|An immature spotted towhee shows streaked juvenile plumage. Photo by J. J. Meyer|
So you think you’ve sighted a rare bird. The color pattern is so unusual.
You consult multiple field guides before discovering that the sighting is actually a common bird, though an immature one that hasn’t yet developed its adult feathers.
Generally, juvenile plumage is drab and streaked to provide camouflage while the young birds are particularly vulnerable to predators. And it makes bird identification tricky this time of year.
Spotted towhees are a good example. As adults, these striking birds have jet-black heads and throats, prominent white spots on wings and backs, burnt orange flanks, bright white bellies and red eyes. Immature birds of this species are much less colorful with buffy brown heads and brown to black streaks across the breast. This juvenile plumage lasts only for a few weeks, though it takes nearly a year for these birds to develop its red eyes. Their eyes are brown for the birds’ first fall and winter, turning red by the following spring.
Immature Western bluebirds have a similar pattern: they show very little blue and have pronounced dark streaking across the chest and wings. Once a bird has molted out of this plumage it is no longer considered a juvenile.
While many songbirds lose their juvenile plumage in just a few weeks after leaving the nest, larger birds such as hawks can take much longer. Bald eagles don’t develop their distinctive white heads and tails until they are 4 to 5 years old.
Avid birder and professional photographer Anthony Gliozzo has taken many photos of common Orange County birds showing juvenile plumage for his website at ocbirds.com.
He says there are many factors to consider, such as behavior and vocalization, that can determine the bird species and whether the bird is a juvenile. “Don’t just rely on color for bird identification.”
If the bird is following a parent, or demonstrating begging behaviors, such as wing flapping with an open mouth, it’s obvious that it’s immature.
“Listen for begging calls or sounds that are incomplete or different than the adults,” he says.
And there are also oddities to look for in different species such as a brightly colored gape, or base of the bill. The corners of the mouth can be yellow, pink or orange, almost giving an appearance of lips. It’s commonly seen in wrens and black phoebes and suggests that a bird is immature.
Sometimes the behavior of young birds can appear uncoordinated, especially when they are learning to fly. Watching young mallards attempt to copy their parents feeding under water can be quite comical.
The breeding season is not yet over for many species. Many songbirds have two to three broods, or hatchings, so some are still raising their young. Mourning doves have a particularly prolonged season. These birds can have up to six broods per year. So it’s not unusual to see immature birds in August and September.