Male blue grosbeak on the left, female on the right.

Sexual dimorphism in birds refers to plumage, size, and other differences between the sexes. The color differences of the feathers among songbirds can be striking as illustrated by the blue grosbeaks above.

the multicolored drake has a prominent green crested head.

Among waterfowls, the colorful drake often has additional ornamentation which the plain hen lacks as seen in these wood ducks.

Among the birds of prey, the female bald eagle can outsize the male by up to 25 percent. Bill lengths can also vary. The female long-billed curlew’s bill is longer than the male’s.

Female Wilson’s phalarope. Length: 8.7–9.4 inches, weight: 1.3–3.9 ounces, wingspan: 15.3–16.9 inches.

But not all birds follow these general morphologic trends. The Wilson’s phalarope is an exception in which the female is more colorful than the male. The breeding female Wilson’s phalarope has a black stripe through its eye extending down the neck, blue-gray back and rusty color on its neck. Male lacks the dark stripe and is duller overall.

Left: female belted kingfisher. Right: male belted kingfisher. Length: 11.0–13.8 inches, weight: 4.9–6.0 ounces, wingspan: 18.9–22.8 inches.

The belted kingfisher is another example where the female is more colorful. The blue-gray and white female has an additional chestnut band across her belly which the male lacks.

Bird Walks: Aug. 3 and Sep. 7. Two options: 7:30–10am or 8–10am (choose a 2-hour or a 2.5-hour walk.) Both walks are free, but you must RSVP at blufflake.org/birdwatching. All are welcome. Bring your own binoculars, or borrow a pair. 11255 MLK Blvd. Search FrontPorchNE.com for “Bird Sightings” to see all the past bird stories and photos from George Ho.