Date: 11/11/26 2:13 pm From: Clayton Will <willcfish...> Subject: [ia-bird] Not a sighting. Grebe flotation methods.
I noticed on eBird the Western Grebe near the Saylorville dam. I showed a
close up picture I had taken at the Ames borrow pit in 2019 to my wife Pam
and she commented the body was quite small in relation to the neck and
head. I told her they could sink out of site. Pam asked how they did that
so I asked Siri and learned a few amazing things. Especially the trapping
air in the feathers against the body and internal air sacs.
Credit, Tik Tok, National Audobon Society
Clayton Will
Madrid
Grebes have remarkable control over their buoyancy compared to most other
waterbirds, allowing them to float high like a cork or sink low like a
submarine depending on their needs. [1
<https://www.tiktok.com/@birdoftheweek/video/7113556702678601003?lang=en>, 2
<https://www.audubon.org/news/pied-billed-grebes-sink-submarines>]
1. Adjusting Feather and Air-Sac Buoyancy
When resting, preening, or swimming casually on the surface, a Western
grebe floats noticeably higher in the water by changing its body volume: [1
<https://www.audubon.org/news/pied-billed-grebes-sink-submarines>, 2
<https://www.tiktok.com/@birdoftheweek/video/7113556702678601003?lang=en>]
-
- *Trapping air in plumage.* Grebes have dense, waterproof feathers. By
fluffing their feathers slightly, they trap a thick layer of
insulating air
close to their skin, which increases their overall buoyancy and
lifts their
body higher on the surface. [1
<https://www.audubon.org/news/pied-billed-grebes-sink-submarines>]
- *Inflating internal air sacs.* Like other birds, grebes have internal
air sacs connected to their lungs. Expanding these sacs makes
the bird more
buoyant, while compressing them expels air and lets the bird ride low—or
sink straight down—when hiding from predators.
