Summer is a an excellent time to be a bird watcher in California. Ducks, geese, and many other varieties of aquatic birds concerned California come breed, build nests and also raise broods. If you walk to your neighborhood pond right now, opportunities are great that friend will watch a mallard or Canada goose paddling along with a gaggle of its offspring in tow.

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But watch for too long and you could find yourself wondering “how execute these birds stay warm and dry in the water?”

It’s a concern that Jack Dumbacher, curator the ornithology and mammalogy at the California Academy of sciences in mountain Francisco has actually been asked plenty of times.

The an enig to waterproof waterfowl, it transforms out, lies in their feathers.


“Aquatic bird feathers are really various than those of other birds,” Dumbacher said.

All birds have feathers. Their size, shape, and also structure differ widely, however all feathers fit right into one of 2 categories: under or contour.

Contour feathers, which include flight and tail feathers, are the long, rigid feathers that offer birds your shape and color. As the outermost layer, edge feathers serve as a bird’s first line that defense against the elements.

Vaned feathers aid birds fly, administer the contour to your bodies, and also keep water out. Down feathers are fuzzier and also hold a great of warm air alongside the bird"s skin below the vaned feathers. Part vaned feathers have some down feathers at their base. (Josh Cassidy/

Down feathers, by contrast, are the soft, fluffy feathers the sit closest come the bird’s skin. These keep birds warmth by trapping a great of air alongside their skin and are provided to do comforters, pillows, jackets, and also other products.

Every feather has a main hollow shaft, well-known as the rachis, and a flat area known as the vane. The vane is consisted of of thousands of branches known as barbs. Branching from this barbs are structures recognized as barbules, few of which room tapered v tiny hooks recognized as barbibcles.

Barbs extend out native the main rachis top top this vaned duck feather. (Josh Cassidy/

Unlike down feathers, edge feathers space loaded with barbicels the interlock the neighboring barbs together choose Velcro to type a wind and water-resistant barrier.

Some barbules have actually hooked barbicels at their tips permitting them to hook top top the barbules that the neighboring barbs. (Christopher Gilpin/Purdue University)

The strain of flight and also locomotion deserve to sometimes force barbules the end of alignment. Once this happens, the vane of the feather splits, permitting air and water to happen through. To protect against this indigenous happening, birds have tendency to your feathers regularly, in a process known as preening.

Birds preen through brushing their feathers with their bill. This process allows birds to keep their feather clean, smooth, and totally free of parasites.

A residential duck preens its feathers to reconnect the barbs and also spread wax on the surfaces. (Josh Cassidy/

Having well-groomed feather grants every birds some degree of water resistance, but aquatic birds take it to another level.

According to a 2016 study by scientists at the college of Debrecen in Hungary, aquatic birds prefer ducks and geese no only have feathers with denser, more tightly knit microstructures 보다 their terrestrial counterparts, yet they also have much more of them.

“In aquatic species, the density of the feathers is much, much higher than in terrestrial varieties of comparable body size,” claimed Orsolya Vincze, a research fellow at the Hungarian Academy of scientific researches who helped conduct the study. “The barbule density is likewise much higher.”

Having super-dense plumage makes aquatic bird far an ext water-resistant than their terrestrial cousins, however it doesn’t make them waterproof.

To achieve that, aquatic bird coat their feathers through an oily substance recognized as preen oil, i m sorry is secreted from a gland on your rumps, above their tail feathers. This gland, recognized as the uropygial or preen gland, is existing in virtually all birds, however its shape and size varies among species.

According to Dumbacher, aquatic birds tend to have actually much larger and much more developed preen glands 보다 terrestrial birds, i m sorry isn’t surprising since “they have to apply oil more regularly,” that said.

Most birds have actually a preen gland on your rump right over their tail feathers. It’s usually extended in stubby feathers the soak increase the greasy wax the the gland produces. (Josh Cassidy/

When preening, birds obstacle their beaks versus their preen gland to collect oil and also then rub it over your feathers. The oil from their preen gland coats the interlocking barbules of their feathers, calculation them waterproof.

It’s tough work. Some types will spend up to 25% of your waking hrs preening.

However, preening isn’t just around waterproofing. Preening likewise rids birds of parasites and also moisturizes their feathers therefore they deserve to stay flexible, strong, and also ready for flight.

Although the thick microstructure of their feathers and also applying copious quantities of preen oil each assist insulate aquatic bird from the elements, “it"s yes, really the mix of the two,” that permits them to continue to be warm and dry even in the chilliest of ponds, said Dumbacher.

If you desire to check out the wonder that waterproof feather in person, Dumbacher proposal heading down to your local pond to watch part ducks.

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“It"s fun to see just how water simply flips off the back of a duck,” Dumbacher said.