What molting is

Feathers are made of keratin, the same material as your hair and fingernails. Like a fingernail, a feather can't repair itself once it's worn, frayed or broken. A year of flying, preening, sun and weather wears feathers down, and the only way to fix them is to grow new ones.

That's molting: pushing out old feathers and growing new ones in their place. It's not an injury or an illness. It's upkeep, the way you'd replace worn-out shoes.

Why now?

For most North American songbirds, the main molt happens after breeding season, roughly from July through September. The timing makes sense: nesting is done, the young birds are on their own, and late summer has plenty of insects, seeds and fruit to fuel new feathers. Growing new feathers takes a lot of energy, so birds do it when food is easy to find and they don't have chicks to feed.

If you're noticing scruffy birds in early October, you're seeing the tail end. Most birds have finished or are nearly finished molting, but late molters, birds that nested late and this year's young still look a bit patchy.

Young birds are part of the reason too. Many of this year's young are replacing their fluffy first feathers with their adult plumage. A young cardinal with patchy feathers and a dark beak isn't sick. It's growing up.

Why they don't lose all their feathers at once

Most songbirds molt gradually. They replace their flight feathers a few at a time, often in matching pairs on both wings, so they can keep flying the whole time. A bird that lost all its wing feathers at once couldn't escape a hawk or reach food.

Some waterbirds do things differently. Geese and ducks can shed many wing feathers at once and spend a few weeks unable to fly, staying safe on open water. Songbirds can't do that, so they molt slowly. That's why they look a little ragged for weeks instead of totally bare for a few days.

Yes, bald cardinals are (usually) normal

The most alarming sight at a fall feeder is a cardinal or Blue Jay with a completely bald, dark-skinned head. It looks awful, but it's usually not a problem.

Instead of replacing head feathers a few at a time, some cardinals and Blue Jays lose them all at once. Audubon calls it "perfectly natural (and necessary!)." The feathers grow back in a few weeks, and the bird looks normal again.

Researchers don't fully understand why some individuals molt this way. In some cases, feather mites or lice may be involved. Either way, a bald head on a bird that's otherwise alert, eating and flying normally usually isn't a concern.

Other fall "makeovers" you might notice

• American Goldfinches molt twice a year. In fall, bright yellow males turn a dull olive-brown and can look almost like a different species. They'll turn yellow again next spring.
• European Starlings grow new feathers with bright white tips, making them look covered in stars. Over the winter, the tips wear off and reveal their glossy spring feathers.
• Chickadees, titmice and wrens may look a bit rough while new feathers grow in, then look sharp and fluffy by late fall, ready for winter.

When to worry

A scruffy bird that's alert and active is almost always just molting. These signs point to something else:

• Lethargy. The bird sits still for a long time, stays fluffed up even in mild weather or lets you get unusually close.
• Eye problems. Red, swollen or crusty eyes, especially in House Finches, can be a sign of conjunctivitis.
• Growths or lesions on the face, legs or feet, which can indicate avian pox.
• Trouble flying or balancing, or staying on the feeder instead of flying away when startled.
• Visible injuries like blood, a drooping wing or a limp.

If you see any of these, take your feeders down, clean them thoroughly and wait a week or two before putting them back up. That keeps birds from gathering and spreading illness. If the bird is clearly injured or unable to fly, contact a local licensed wildlife rehabilitator. Don't try to care for it yourself.

Can your feeder help?

Molting birds happily eat high-fat and high-protein foods if they're available. Suet, mealworms, unsalted peanuts and black-oil sunflower seeds are all good choices this time of year.

But you don't need to change your feeding routine for molting birds. Wild birds get most of their food from nature, and a feeder only adds to that. If you search for "how to help molting birds," you'll find lots of advice about high-protein feed and protein percentages. Most of that is written for backyard chickens, whose owners control everything they eat. It doesn't apply to wild birds at a feeder.

Keep your usual feeder clean and stocked, add some suet as the weather cools, and let the birds do the rest.

Caught a scruffy bird on camera?

Birdbuddy gives you a close-up look at molt that's hard to get through binoculars. You can see a cardinal's head feathers growing back or a goldfinch changing color from week to week. Snapshots of the same scruffy regular can show the whole change from ragged to sleek over a few weeks.

Has a bald cardinal or a patchy Blue Jay given you a scare? Share your scruffiest visitors with the Birdbuddy community. Chances are someone else has had the same worry, and seeing it happen to other birds is reassuring.

The takeaway

Scruffy fall birds are almost always molting birds. Feathers can't repair themselves, so birds replace them after breeding season, slowly enough to keep flying. Bald cardinals and Blue Jays look alarming but are usually normal, and their feathers grow back in a few weeks. Watch for signs of real illness, like lethargy, eye problems or trouble flying. Otherwise, keep the feeder clean and enjoy the change.