You are watching: How can you tell how old a bird is
From the Summer 2017 issue of Living Bird magazine. Subscribe now.
Late summer is the time as soon as ragged, disheveled-looking birds start getting here at feeders. Gone is the sleek, clean look of spring. Part birds may also be missing feathers, as if they’ve come out the other finish of a bar fight.
These birds aren’t sick—they’re molting. Feathers are the specifying characteristic because that birds, and critically important for whatever from attracting mates, to keeping warm, to escaping predators. Yet they don’t critical forever, and most feather wear considerably over the course of a year. Reproduction season can be particularly rough, because of the frenetic activity and boosted abrasion from dozens of access time to well-hidden colonies in thick brush or cavities.
By so late summer feather are often at their worst, but fortunately food resources—insects and seeds—are abundant. So there is lot of of energy about for birds to put right into growing brand-new feathers. After ~ chicks have actually fledged and also before it’s time to leaving for migration, many adult birds take it the possibility to change those worn feathers. The chicks, top top the various other hand, space fresh out of the nest, so your molt schedule is contempt different.
Knowing a bit around what birds look like throughout the molt can be very useful information. In birding circles, molt has a reputation as an progressed skill. Yet if you eight yourself with simply a couple of straightforward ideas, they can reveal fascinating secrets about the bird you see.
Take a towhee, because that instance—Eastern or Spotted, depending upon which side of the continent girlfriend live on. A young towhee simply out that the swarm looks nearly nothing favor the dapper black-and-white adult males. Juveniles room brown and also streaky, showing the towhee’s sparrow heritage, the better to stay covert from threats while the young birds find out the ropes.
By loss these bird will have replaced those streaky human body feathers through the an ext traditional towhee pattern: shiny black on the head and earlier (brown in females), through chestnut flanks and also a white belly. But young birds molt only the body feathers, no the flight feathers in the wings and also tail, due to the fact that flight feathers need to be sturdy and also so take an ext energy to replace. First-year towhees won’t replace their brownish flight feathers until the next fall.
So if you ever before see a towhee hopping around your feeder with two-toned wings—nice black or wealthy brown scapulars and also wing coverts; dingy brown primaries, secondaries, and tail—you deserve to be certain that bird is a youngster that just hatched that previous summer.
American Goldfinches additionally show a difference between adult and also young birds due to molting. Because that example, male American Goldfinches all look shiny yellow in summer, but if you check out one through faded brown-black primaries, you know it’s a bird that just hatched the previous year. That looks a little like a human being wearing a new suit and worn-out shoes. And also once you can spot this sample in towhees and goldfinches, you can look for it in various other species, too.
Molt Limits: mental the Gap
In its second year, a young bird will finally replace its very first flight feathers. It is a great time to inspect out its wings. Look for a sample of worn old and also pristine brand-new feathers situated right beside each other. This is called the “molt limit,” therefore named because it mirrors how far the bird has progressed in molting. It have the right to be visible in adult birds, yet is simplest to see in the 2nd year.
Larger birds have actually larger feathers, which make them an excellent subjects for looking in ~ molt limits. While smaller birds to express in their molt in between the end of breeding and the beginning of migration, bigger birds don’t have that luxury. Feathers have the right to only thrive so fast, so larger birds often show evidence that molt for an ext of the year.
This condition enables birders to easily distinguish young bird from enlarge ones. Take the Turkey Vulture, which have the right to live because that 16 year or more. Juveniles and also adults look nearly identical, yet adults almost always show evident signs of molt in the warmer months. That takes a Turkey Vulture over one year to grow its foot-long trip feathers, one through one. When adult Turkey Vultures are molting, their older trip feathers are tattered and also abraded, and also there are noticeable gaps in the wing where new feathers room growing, not unlike the toothy laugh of a very first grader. On the various other hand, young Turkey Vultures recently out of the swarm will present a pristine profile v brand brand-new feathers all in great condition and also giving an even outline to the wing. The a difference that is noticeable even once birds are soaring at good distances.
And it works for most large birds, not just Turkey Vultures: try it out v your neighborhood Red-tailed Hawks, pelicans, and also cormorants. In fact, in the early 1980s this technique was critical in determining exactly how countless California Condors remained in the wild.
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These two patterns are just the start of what molt have the right to reveal about a bird. Some scientists have actually used molt fads to recognize whether a bird is a long- or short-distance migrant, or also as hints to when and also where a bird breeds. So take it a 2nd look in ~ those worn feathers. Yes sir a many to be learned also when birds room not at your best.
Nate Swick is society media manager because that the American Birding Association and also hosts the ABA’s American Birding podcast. He lives in Greensboro, phibìc Carolina.