By Bryan Stevens
During a recent bird count in Unicoi County with some fellow members of the Elizabethton Bird Club, a participant discovered a fledgling bird in an ornamental holly tree. The young bird was first identified as a young gray catbird, but then an adult song sparrow began chirping and lingering in the vicinity. The song sparrow’s attentiveness triggered a reassessment of the initial identification of the fledgling.
The grayish fledgling, bigger than an adult song sparrow, was, even at a glance, obviously not a sparrow. It wasn’t a catbird, either. The bird was a young brown-headed cowbird, and the attentive song sparrow was a blissfully unaware foster parent. The complicated path of identifying the young cowbird reminded me that it’s not always easy to tell one bird from another.
No brown-headed cowbird ever knows its biological parents. Female brown-headed cowbirds have evolved a “cheat” that allows them to slip their own eggs into the nests of unsuspecting foster parents of various species.
Young cowbirds, as well as adult female cowbirds, are arguably North America’s most nondescript birds and often baffle first-time observers.
The identification of birds can be a challenging undertaking, and the birds don’t always make it easy. Male and female birds can present completely different appearances to observers. Such gender-based differences in appearances are described by scientists as sexual dimorphism. These occasional birds of a “different feather,” so to speak, can sow confusion and frustration for new birders and even more seasoned ones.
A well-known example in the bird world is the bird known as the Indian peafowl, or more often commonly called “peacock.” In these fowl, however, males are known more accurately as “peacocks” and females as “peahens.”
The male peafowl, a bird sacred to the mythological Greek goddess Hera, sports iridescent blue and green plumage. The tail feathers are marked with “eyespots” that are put on full display when the male fans out his tail to show off to watching hens. The hens, as is often the case among birds, are much more dull than males. The female Indian peafowl’s plumage mostly consists of muted browns, grays and greens that don’t come close to rivaling the showy male’s feathers.
The world’s various orioles are often quite brilliantly colored with orange, yellow and black plumages the norm in males. A great deal of sexual dimorphism exists between male and female orchard orioles. The male sports a chestnut-orange and black plumage, but the female is a rather lackluster greenish-yellow. Identifying these orioles is complicated by the fact that a young male in his first year after hatching presents an appearance unlike either adult males or females.
A young male will more closely resemble a female with a basic mustard-yellow plumage, but he also sports a black throat and some black feathers around the bill. The first time I ever saw a young orchard oriole, I had no knowledge of its differing appearance and thought I’d found some strange new bird.
In a similar fashion, young male American redstarts also look like a strange blend of the appearances of adult male and female redstarts. The adult male American redstart is a striking set of energetic visuals formed from plumage of orange, black and white. Adult females are similar to the male, with gray replacing the black and yellow instead of orange. Once a person is aware of these differences, redstarts are among the most easily identified warblers. Again, it’s the young male redstarts that pose a challenge for observers. Young males look more like adult females, but have an overall color pattern of light orange, white and gray with some black feathers around the face.
Bald eagles take four to five years to acquire the adult plumage, which includes the white head and tail that makes this large raptor so distinctive. Until the young eagles attain the striking contrast of brown and white feathers, they pose an identification challenge for novice birders. Although they have the large size and heavy bills of an adult, the plumage of an immature eagle is a dark brown overlaid with messy white streaking. They will only gradually gain more of the characteristic white feathering as they mature.
Bird identification takes practice, but new birders shouldn’t get discouraged. Learn the fundamental differences in appearance between male and female birds, and keep aware that the offspring of some birds can look quite different from their parents. It’s not easy, but it’s rewarding to begin to learn how to differentiate some of our common and not-so-common feathered friends.