This redwing was discovered in a Portland flock of robins in January. It's only the second time this robin-like European species has ever been discovered in Maine. Credit: Courtesy of Doug Hitchcox

I know what you’re thinking. “Oh, no, not another Zoom meeting!” Relax. Next Friday night, Feb. 19, I’ll be doing a webinar on how to identify birds quickly. It’s this month’s free program for the Penobscot Valley Chapter of Maine Audubon. For those who can’t attend, I’ll spill the beans right here and now.

The first point I’ll be making is this: size matters. Color may catch the eye, but size is the first thing the brain registers. Perhaps that’s a throwback to our prehistoric ancestors, who had to make a quick judgment about whether a predator was big enough to eat them.

A particular bird species may have confusing color variations, depending on age and gender, but seldom does it vary in size. Young bald eagles go through several color plumages before reaching adulthood, but once they’re out of the nest, every eagle is eagle-sized. The first step in quickly identifying a bird is to judge its size.

Birds come in all sizes, from hummingbird to ostrich, but fortunately a lot of them can be grouped together by comparing them to common birds you already know. Your brain does it automatically. You can quickly judge if a bird is chickadee-size, robin-size, crow-size or larger. It’s often the first thing somebody says when they ask for help in identifying a bird: “It was yellow, about the size of a robin.”

A lot of birds can be grouped by size, but within each group, there is likely to be one that is much more common than all the others. It sort of becomes the default bird — the one you expect to see. When you see a bird in that size category, it’s natural that the next step is to determine whether it is your default bird, or not your default bird. For instance, sparrow identification is difficult. There are roughly 13 sparrow species that nest in Maine. But song sparrows are in every neighborhood following their arrival in April. Often, the first step in making a quick identification is to decide if a mystery sparrow is a song sparrow, or not a song sparrow.

In February, every hawk along Interstate 95 is a red-tailed hawk, unless it isn’t. On a summer mudflat, every shorebird is a semipalmated sandpiper, unless it isn’t. Every robin is a robin, unless it isn’t. Two robin-like birds from the West sometimes show up in Maine: Townsend’s solitaire and varied thrush. In January, an exceptionally rare redwing was discovered in a Portland flock of robins, only the second time this robin-like European species has ever been discovered in Maine. And the first step in identifying this thoroughly unexpected bird was to recognize that it wasn’t a robin.

Another tip: You are what you eat. The shape of every bird is largely determined by its diet. Wading birds have long legs, swimming birds have webbed feet, soaring birds have broad wings, etc. Bill shape is particularly determined by diet. The world is full of tiny, hard-to-identify birds. Often, a key step in figuring them out is to guess what they eat. Insect-eaters have thin bills, built for snatching bugs out of the air or gleaning them from under leaves. Seed-eaters have heavy bills, designed for cracking shells. The bigger the bill, the bigger the seed they can crack.

Probably the biggest secret to be revealed in the webinar is that color should always be treated with suspicion. Reds, blues and yellows may capture attention, but the colors are often unhelpful and even deceptive. A female scarlet tanager isn’t scarlet. A female redstart isn’t red. Scores of birds are yellow, and some species are virtually identical.

Birds have field marks, and any good guidebook takes pains to point them out. Fortunately, many of these marks fall into categories. About half of warblers have streaked breasts; half don’t. Same for sparrows. Roughly half of warblers have yellow throats. Half have wing bars. Noticing just one of these common field marks cuts the list of identification possibilities in half at a glance. Furthermore, a handful of birds have eye rings. Some have white outer tail feathers. Color can vary with age and gender, and change as birds molt into fall plumage, but most field marks remain fixed. It’s not hard to notice them. The trick is in remembering to look.

There. You are now free from the need to attend my Zoom webinar. Still, if you’re a glutton for punishment, please send an email to penobscotvalleyaudubon@gmail.com to sign up and get the link.

Bob Duchesne serves as vice president of Maine Audubon’s Penobscot Valley Chapter. He developed the Maine Birding Trail, with information at mainebirdingtrail.com. He can be reached at duchesne@midmaine.com.

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