scarce, although you can find them much farther south in Michigan, they are far less common. Luckily the Hemlock Wooly Adelgid hasn't gotten here...yet.)

While watching a Red-breasted Nuthatch bouncing on a log, I heard a flutter of many wings and some frenzied flight calls just before the hemlock above my head burst into movement. Every branch was swinging and hemlock cone refuse was raining on me. The tree I was standing under was suddenly being brutalized by a flock of White-winged Crossbills.

Crossbills are fascinating birds. Their bills are indeed crossed, so that it appears they have a deformity that would make feeding problematic if not impossible. It turns out that bill adaptation is ideal to give the bird leverage to pry open conifer cones to extract it's favorite food, seeds. I'd seen Red Crossbills (Loxia curvirostra) on Lopez Island in Washington, but all my looks at White-winged Crossbills (Loxia leucoptera) had been poor. A fleeting glimpse of a flock here and there. On this blessed morning, I got all I wanted and more.

You can see how it got the crossbill well as the white-winged part.

White-winged Crossbills strongly prefer hemlock and spruce trees for foraging. If you live up north, and there's a good cone crop on some local trees, stake it out and treat yourself to a crossbill feeding frenzy.

This one was reaching for a cone. I love the coloring of the breast.

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